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Productivity 
of World 
Ecosystems 




National Academy of Sciences 



NAS-NAE 




I 



Productivity 

of World 
Ecosystems 



Fnnti'tlin^s of a Svmfynium 

Presented August 31 -September 1. 1972, 

at the V General AsKmbly of the 

^leciil Committee for the Inteimtioml BlolQgicel PMgnm 

Seattle. Waihinstoo 



Sympomm spomored by 

U.S. National Committee for the Intenntfaml Biological Pragram 

Division of Biological Sciencei 
Assembly uf Life Sciences 
National Reaearch Coundl 



NATIONAL ACADEMY OF SCIENCES 

WASHINGTON. D.C. 1975 

APR 1 81975 
LIBRARY 

Copyrighted material 



NOTICK; The symposium reported herein was undertaken under the aegis of the National Research Council with the cxprcu approval of its 
Governing Board. Such apptovil indicated tliat dw Bond considered the problem to be of national Mgnificance, that its elucidation required 
Kiantifle or tcdinkal ooim|M|tnw,«nd tint imdumbi of NRC were puiiciilaily luitable to the coaduct of Uie jwojact. The imtitutionat 
napondbaitiM of A* imc wan tfMm diadiiiiad iB dw fellBwiiig 

TJm partlripat* in the qrmpoiiiim weie ttlected for iheif individual sdioUrly competence and judgment with due consideration for the 
iMliaoaand breadth ofdiKlpBnes. Refpontibility for all aspects of this report rests with them and with the organizing committee, to «riiom 

dnomapprt^ i.-ilLm n expt^wii 

Althou^ proceedings of symposia are not submitted for approval lo the Academy membership or to the Council, each is reviewed according 
to procedures established and monitored by the Academy's Report Review Committee. Such reviews are intended to determit>e, inter alu, 
whether the m^oc queitions and relevant points of tri«w have been addretaed and whether the reported Hndinis and conduttom arose from the 
avaHabie data and informatloa. DiitrflHitk>a it approved, by the Fteildent, Miiy aflar ntit^tory com{detton of thh review prooeu. 



Tkit «ympoiliiiii wu mpported fey die Natfonal Sdaaee FoMndidm. 

Main entry uttder title: 

l>roductivity ul v-t rld ecosystem*. 
Includes bibliograplues. 

I. Btolofpcal productivity -Congrenes. i. International Council of Sdentinc Unions. Spedal Committee for the International Biologkal 
fmnuHM. IL U^. National Committee for the laleroatioaal Biological Program. (DNLM: 1. Eooiogy-CoDgreiiea. 2. Enviroaiaent- 
ODiWMNi.QH541 F963S 1972] 

l8BN<M094n317-9 

AvaSaNe from 

Printing and PubUifajiig OfOca, National Academy of Sdenoat 
2101 Onosdladon Avorn, N.W., Wadyi«lm, OjC. 2M1S 



Mntad in dw Unitad Stalw of America 



Copyrighted material 



PREFACE 



TWl symposium reflects one of the central objectives of the International Bio- 
logical Program: the worldwide study of organic production on the land, in 
fresh waters, and in the seas, and the potentialities and uses of new as well as 
of existing natural fesources. It examines the productivity of oceans, freah 
water, gFBidand, desert, tempente forests, and tundra. It seeks to respond to 
these questions: What are the ranges of productivity in each ecosystem'' What 
are the factors that provide the main controls in each? What are the potentials 
for utilizing and increasing productivity in man^ interest? 

^oe the symposiuni, many of the contributors h«n had occasion to update 
their material and to provide formal pepers that entaige upon the initial presen- 
tations. 

DAVID E. REICHLB 

JERRY F. FRANKLIN 
DAVID W. 600DALL 



IN 



Copyrighted material 



EXECUTIVE COMMITTEE OF THE 

U.S. NATIONAL COMMITTEE FOR THE IBP 



John F. Reed, Chairman 
Stanley I. Auerbach 
hiul T.Baker 
Stanley A. Gun 
Everett S. Lee 
Terence A. Rogers 
George F. Sprague 
Kenneth V. Thimann 
FtedeiicH. Wagner 

OROANIZING COMMITTEE FOR THE 
V GENERAL ASSEMBLY, IBP 

W. Frank Blair, Oilman 

James S. Bethel 
Everett S. Lee 
Jerry S. Olson 

SUBCOMMITTEE ON PRODUCTIVITY SYMPOSIUM 

Jeny F. Franklin, CAafrman 

David W. Goodall 
David £. Reichie 



CONTENTS 



Productivity of Tundra Ecosystems 


I 


■ F. E. Wielgolaski 




Productivity of the World's Main Ecosystems 


13 


^ L E Rodin. N. I Bazilevich. and N. N. Rozov 




Productivity of Marine Ecosystems 


11 


M. J. Dunbar 




An Analysis of Factors Governing Productivity in Lakes and Reservoirs 


32 


^' JW. Brylinsky and K. II. Mann 




Productivity of Forest Ecosystems 


33 


Jerry S. Olson 




Productivity of Grassland Ecosystems 


44 


R. T. Coupland 




The Importance of Different Energy Sources in Freshwater Ecosystems 


50 


K W Cummins 




Terrestrial Decomposition 


55 


Dennis Parkinson 




Measurement of Primary Productivity by Gas Exchange Studies in the IBP 


60 


Richard B. Walker 




The Role of Herbivore Consumers in Various Ecosystems 


64 


K. Petrtisewicz and W. L. Grodzinski 



«1 



Secondary Productivity in the Sea 


71 


. D.J. Crisp 




Decomposition of AUochthonous Organic Matter and Secondary Production 


in Stream Ecosystems 


90 


N. K. KausMk 




Nutrient Cycling in Freshwater Ecosystems 


96 


, D.W. Schindler, D. R. S. Lean, and E. J. Fee 




Productivity and Mineral Cycling in Tropical Forests 


106 


. Frank B. Golley 




Analysis of Carbon Flow and Productivity in a Temperate Deciduous Forest 


Ecosystem 


116 


W. F. Harris. P. Solllns. N. T. Edwards. B. E. Dinger, and H. H. Shugart 


Plant Nutrients as Limiting Factors in Ecosystem Dynamics 


123 


C. O Tamm 




Mineral Cycling in Terrestrial Ecosystems 


133 


P. Duvigneaud and S. Denaeyer-De Smet 




Hydrologic Transport Models 


ISS 


D. D. Huff 




Contributors 


165 



PRODUCTIVITY OF 
TUNDRA ECOSYSTEMS 



F. E. WIELGOLASKI 



ABSTRACT 

A review of p/odULtivity j;udii;>; m tundra taoiyvienis sluwi iftat 
primary production is the best knijwn L-tu'^vstL-rr. pjramL-tcr. Rcults 
from bo(h repeated harvestinits and physiological measuiemertts are 
(hren. Yearly production ranges from lea than 10 g/m' /yr to 400 
IB 300 i/m'/rr abemtfomuA miculu iiluitt. On a daily bMli 
primvy prodnclfvity tn tttwln iRiy b« comiilanbto: «i1bm of S to 6 
j[/m' 'day arc found when above- and belowground parts and 
vascubt plant) and cryptograms are combined. Some estimates of 
the tundra microflora arc ahn civi-n 

The ratio of abovegiuund : belowground parts of vascular plants 
decreases with temperature, oUgotrophy, and water content of aol, 
Le., with ilryr fating dccompoattion rate. Lowest ratios, down to 
•boat I : M, am fbuad on wdfo-doaiiiatad wet araas «Mi IMtad 
amoium of ihiuba in aictic aad alpliia tundra . 

TIm influence of the nnan mammal population cycles on 
prinuny IWOduction is mentioned as well as the interaction between 
grazing by large mammals, especially reindeer, and plant growth. 
The direct influence of invertelnatet on plant biomau b small, but 
iamtabiatct in ibc vmeuiion layer an Impoitant for bird*, and 
fawmtoilai In tte iBl tofhuaee (he decoapoillloB lats. In»ait»> 
bnia Uanun is difTtcuit to meanue, but aom otnda aeliRMlet an 
flvea. Nematoda, Enchytraeidae. ketH end Colembola are found 
to be the most important invertebrate groups in the tundra. 
Vertebrate biomais is summarized for various tundra areas. Verte- 
brates gienetally comtiluis u smaller energy flow component of the 
tundia ecosystem than the plant-soil organic-decompoiet cycle, 
aiUMMiili diay ate tiiU important. Some pnHminaiy nhm tot 
dacoMpoMon ntaa in tnndia aia glwn. For aona abovniannd 
phnt nHtmidi weiiht lonee may be 25 to 9S percent daring Hie 
first year, usually it is less. Although energy and carbon flow 
throu^ tundra ecosystems is the primary aim of the tundra studies, 
work on nuirir-nt cycles fg allo in pioiieM^ paiticidaity on p to^ 
lenu of niuogen supply. 



INTROOUCnON 

1>indi« it often defined as aieas wifli peimefroit bi the 

soil. This situation may occur in both polar and mountain 
regioiu. Within IBP, studies are carried out in both Arctic 
and subarctic tundra ecosystems in die U JJS.R., Cuada, 
U.S.A., Finland and Greenland, in Antarctic ecosystems 
at South Georgia and Macquarie Island and in mountain 
areas with or without permafrost in Sweden, Norway and 
Austria, as well as in tundra-fike blanket bogs in Great Bdt- 
ain and Ireland. The studies are coordinated by the Inter- 
national Tundra Biome Steering Committee. 

Tundra areas may be divided into difTerent zones. The 
biology of .Arctic, Antarctic and alpine tundra will vary, 
and the moorland areas included in the IBP tundra studies 
are in many ways different from the polar areas, e.g., lack- 
ing the permafrost. There also may be a zonation of the 
tundra for the continents of Eurasia and North America, 
fiom north (Aietk areai) to aoudi (sidMietle anas) In id*- 
tjon to solar radiation as well as from west to east because 
of changes in continentality of climate (mainly changes in 
temperature and pneipltatioD). In the VSSIL several at> 
tempts have been made to differentiate regions within the 
tundra (see the review by Alexandrova, 1970). Climate com- 
bined with vegetation studies has been die main criterion 

for tundra classification in the U.S.S.R. Similar methods 
have been used in Canada (e.g., see Beschel, 1970). The nu- 
trient content of the soil could also be used for eatogoitahig 

various eutrophic and oligotrophic tundra types. A rou^ 
classification of the tundra sites witliin IBP is based on vege- 



Copyrighted material 



2 



F. E.WIELGOLASKI 



tation studies (Wielgolaski, 1972a). More advanced techniques 
oouid abobeund, e^^ piliiGlphcaiiipoimt analyrfi, which 

has been used for IBP sites (e.g., Moore, personal communi- 
cation, 1969) and foi some areas in Canada (Beschel, 1970). 

Moat tundra to biologically fragOe. Tufldia araai iMiaDy 
share a severe environmental situation with low temperatures 
and a short growing season. Therefore, annual biological 
productivity ii luudly low as to tlie munber of special bodi 
of plants and animals Bliss (1970) states it is generally 
accepted that a small biomass and low annual production 
favor eeologicai and taxonomlc liinplteity and hence ayitem 
instability. Daily productivity may be as high in tundra areas 
as in other parts of the world, however. There may be great 
dUfinenoes in productivity from year to year caused both by 
variations in environment, small mammal populations, and 
the carnivores preying upon them. The consumer component 
of tundra ecosystenu is especially important for the nutrient 
cycling and energy flow through the system in years with 
liigb snull mammal populations. Even then, however, the 
decompowr pathway is the major route for bnakdown of 
plant materials as in most other terrestrial ecosystems. Still, 
the systems wiU not function without confumers-both in 
the soil and aboveground. 

Before IBP, studies of tundra ecosystems were carried 
out mainly in the U.S.S.R. and USA. A survey of Russian 
tundra literature is found in Alexandrova (1970); Firsova 
efdl, (1969) and TiidioiiUTov (1971) are additional exam* 
plaiy papers on tundra productivity in U.S.S.R. Literature 
concerning extensive studies of lemming cycles at Point Bar- 
row, Alaska, is cited by Bliss (1970). Rodin and Bailavich 
(1967) and Bliss (1962, 1966) have summarized Arctic re- 
search on primary production. A review of IBP timdra 
■tudiataiid aosne praUmhiuy lesulu are ghmi hi Heal (1971) 
Mid in Wielgolaski and Ronwall (1972), and results on soil 
oiganiams and decomposition &om IBP tundra studies are 
givan hi Ikldh« et A (1974). It can be ajqiaeted that widitai 
a few years much more infonnation will be available on pro- 
ductivity of tundra ecosystems [e.g.. Moore, in preparation; 
Walaolailcl»hi|mtt(a)]. 

PRIMARY PRODUCTION 

Most work on tundra ecosystems concerns biomass and 
production of plants, esjpecially the aboveground biomass 
of higher plants(Blb>. 1962. 1966, 1970: and Aodiaev. 
1966. Khodachek, ]%9. Alexandrova. 1970;Wiel|aladd, 
1972; Bliss and WielgoUski, 1973). 



The biomaaa of higher plants may be very small in zonal 
flMrifled u polar desert by Alexandrova (1970), e.g., 6 tJm} 
in moia-licben pdyions at Franz Josef Land (Table 1 ). Low 
Moman valuai ai* alio found in other areas with only patchy 



vegetation, while higher values, 15-50 g/m' , may be found 
in 5U£r fufbacta snow beds in Norway at 1 300 m above 
sea level and 60°N latitude [Wielgolaski, 1972, in press (a)) . 

Even in the polar deserts the amount of cryptogams may 
be radier hi^ Alexandrova (1970) reports 123 g/m' , wUle 
Andrecv (1966) reports only 9g/m' in polar semideserts, a 
northern variant of arctic tundra with more than SO percent 
bare loil. In Ihe Norwegian mow bed mentioned above fhe 

crv'ptogam biomass was ~40 g/m' . The highest amounts of 
living aboveground biomass of cryptogams reaches 1,345 
g/m* (Alexandrova, 1970) hi Arab tundra, 800 g/m' for a 

polygonal bog (Khodachek, 1969; Shamurin et al, 1972), 
and about 400 g/m' for a flat palsa bog (Pospelova, 1972). 

When both above* and belowgnxmd Uoman of phanero* 
gams are sunmied with cryptogams (Alexandrova, 1970) a 
total biomass of - 1 50 g/m' occurs in the polar desert and 
~200 g/m* in alpine snow bedi hi Norway. Thto luggesis 
that even in closed vegetation in alpine areas, at a low lati- 
tude the total amount of biomass may be nearly as low as 
in polar deaarti at a hl^ latitude. 

Vassiljevskaja and Grishina (1972) found that organic 
matter reserves in both the total plant biomass (living and 
deaiO and sofl organic matter increased from duvial to 
aocumulativa landscapes in Western Taimyr, e.g., fran 
spotted Oryaj-moss tundra to a marshy brush-sedge-moss 
tundra (Table 2). The biomass ratio between the vegetation 
typaa was 2.77 and in soil organic matter, 2.12. At the Nor> 
wegian IBP tundra sites at Hardangervidda the total carbon 
content of sod organic matter in a dry meadow with Dryas 
to comparable to tiiat found hi the Russian Drym tondn. 
Smilar carbon values to the marshy tundra in Taimyr are 
found in SoQ organic matter in a Norwegian wet peaty sedge 
meadow (Vaum, peraonal coramunicalioa, 1972). The ratio 

of total biomass between the two types in Norway (3.33) 
was somewhat higher than in U.S.S.R., while the ratio in 
■oH organic matter wai dii^itly lower (2J06). The latioi b» 
twcen carbon in soil organic matter and biomass were high- 
est at the driest sites in both U.S.S.R. and Norway. The 
latloa were hiilier in Nocway than at afanilar vafBtatkm aitaa 
in U.S.S.R., e g., 19 2 at the dry meadow in Norway and 
12.2 at the Dryas tundra in the U.S.SJL which may reflect 
tafluenoei of lha oceanic dfanate. 

The maximum aboveground Vvnn^ biomass of vascular 
plants diiTers very much from site to site but could be 
grouped hi 5 to 6 groups CnMa O.lliareto.of coune,a 
gradient from the most Arctic sites with low temperatures 
to sites with more favorable CMiditions for growth. For 
example, at Ifa id an g etvidda. Norway, the average yaaily 
temperature is sligtuly below 0°C, while at Macquarie Island 
it to AS'C (Jenkin and Aihton, 1970); both of these sites 
have much hl^itr tempentom than Tihnyr at about -IS*C 
(Matveyeva, 1972). At Moor House, a moorland site in 
United Kingdom at about M'SO'N, the maximum above- 
ground vaacular ttvtaig bhanaN wai about 8S0 g/m' (Forrest, 



Copyrigliico r:ia:.crial 



mooucn viTV of tundna toosvsniM 



3 



TABLE 1 Toul Liv« Atoovaground VbmuIw Ptant Bionun (9/ni dry Meight) at the Time of Maximum 





Ana 


SMaTypai 


g/ni 


Referenoei 




FnuB JoaefLand 


falai(teiert 


6 


Alexandrova, 1970 


Nocwiy 


HudaiiiiUvUda 


AlplM iiww bad 


IS-SO 


ee n ■ e a i ■ f a * - ^ _ ^ ^ ^ 

wMiMada, 197Zt M inau (ai 


<^iiad8 


DevoBldaiid 


Ptateaa 


20 


Bdn, 1972 


Norwiy 


HaidangervkMa 


Lichen heath 


30-60 


tif'^i 1 a-' • i\ ^ ^ * V 

Wielgouiiki, 1972, in pren (a) 


UAUL 


Norlheastera Eurofie 


Polar «:mnic«rt 


40 


Andreev, 1966 




Devon Idand 


Sedge meadow 


60-90 


Muc. 1973 


UJJJL 




Aictlc fMidia 


71 


AlenadRm. 1970 




Devon Idand 


Railed beech ridge 


90-130 


Svoboda. 1973 


Monny 


HaidamanMda 


Ihyawtiiatnaadaw 


90-140 


WalioUdd, 1973. lo piea (b) 


(UAH* 


Trfaiyr 








f 1 C A 

U.S. A. 


roint BHIOw 


fUUA J 

wet iMBa BMaoow 




iiesxon, i7r^ 


Swedan 


AmilU} 


Bet 


1 ■ A 




II ■ a D 




spoiico cuirapiiwaipnii 


1 lA 


vnapwiiOi Vrn 






tundra 






I7iMt«IMl 


if MM 


Ctaetialaia a^ k^A^k 

aUDIipilli MBUI 


to* 


aaiiio aiiQ nanfliainpit irti 




WnlmTakiQrF 




laa 


riiMiriiiBi iwn 
nNpemai iTr* 




Talnyi 


MyionllMig 


190 


ahanarin «rae. 1972 




Sdalhaid 


HoM-AnilHiiiaHKoek 


Am 
















Clfiiinr 






(4oo rc , pernio n III 










/^'\mm kin 1 tr«n 1 

tuiLiinuniwiiiiunf i 7 'V 




WatianiTaiaQrt 


Flat pain bqg 


513 


FoapalovB, 1972 


UJUJL 




AlpfaanaadMV 


S2t 


C:kipiiikn,1972 


Autnlia 


Miniiiiili Minll 


ITwMlald 


«1S 


JaaUaaadAdrton. 1970 


Norway 


Hudanfervidd* 


WilJow thicket 


800 


Kelvik and KlrenUmpi, in 


U.S.S.R. 


Eastein Europe 


Shrub tundra 


817 


Alexandrova, 1970 


United Ki^ioa 


1 MoorHooie 


Blanket bog 


846 


Forrest, 1971 


Attstnlim 


Macquarie Iiland 


GrutUnd 


1.138 


Jenkin and Aihton, 1970 


Auitria 


Patseherkofel 


Loisclcurietum 


1.150 


Larcherrrail. 1973 



107!) At herbfield and grassland sites on Macquarie Island 
at a &uitUai latitude in the southern hemisphere (Jenkins and 
Adtton, 1970) even higher values were found, which nufCd 
up to above 1,100 g/m^ . Naturally, the bionnass is also con- 
siderable where the amount of woody plants is high, run- 
iiliigiipto817g^* iiitiliral»tuiMlniinth»6MtBiiriop«ai 
forcst-tundra region (Alexandrova, !970), and still highar 
in alpine regions in Austria (850 to 1 ,200 g/m' in IBP 
studiet (Laidwr et 1973)) . 

The biomass of belowground parts is sometimes hl^ even 
fal Arctic and high alpine areas. This is especially true of 
•ome of the dtM imwUptod In VSS JL (KhodiclMk, 1969; 
.Vlexandrova, 1970; Pospelova, 1972; Shamurin er a!.. 1972) 
and for some sedge meadows in Canada (Muc, 1973) and 
Nofwiy (W^lgolasld, 1972b). GeneiaUy tt leemi flut the 
amount of belowground relative to aboveground parts is 
cqiecially high in wet areas with relatively low amounts of 
dmiln eonpaiMl to herbs. 



TABLE 2 Total Carbon in Biomaas (Livinfl and Dead 
Aboin- and Batuwpowwl Compenarti) and In loi 
Organic Mrttarfgr Ac UJJJI.and Nonnv 1M« 

Sites 









Soil 

Oiganic 
MatlR 


Sott 

OigtaiD 

Matlai: 


Sites 






(gC/m') 


Ratio 




Spotted 


1,049 


12.784 


12.2 




brUbh-«d^o- 
mass tundca 


3,907 


27.096 


9.3 


Norway 


Dry meadow 
Ida (mUkDrjm) 
Vetpeatjr 


825 
2,750 


15,795 
32.506 


19.2 
11.0 



Copyrighted material 



4 



F.E.«mU0OLAIKl 



Ratios of Abovvground to B ri owgnoyad BioniMi (A/B) 

The ratios at peak above^round biomass are of the order 120 
and 1:10 lor live, and live and dead material at the wet 
sedge dominated meadow in Norway (Wielgolaski and 
Kjelvik, in pres<;) For some of the sedpe meadows at Devon 
Island, Canada, A/'B ratios of live material about 1:12 aie 
cdciiliied (Mue, 1973). Ib a polygond bog at Tainiyr, 
US S R CShamiirin era/., 1972), the ratio is l:17for total 
organic mattei (live and dead), and in spotted Do^cu- 
aedl8e4noiMy tundtas in the laniearea theTntloia t:t2 

(Pospclova, Shamiirin et a!.. !97:). These low 

ratios are of the same order as the lowest ones found by 
Dennis (1968) and by Alaxandrova (1958, 1970). Some- 
what higher ratios (about 1 : 10) are usually found if only 
living parts of above- and belowground vej^tation are con- 
dderad (Wielgoladd, 1972). Higher ratios are foand fai 

tundra areas with higher percentages uf shnihs. In a spotted 
Ayos-sedge-mossy tundra in the Aiy-Mas forest in Taimyr, 
(gnatenlco etal. (1972) reported an aboveground:below* 
ground ratio for total vi-gelation of about 1 : S3 (ranging 
from alraut 1 : 3.9 at the ridges to 1 : 6.2 in the depressions). 
Still this was a lowar ratio than for forest vegetation in the 
same area (ratios 1 :2 to 1 :3). Alexandrova (1970) reports 
a ratio of 1 :6.9 for total biomass or 1 :4.S for living bio- 
mass in a shrub tundra in an East European forest tundra 
region. Pospelova (1972) has found values for above- and 
belowground total biomass in shrubby vegetation types in 
Western Taimyr giving ratios from 1 :6 to 1 : 4, while Chep- 
tl|tEO(l972) at Kola found ratioa of about 1 :3. The same 
ratio was calculated from preliminary results from a bog in 
Northern Sweden. Dennis (1958) has reported the lughiest 
ratios aboveground : belowground to be about 1 : S and 
Alexandrova (1958) about 1 :4 which is of the same order 
as the other ratios mentioned. Frcm values reported by 
HeBtn (1972) for the wet sedge meadow at Point Baiiow, 
Alaska, a ratio of 1 ; 6 could be calculated for living parts. 

Still higher ratios of living biomass are found at IBP 
tnndia litai fai NofdMin Finland dombiatad by AnpemMi 
and Vaccinium species as well as at the alpine sites in Austria 
with similar vegetation {Vaccmium, Qdluna and Loiseteun). 
1lMiatioaatlh«aaiitesiani»fhMn l:2to r.O^.WMifai 
the same range are the ratios at the moorland sites in the 
United Kingdom and Ireland. These ratios are. however, low- 
w than ratios reported from giaarfand vegetation ta temper- 
ate r^ons. For instance, studies of grassland areas in New 
Zealand at even 1,000 m above sea level show an above- 
ground :bdo«gnnind ratio for Ihring bfomaM of about 1 : 
O.OS. Relatively hi^ ratios for herbaceous vegetation an 
also reported by Bray (1963). These data confinn the 
hypothesis that a typical tundra environmant is relathrely 
more severe for aboveground than for belowiround parts 
of the plants (Bliss, 1970). Even if the yearly growth of 
belowground compartments is normally slow, the mortality 



and decomposition of roots are also low. Consequently, the 
belowground biomass is great. Tlia decomposition rate is 
usually slowest at the lowest temperatures; however, oxygMl 
availability in the soil is also important. The belowground 
biomaat will, theiefois, normally be M^Mit In relation to 
aboveground in wet peaty soil with poor aeration. This is 
supported by data from Alexandrova 's (1970) studies, for 
example. Deoompoiition rates will alao be (omewkat Mi^r 
in nutrient-rich soils than in oligotrophic soils. That may i>e 
the reason for the relatively higli aboveground : belowground 
ratio (1 :4X)) found bi an alpine meadow on the Kola penin- 
sula (Chepurko, 1Q72) 

These hypotheses are confirmed in Norwegian IBP tundra 
studies (Wielgolaski, 1972b). The Mghast A/B ratioa of Ihdng 
biomass (undcistary 1 3 to 1 .4. total 1 :0.6) are found in a 
birch wood at a lower altitude and, therefore, with relatively 
higher temperatures. Above the tree line ntios of the aame 
order (! 4 to 1 7) are found in a poor, but relatively warm, 
lichen health with sandy , weU-aerated. and often dry tod 
deficient bi humus as fai a somewhat more hundd and ridi- 
er dry meadow at about the same altitude where decompo- 
sitioQ is relatively fast because of good nutrient conditions. 
In the Stdix hethaeea mow bed decomposition is relatlvety 
slow because of both the short period without snow and 
the nutrient deficient soil. Here, theiefoie. the ratio abov^ 
ground :beIowground is relathrely low hi spite of the Arab 
dominated vegetation (1 :S to 1 :9), but still noticeably 
higher than in the frequently saturated wet sedge meadows 
cited earlier. 

Production 

Pttanaiy pfoduetlon can be datenniMd by nepeated bar- 

vestings, preferably of both above- and belowgroimd bio- 
mass. Estimates of tlte production can also be developed 
from phytoqmfliesls-fMpiEatloR vahMBwhen trandocation 
within the plant is taken into account. Chlorophyll mea- 
surements and carbohydrate analyses are a third method 
used In primary production studies. Harvesting has been tlie 

major method used in tundra prodiirfion studies. 

Primary production is often described as tlie difference 
between biomass at the time of peak Hiring aboveground 

vascular plant biomass and the biomass of the same parts 
before the growth season begins. This gives only a very 
rou^ estimate of the plant production, however. WhOe 
the green parts of vascular plants have the greatest incre- 
ment in biomass in the early sununer, tlw root biomass most 
often decreases in spring beeauae of translocation of food 
reserves for new green growth. To a certain e,vtent the SSOM 
pattern exists in tundra areas for nongreen, living, above- 
ground parts during periods of high respintion in spring, b» 
fore photosynthesis of green parts is high enough to com- 
pensate for respiration. Usually, tundra root mass increases 
most in the autumn when the green parts decrease. Ijchens 



Copyrigliico r:ia:.chal 



roOOOCTIVITY OF TUNDRA ECOSYSTEMS 



5 



and, to some extent, bryophy tes al«o continue growth until 
nhthrdy late tntumn in tuodnareaa. 

Decreases in biomais between two summer hap. csting$ 
may be found for all plant compartments. This can result 
fnMn hirmting erron, but mortality of plant paiti, d»> 
composition, and animal consumption may also be respon- 
sible. In the IBP tundra studies, for example, decreases in 
Ihring bkrnnK are aometfenei found for bdowground mate- 

rial between the time of maximum aboveground living 
material and the start of the growing season at some wet 
aedge m«adow Am. Thb Indicatai rimply that most Mowi> 
ground growth takes place in relatively late autumn after 
afaoveground biomass peaks. "Production" of green com- 
ponent! may be taken as Hie inereaae in green blomass, phii 
any increase in mass of standing dead aboveground and of 
litter. This aanimes that the increased weight of theae dead 
paili eomei moidy from the green nuterlal; if thb mortal* 
Uy had not occurred during the growth period, the green 
parts would have increased accordin^y. When dead parts of 
the plants have lower weight at later harvestings, decompo- 
dtion can be considered responsible. 

Annual primary productivity is normally low in tundra 
which IS frequently a consequence of a very short growing 
aaaio n l ei i than two months in extreme cases. In Taimyr 
the growing season lasts about 80 days, at Hardangervidda 
in Norway about 100 days, and at Moor House in the United 
Klngdam about 180 days. The M^wat yearfy dry matter 
production is found at tundra sites in the lowest latitudes, 
Le., the Austrian IBP sites in the northern hemisphere and 
at Macquarie Island in the southern hamlsiAere, as well as 
on moorlands in Ireland and the United Kingdom. At those 
sites the green vascular plant production ranged from 100 
to 400 g/m* . When bdowgroiuid production wu added, 
the total biomass of vascular plants at Moor House in- 
creased annually by the order of 600 to 700 g/m^ , with 
about half of die prodncthity be l oiig i o o nd (Forrest, 1971). 
Bryophyte production at Moor House was also considerable, 
i.e., up to 300 g/m' in Sphaputm (Clymo, 1970). Relatively 
high primary productivity was abo finmd at some ittesin 
the U.S.S.R., such as in relatively dry alpine meadows on 
the Kola Peninsula (Chepurko, 1972). as well as in Norway 
[Wielgolaski. in press (b)] . TTie total yearly productioa (vascu- 
lar plants) was about 500 g/m' , 225 g/m^ aboveground and 
275 g/m^ belowground. Even higher primary production 
have been calculated for wet eutrophk alpine meadows in 
Nonray (vascular pUnu about 650 g/m' ). Relativaly Ugh 
values were also found at a marshy brush-sedge-moss site 
in Western Taimyr (Pospelova, 1972); total yearly produc* 
tion was about 400 g/m' > but on^ 60 g/m' was above- 
ground. 

Many tundra sites have an aboveground vascular plant 
production of 40 to 100 g/m^ and a total vascular plant 
accretion of 100 to 200 g/m' . For example, such values 
were attained at many Russian tundra sites (Andreev, 1966; 



Chepurko, 1972), on sedge meadows at Devon Island in 
Guiada (Mue, 1973) and at aome Finnidi sites in the under* 
stoiy of sub-dpine woodlands (KaUio and KArenkmpi, 

1971) . 

Low aboveground vascular plant productkm (leu than 

,^0 B.';n' ) was found in snow beds in Norway (Wielgolaski, 
unpubl.). the northern arctic tundra of the U,S.S Jl. (Andreev, 
1966). some spotted tundras in the U5.S J(. (Chepurko. 
1972; Pospelova, 1972), and in beach ridges and a plateau 
at Devon Island (Svoboda, 1973). Including lichens and 
bryophytes. a Udien heaOi In Nbiway diowed a production 
of more than 1 50 g/m^ aboveground, however (Kjelvik and 
Kirenlampi, in press). Cryptogams also contributed signifi- 
cantly to primary production at otfier dtes, 30 to above 
200 g/m^ by mosses in meadows in Norway and at Devon 
Island, Canada, for example (Pakarinen and Vitt, 1973; 
Wielgolaski, in press (b)] . 

Primary production may vary considerably from year 
to year for several reasons including lemming cycles and 
climatic variations. Dennis (1968) found variations in 
aboveground dry matter production from 60 to 97 g/m' 
in 1964 and from 3 to 48 g/m' in 1965, when lemming 
populations were high. Several years are therefore necessary 
for productivity estinutes. Hie vduea eited eariier are 
mostly from only a few years of IBP-tundra studies; they are, 
however, mostly within the 50 to 200 g/m^ productivity 
tangs fiMuid in other tundra lnwesti|itfcMa(BtliB, 1970). 
The extremely low yearly production at tSalix artica- 
dominated barren site (3 g/m' ) on CorawaUis (Warren 
unison, 1957) lies baker the vahias reported hi fUs paper. 

The daily aboveground primary productivity may be 
lather high in tundra areas. Bliss (1970) having recorded 
up to 3 g/'m' /day. incoming radiation may be hi^ and the 
energy balance is often positive during the whole 24-hour 
period in polar areas during parts of the growing season, 
e.g., until August 60i hi Taimyr, U5.S J(. (Zaienak^ et aL , 

1972) . Ticszen (1972) found positive photosynthesis over 
24-houi periods at Point Banow, Alaska, on most days up 
to August 2nd. BHas (1972) reported that Dryas h photo* 
synthetically active within a few days of snow melt. Photo- 
synthetic values for Dryas were quite comparable to tem- 
perate zone grasses and tree leadlhigii On dear days moat 
Dryas production took place at ni|fit bacinae of hiifi tem- 
peratures during the day. 

Stin, dbethe utillation of solar energy by plants may 
be rather low In tundra areas, e.g., 0.7 percent on a spotted 
/)k7ii4no8B tundra and 1 .8 percent on a marshy tundra fat 
Wsitem Taimyr (Vassiljevskay a and Grishina, 1972). At flie 
latter site daily total primary production was 5 to 6 g/m' 
(Pospelova, 1972), but only about 1 g/m} was aboveground 
productivity. Daily production ranged to as low as 2 g/m' 
at other sites in the same area, i.e., in a spotted Drvos-moss 
tundra (0.25 g/m'/day in aboveground production) Based 
on maximum values for aboveground living biomass and 



F. i.1INCUI0UiaKI 



UonuM of limiar components at the beginning of (he 

vegetative period, an average tdtal daily prcniuction of 
about 2 g/m^ is found at the tundra dry meadow in Norway. 
Cooiidering 13m diffeient growth periods for tops and roots 
and for vascular plants and cryptogams, the daily total 
primary production of the same site (without compensation 
for oonsumption, but for decomposition) was about S g/m' ; 
about half was aboveground parts [Wielgolaski, in press (b)], 
ranging from about 25 to 6 g/m' in different yean. Even 
somewhat hi^^er values were calculated for wet, eutrophic 
dpine meadows in Norway. At Moor House daily above- 
ground production was about 1.6 g/m' (Forrest, 1971). 

Measurements of photosynthesis and respiration by 
tundra plants relevant to productivity estimates have been 
performed by Hadley and Bliss (1964), Scott and Billingl 
(1964) and Johnson and Kelley (1970), among others. 
Within the IBP'tondia group the same processes are being 
studied in several countries. Tieszen (1972) has provided 
preliminary data on wet sedge meadow at Point Barrow, 
Alaska. Net CO] incorporation by photosynthesis is esti- 
mated to be 9 to 12 g/m' /day. This converts to 6 to 8 g/m*/ 
day of dry matter which is ccwnparable to daily production 
eslculated by harvesting at tlie wet sedge meadow in Norway 
which usually has higher temperatures but shorter days 
[Wielgolaski. in press (b)] . Zalenskij et at. (1972) studied 
photo^ynthesiB of tundn plaots in Taimyr, U.S.S.IL, and 
found that a deficiency of COj in the atmosphere may re- 
Stiiet plant assimilation, e^ciaily at high light intensities. In 
tlirir ana lys s s maxiPMBD npparmt p h o t o y itttesis was 6 wt 
COj per gram dry weight per hour, which they say iiippoftl 
the concept of low levels of apparent plwtosynthesis in 
Arctic ptants. Data on photoqfnthesis and respiration in No^ 
wcigjan alpijic tundra (Skre, in press) indicate hiiiher maxi- 
mum apparent photo^nthesis in some vascular plants in 
moist. eutropMc oommuidties (partly above 1 5 mg CO} /g/h 
at 15° C and 20,000 lux) early in the growing season. There 
is relatively gpod correlation between production estimated 
fiom karvntlng data. Tamperatures on the day before the 
pbotOiynthetic measurement seem to influence theapptr* 
cut photosynthetic vakies, however O^ygaaid, in prsss). 

Chlorophyll content of tundrs plants mfght be usmI to 
estimate dry matter production after calibration with dry 
weight data (Bliss, 1970). Chlorophyll contents for some 
vascular plant species and tundra vegetation types are given 
in Table 3; obviously, the values expressed as chloro- 
phyll content in mg/m' and in mg/g dry weight are not 
necessarily strongly conelated. Karenlampi (1972) has in- 
vestigated distribution of ddorophyU within the Hdun 
Qadonia alpestn% 

At Point Barrow maxunum amounts of chlorophyll per 
gdiy wslilitoocuninmhklalyOnasun, 1972)Justaslt 
docs at the various tundra sites in Norway (Berg, in press). 
Chlorophyll per m^ reaches its maximum somewhat 
Ittar-dKnit lo^ 25th at Pbint Birrow and about AqguH 



TABLES TotalGMorairfiyllaOTdACniisntofOiflMMM 
Vegetation Typas OtasBulsr Hantt Only) for Tundra 
Ecotystams 



Sites 




OiyVMikt 
(mg/k) 


|W in ill ■ 


uv 




WIHaw 






Wet udge 


760 


8.8 


Wet meadow community 


450 


5.8 


(maximum value) 






MLWaihington^ 






Huth 


540 


1.9 




IW 


2.7 


Wet ledge 


•20 


4.7 








Lithcn heath 


fO 


11 


Dry meadow 


SM 


5.0 


Wet sedge meadow 


SM 


5J 



"licszen, I97J. 
^•BlLss, 1966 
*- Beig, in prcu. 



1st in the dry and wet meadow in Norway. ClUorophyll 
data for mossBS and llGhcna are also aviilabla in Nofwajr. 

Understandably maximiim abovecround biomass occurs 
some days after the peak of dilorophyll per m' . At 
Point Barrow maximum abovegroond biomass was found 
on August 4th in 1970 and a few days later in Norway 

The maximum leaf area index (LAl) of 1 .0 at Point Bar- 
row ooeurrad concttnently with maximum cMorophjrO oon* 
tent perm' (Tieszen, 1972). B!issri970) found lai's 
ranged from 0.94 (heath-rush community) to 3 JO (snow- 
bank community) on Mt. Wasfahigton, although lai of 
most communities was between one and two. In Norway 
LAI of green leaves was 0 J on the lichen heath site at Har- 
dangnviddaand 1.1 atdiawetaedganwadowlneMly 
August 0>aig ef In press). 

Microflora 

The mkroflora may be substantial in some tundra soils. Di- 
rect counts revealed over 10'° bacteria per g dry soil in the 
upper few cm of ftost-boil tundra spot CtUSts and steep 
river banks in Taimyr. U.S.S.R. (Aristovdcaya and Parinkina, 
1972). There were also about O.S X 10' fungi and similar 
amounts of actinomycetes. Low values were found for all 
organi<m8 in hummocky nindra, less than 10* bacteria by 
direct counts. Usually liie microbial activity is rcsincicd to 
surface layera of sod, but in some cases an increase in num* 
ber of bacteria was registered at the permafrost level. In 
Alaska a maximal bacteria count of about 10 ' per g (direct 
oountini) was found diortly after thaw (Brown, 1972). Simi« 



Copy lighted material 



PBOOUCTIVITY OF TUNDRA ECOSYSTEMS 



7 



lar values were obtained by the same methods at Har(laiiger> 
vidda. Nbiwiy, with Mgheit vahm (foamUmt abow 10^* 
per g dry soil) at the eutrophicdiy lOd wetlDtadowt 
(Chaiholm et d., in press). 

At Taimyr cnidc flitiniatM of bactvrid producthity wen 
from 0.05 g to 0.25 g/g soil (Matveyeva, 1972). The average 
number of generations per month was \SJi in the frost-boil 
tundra and steep river banks, but only 1 to 4 in polygon 
bogs (Aristovskaya and Grishina, ISK72). AtHardangervidda, 
Norway, the bacterial dcy-weight biomass ranged from esti- 
mated 550 g/m' (lichen heath) to 940 g/m^ (wet meadow) 
In the upper 35 cm of the soil layer (Clarholm et ai. in pt9u)._ 

Fungi are an important part of reindeer diets in Northern 
Finland (Kallio, personal communication, 1971) and recent 
subjects of biomass and productivity studies. In the U.S.S.R. 
(Stepanova and Tomlin, 1972) dry weight biomass of mush- 
rooms varied between 0.2 g/ha (spotted tundra) and 1 3 
tflat (dwaff-aedRMiiony tundra). At Hardangervidda. Nor' 
way. eslimates of dry weight biomass of fungal hyphae in 
the upper 10 cm of the soil ranged from 50 g/m^ (lichen 
hatth) to 1 10 and 180 g/im' (dry and wet meadows) and 
about 200 g/m' in subalpine bif ch fontt (Uaossen and 
Goics^yr, in press). 

PI.ANTWU<liMAL INTCRACTiONS 

The most strfldog infhienoe of animala on tundra primary 

productivity is the result of small mammal ct^nsumption. 
Dermis (1968) has shown how productivity varies with lem> 
ndng cydea. La., low pcfeniiy produetion in a iMiiiiiing Mgti 
year and high primary production the year before. He also 
noted changes in plant species during the cycling period. 
Selecthre consumption by the small mammds was one fac- 
tor but differences between reproductive potential of plant 
^ecies in dense stands (with high amounts of Utter) and 
mora open vegetation (with leas litter) was abo important; 
such differences in stand density were largely caused by 
aninul grazing. Schultz (1964) reported a SO percent le* 
duction in vigor and yield of plants in one half to two 
thirds of die tundra and a near 90 percent reduction in 
the remainder Airing the 1960 lemming high in Alaska; 
dius resulting in a reducad plant productivity the following 
yew. In die UJSJJL nportnenu on the influence of smaO 
mantmal consumption on vegetation have been carried out. 
When about 1 0 percent of aboveground vegetation was 
oaonmed, increased shoot growth resulted the follovnng 
summer (Smimov and Tokmakova. 1972). These results 
may differ fr«n those cited for the U.S.A. because of the 
lower grazing pressure in the Ruttian experiments. At Har- 
dangervidda, Norway, plant consimiption by smaD mammals 
was about 10 g/m^/year in 1969-70, a small mammal high 
ytu. IMi meant about 10 percent crf'the abovepouod bio- 
mass yns grazed by small mammals in their preferred 
vegetation types. The following year consumption was 



only 3 to 4 percent of the previous summers values (^stbye, 
personal conununiotlon, 1972). 

Large mammals may be important consumer'; of plant 
bionusa in some areas, in Canada the summer removal by 
mmkmc it estlmited to be 1 .5 percent of aboveground bit^ 
mail Each native reindeer at Hardangervidda, Norway, 
consumes 1 ,200 to 1 ^00 g/day on an average during the 
winter months and above 100 g more per day during sum- 
mer (Gam, personal commimication, 1972). Iifoet of the 
winter consimiption is in the windblown plant coinmiuiity 
Loiseleurio-Arctostaphylion with some in the Phyllodoco- 
Myrtillion. The lichens Gadonia milis and Cetraria nivalis 
(Gaare and Skogland, in press) preferred by the animals 
during the winter. The lichen health at Hardangervidda (be- 
longuig to the alliance Loiseleurio-Arctostaphylion) had an 
aboveground y early primary production of vascular plants 
and cryptogams ot above 150 gjm' (the lichens accounting 
for about 50 to 90 g/n*). Ob«iou4y » minimimi of 5J0OO 

of lichen heath is required for one reindeer during the 
seven winter months (November to May) if the Lichen heath 
ii to be kept in ateady state. Thia doaa not tilEe tEmpHng 
damage into account; if this is done, the minimum area 
might be 10 times higher. Makhaeva (1959) found each 
reindeer (dooiettie) in die MiumeMlc eree greeed 65 

each day in lichen tundra. If this estimate is applied to 
Hardangervidda the daily consumption per reindeer would 
be about 20 to 25 g/m* of die Hehen community duting 
winter. 

The influ«ice by invertebrates on plant biomass is diffi- 
cult toaatimate. In die U.SAJI. some estimates of inaect 

consumption of willows arc available (Danilov, 1972 . Bogati* 
chova. 1972); values range from U to 3J percent of the 
green Uomam in tumfai and from 5 to 9 percent on liver 
banks. TTiese values are. of course, higher than estimated 
consumption by p^Uids at Moor House which is 0.1 to 1 
peioant of the aaanil dioot production by CUbm (HodUn- 

KHI.1971). 

ANilMAL PRODUCTION 



The number, biomass and production of bnrertebratea my 

greatly yearly, seasonally and between vegetation types. 
Furthermore, comparisons of values provided by various 
authors are difficult because of variations in measuring 
techniques In the U.S.S.R. differences within one tundra 
zone were someiunes 10 times greater than between zones. 
CoUembola are very important in the Taimyr watersheds 
(Matveyeva, 1972) accounting for about 2/7 of the total 
maximal invertebrate zoomass. At the same site Enchy- 
tneidae account for dbout 1/2 and Nematode 1/7 of the 
zoomass. Tliese two groups are also important in other 
ttmdra communities at Taimyr, in a xeromorphic dwarf 



Copyngliico na.u lal 



8 



i.p.mcijooiAMa 



Arab conununity (mainly Drym) die Oliggchaets lie dso 

important accounting for a zoomass of 25 g/m' (possibly 
fresh weight) out of a total of 40 g/m' . Tipulidae are an 
fenportant group in spots of bare groand and in wet bofi 
(the last site having a total maxunum zoomass of only 
6 g/m^ ). CoUembda are abundant in the dwarf shrub 
communities and grass meadows. The highest invertebitte 
zoomass (90 g/m^) is found in the grass meadow. Danilov 
(1972) reports the total biomass (possibly dry weight) 
of invertebrates (excluding CoUembola and flying insects) 
in Nil and vegetation (Table 4) near Salekhard in the U.S.S.R. 
About 3.5 g.,'m' is the maximum for arthropods and Oligo- 
chaeta in the water banks, while the same groups total less 
than 2 g/m^ in the tundras of tlie area. The biomass, particu- 
larly of sawfly and leaf-bettle larvae, is high in the bushes on 
the water banl(s-22 times higher than in the tundra areas. 
The bioman of flying inawls (not Indwtod bi die above 
mentioned values) is also considerable; e.g., mosquitoes 
along the banks total about 4 g/m^ early in summer (most 
of which ii hter eonnimed by Mfib). Tlieae vaiuea faidicate 
that flying insects as well as invertebrates developed in 
water have to be itKluded to get the total invertebrate bio> 
naas influencing the iMt of the tundra ecoayitem. 

Invertebrate predators have the greatest biomass (56 

percent) in the tundra studies cited above, but this group 
was lelathrely less important on the water banks (29 peieent 
of the biomass) oven tliouidi predatory forms domiruitcd 
numerically (57 percent) in tliis vegetation type. At the 
tundia sites ipiden aooounted fSor about 27 pefcent of th« 
arthropod biomass and 10 percent on the water banks. The 
ra^ecthre peiceatige biomass in the two vegetation ^pes 
WIS 20 and 4 percent for CuaUdat, 11 iiid22pflfenitfor 
TipuHdae larvae and 5 and 22 paieent for budi4wailllng 
Mtwlly and leaf-beetle larvae. 

In the Norwegian tundra project soil invertebrates have 
been studied except for nematodes and protozoans (Kauri 
et al., personal communication, 1972) but quantitative data 
on flying insects are not available. The highest dry weight 
of Enchytraeidae occurred in the middle of August (about 
600 mg/m' ) at the dry meadow site and in winter (above 
2,0(X) mg/m' ) at the wet sedge meadow site. The maximum 
dry weight of arthropods (200 mg/m' by quick4rq»Mn> 
pling) was in the middle of July. The dominating, group it 
that time was Diptera larvae (28 percent), while Acari 



(18.4 percent), Canbidae (12.5 percent). Lepidoptera larvae 

(8 percent) and CoUembola (6 percent) were other important 
associates. Later in the season (mid-September) Lepidopten 
larvae (29 percent) and CoUembola (26 percent) had tbt 
highest dry weight totals, while Acari (17 percent) and 
Carabidae ( 1 2.S percent) contributed about the same per- 
centage to the total dry weight biomass as in the summer. 
CoUembola had a minimum biomass in August, and maxi- 
mum in early spring and late autumn. The biomass of Lepi- 
doptera larvae was minimum in August between maxima 
in July and September. Acari and CoUembola dominate at 
both the dry and wet meadow sites (Acari maximum about 
150,0(X) per m* m August and CoUembola maximum about 
100,000 per m' in July and in early September at the dry 
meadow). Maximum numbers of Enchytraeidae occur in 
late summer (about 50,000 per m^ in wet meadow and 
30j000 petm^tik&v meadow sites). 

The same invertebrate groups were important at tundra 
sites on Devon Island, Canada, as at the alpine tundra sites 
fai Norway (Ryan, 1972), while 80 percent of dio wfl &una 
in the moorlands in United Kingdom consisted of Tipulidae 
lirvie and Enchytraeidae (Cragg, 1 96 1 ). Recognizing the 
great dlflerenoes in fawertebrate fanna the most important 
groups in tundra soil and low vegetation layers generally 
are Nematoda, Enchytraeidae, Acari and CoUembola; at 
certain periods Diptera, Lepidoptera, CtraUdae and Tlpu^ 
Hdae and, fai loake placai, AianhtM «• dio hnpoita^ 

Vertebrates 

Birds have been included in IBP tundra studies in the 
U.SJSJL (DanUov, 1972;Matveyeva, 1972; Vinokurov«f 
nr., 1972), Canada (Pattie, 1972), U.S.A. (Brown. 1972) 
and Norway (Wielgolaski, 1972b). Vinokurov et al. (1972) 
report from 1.7 to 3.7 birds/ha in tundra during the 
breeding period. Matveye«a(i972) reports a density of 2.8 
adult birds/ha in an optimum year. The biomass of herbiv- 
orous birds was estimated to be 246 g/ha, of insectivorous 
birds 628 g/hn and of predators 13 g/ha. Loss of eggs and 
young birds amounted to 25 percent of reproduction. Dani- 
lov (1972) discusses the eating habits of the insectivorous 
birds which diange throughout the summer; e^., tho most 
abundant food for passerines during the breeding season 
was spiders, mosquitoes and fUes, while in August 73 per- 



TABLE 4 Invertebrate Biomass (mg/m^} in Tundra Soil and Vegetation from Southern Jamal (N.W. Salekhard, U.S.S.R.)" 









Arthfopod* 


SawHrand 










Total 


Wormt 


and Fhrini laiect 


1) LanaeinBudMi 


1 Spiders 


CaraUdae 


TipulidM 


Itadia 


1.7S0 


1.190 


S90 


30 

650 


160 
150 


115 
65 


65 
350 



Copy lighted material 



PRODUCTIVITY OF TUNDRA ECOSYSTEMS 



9 



cent of the food wai sawfly larvae. Aithrupod biumass 
oomuoMd by biids wtt aibmt 3 kg/ha in tandi* and 1^ 

tween 6 and 1 2 V.g[ha in wet areas close to rivers and lakM> 
Even when the young birds wett fairly large, not more 
than alMut 2 pwemt of avallabte food wu utltt^ 
birds, and their influerwe on the invertebrate population was 
insignificant. Great annual variation it found in the avian 
ftuna. The variation pardy ftdlowi the 3 to 4 year cycle of 
small mammals, but the bird cycles are not as regular and 
vaiy with the species (Vinokurov el al., 1972). The cycles 
of avian piadaton ta tundra areas, anch m maw owb and 
jaegers in Alaska, mostly follow the small mammals cycles. 

The yearly fluctuatioot in anaU ouuiunals it liigtu Thorop- 
aon (19SS) says that kmndngdanitiBa may encaad lOQ/lia 
in peak years at Point Barrow, Aladca, nd Vinokurov et at. 
(1972) reports fluctuations from zero to 725 lenunings/ha 
in inorable habitats at Taimyr. At Hardangervidda, Nor* 
wiqr.93 small mammals/ha (mostly Micro tus oeconomus) 
were caught in September 1970, while only 2 were found 
in September 1971 (0stbye, personal communication, 1972). 
The biomass of small mammals in September 1970 was es- 
timated to be 3 2 kg.'lia at Hardangervidda while that of 
1 19 lenunings/ha at Taunyr, U.S.S.R. in 1967 was 8.3 kg/ 
ha (Matveyeva, 1972). In Canada the 1970 standing crop of 
small mammals was low, i.e., only 4.6 g/ha for lemmings in 
August (Speller, 1972). At Point Barrow, Alaska, an in- 
crease in brown lemmings oocuned over tiie winter of 1970- 
1971. and in June 1971 theasttanataddandlywat 75 in- 
dividuals/ha (Brown, 1972). 

The rde of lanuningB in tundra acoayslans b the subject 

of much additional study As an example, a population 
dynaroKS and feeding model is being constructed which 
combines data on physiology and behawtor (sudi u food 
and habitat selection). In Canada small mammals prefer the 
plants Dryas integrifoUa and Stdix arctica. In Norway Dryas 
oetopeitda and Afo herbaeev are favored as food. Ilie 
small mammal production from September 1969 to Sep- 
tember 1970 was 2,650 kcal/ha with a plant consumption 
of 366,000 kcat/ha/year. Arctic fox po|Nitatlons are depen- 
dent on the number of lemmings (Bannikov, 1970; 
Vinokurov et a/., 1972). The latter authort reported the 
maxbmim density of arctic f<»ces to be 0.032 per ha; Banni- 
kov (1970), using data from various authors, gives values 
of QXil 1 to 0.03S per ha with increases in population from 
wast to east due to hi^er quality habitat. The Dwim 
Uandaielic fox population was estimated to htwanaver- 
agiB bloniass of 1.S g/ha (Riewe, 1972). In the same area the 
standfalgcropof muskox averaged about 250 g/ha for the 
thieastanmer months (Hubert, 1972) 

The reindeer population at Tai]nyr is estimated to be 1.3 
individuals/ha with a biumass up to 1 .000 kg/ha (Matveyeva, 
1972). Reindeer populations at Hardangervidda, Norway, 
fluctuate widely. In 1970 the population was about 3 in- 
dividuals/km^ ; only about 1/10 ol the area was uselui as 



winter grazing and, consequently, the lichen heaths were 
higldy oveigfazad doling wtatais. hi die utetar of 1970 to 
I')?! a heavy ice crust covered many of the lichen heaths 
drastically reducing the area available for grazing. A reduc- 
tion of Ihn latadaar popidMloa to about 1/4 of its ctdier 
size followed. 

Decern |}otition 

iinergy flow diagrams have been constructed for tundra 
ecosystems (e.g.. see DaM and Gore, 1968; Wss, 1972; 

Brown. 1972). According to Bliss (1972) the plant-soU 
oigiBnic-decoropoaer cycle seams to be the main pathway, 
wWi herbivores and eamhrores being only minor pathways. 
Heal (1972) also stresses this for the moorland sites in the 
United ICingdom. Some of the IBP tundra data have shown, 
however, that many soil invertebrates are important for 
decomposition of organic material. 

The decomposition rate of Utter in tundra has been 
studied by the litter bag technique ( HeaJ, 1972J. In the 
moorlands of United Kingdom about SO pafcaot wi<|^ 
loss o^Calluna shoots and Eriapharum leaves occurred 
over a five-year period. In Norway a weiglu loss of above 
74 percent of Gmsc nigra leaf Utttr was found ovef a period 
of one year, with lower values for most other materials; 
while in Sweden the decomposition rate for Rubus was 
about 2S percent fai the first year (Roanvall efaf bi prau). 
A study of cellulose decomposition at different soil depths 
indicates tiiat the rate of decay in the surface 2 cm may be 
5 to 6 tbncs Idgher than the rate of decay of the same 
material at 20 cm depth when water is not limiting the 
piO0SBi(Heal«/a/., 1974; Berg a/., in press). 

IMITRIENT RELATIONSHIPS 

Even though knowledge of energy and caiboo flow has 

been the main aim of most iBP-tundra projects, emphasis 
hat also been placed on luiuient cycling. Studies of nitro- 
gen fixation liave been foremost because of the liypotiiesis 

that N limits productivity. In Norway both asymbiotic 
and symbiotic N-fixation (mostly lichens and blue-green 
algae) was found at most tundia sites. A rou^ estbnate sets 
N-fixation at up to 1 to 2 g/m^/yr (Granhall and Lid- 
Torsvik, in pimb). In Sweden values up to 5 to 6 g/m'/yr 
wata found fix Uuefrean algae (Graidiall and Sdander, 
1972, 1973; RosswaU, 1972). In Finland the MmNepkn- 
ma arctkum. Sohritta crocea. Peltigera sp. and Stereocaulon 
sp. are important in N-flxation (Kallio and Suhonen, 1972; 
Kallio and KalUo, in press). Solorina crocea seems to be flie 
Uchen species in Norway with highest N-fixation. From 
Point Barrow, Alaska, Brown (1972) reports N-fixation of 
about 15 Aig/m^ /hour (about 20 mg/m'/year) in areas with 
Peltigera aphthosa On Devon Island, Canada, considerable 
N-fixation was found in mesic meadow soils with decrees- 



Copyrighted material 



10 



M.wntaom> K i 



ing amounts in hydiic meadows and on beach ridges (possibly 
too cold and too dry respectively). Soil microorganisms 
appear to be the principal nitrogen fixers, although Nmtnc 
eomimuu h common in the meiic meadows (Stulz, 1 972). 
In the UiSJSJt. N-fbcing blue-green algae, such as Nnstoc 
mkmscopica, are also found in tundra areas along with the 
N-fixing Cyanophyceae (NovichkovaJvanova, 1972). The 
algal flora of tilled areas was found to be twice as rich as 
the flora of virgin tundra. 

Besides these intensive studies ot nitrogen, chcmicul 
analyses of prec^tition, soil ground water (input and out- 
put), soil, various components of plants and animals have 
been performed for several elements at many sites. Ferti- 
lizer experiments combined with lysimeter studies are 
carried out at some sites (o obtain better values for ntCS 
ot nutnenl cycling in tundra ecusystenos. 



ACKNOWLEDGEMENTS 

I would like to lhank the individual workers in all IBP tundra 
projects who lunlnbuled ideas lor organization, as well a> informa- 
tion and data, to this paper, and aUo to thank (he membenaf titt 
IBP Tlmdra Biome Swering CommiUM, wliich iwie««l the paper 



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Skn,0. in pinu. CO.. <xchangc in Norwegian tundra plants 

•tudted by infr^rt-d jn.ilv/t'r tci hnmuc. In V W, WIelgolaikl 
(ed.) Fennoscandian Tundra Ecosystems. Part 1. Plants and 
MicroorganismH. Slplimw VMlg, Beill»-lMd<MMV 
New York. 

Sntaw; V.S..and S. G. Tokmakova. 1972. Inflnence of consumm 
on nnlniii piqrtootnoiis prodocdon vuktkm, p. 122-127. In 
F.E.inil|iolaiid eadlh. Roeiwill (cd.)ftooeett«f iV. Inl«> 

national Meeting on the Biological Productivity of Tundra, 
Leningrad, Oct. I97I. Tundra Biomc Steering Committee, 
Stockholm. 320 p. 
SpeUer, S. W. 1972. biology of /)(crosro/>.fj( xn>enlamfjcut on True- 
love Uwland, Devon Island. N.W.T.. p. 257-271./* L C BKh 
(ed.) Devon Uand I.B.P. project, lii^fi aietie eeoqntani. Ftojeet 
npovt 1970 iiid 1971. Dept. of Hot. Univanity of Albarta, 
Canada. 413 p. 

Stepanova, I. V.. and B. Tomilin. 1972. Fungi of basic plant com- 
munita-s in Taimyr tundra, p. 193-198. In F. E. Wielgolaski and 
TIl Rosswall (ed.) Proceedinp IV. Intemational Meeting on tiie 



Biologleal Prodnetivliy of Ttondn. Leningrad, Oct. 1971 . Ttondn 

Biome Steering Committee. Stockholm. 320 p 

Stutz, R. C. 1972. .Sitroncn fixation studies on Ocu.'n Island, p. 
252-256. /n L C Bli^^ l< iJ.> Devon Island IBP project, high 
arctic ecosystem. Project report 1970 and 1971. DepL of Bot., 
University of Alberta, Canada. 413 p. 

Svoboda. J. 1973. frimaiy piodnctioa of pint comnMiniliei of Oie 
Thialave Lowland, Devo* bland. CMMda-beach ridgaa, p. 15- 
26. In L. C. Bliss and F. E. Wielgolaski (ed.) Primary Production 
and Production Procc$.ses, Tundra Biome. Tundra Biomc Steer- 
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Thompson, D. Q. 1955. The role of food and cover in population 
fluctuations of the brown lemming at Point Barrow, Alado. 
p. 166-176. In i. B. Trefeiiien (ed.) Ttaaaactiona of the 
Twamtodi Mm* Anwikan WMUfi* Coafn Maidi 14-M. 195S. 
Honlfcal, Qnebee, Canada. WNUfe Manaianent InititniaL 6S3 p. 

Hesten, L. L 1972. fhotoiyntlierfi in rdalfon to primary produc- 
tion, p. 52-62. In F. E. Wielgolaski and Tti Rosswall (ed ) Prcv- 
cecdings IV. International Meeting on the Biological Productivity 
of T::iKiM i.n^ngrad. Oct. l971.TnndiiBionwSlooiinBClain> 
mittee, Stockholm. 320 p. 

lUdlomilOV, B. A. (ed.) 1971. Biogcocenosis of Taimyt tundrj and 
tlMir pcoductivity. fvbL Houae "Nauka," Leningrad. 237 p. 

VaMWevAaya. V. D., and L. A. Giiddna. 1972. Oiganie carbon i»> 
aerves in the conjugate eluvial accunnriative landicapei of Weat 
Taimyr (Station Agapa). p. 21S-2l8./nF.E.Wlelgolaikiand 
Th. Rosswall (ed.) ProcccdKi^:\ iV International Meeting on 
the Biological Productivity ut 1 undra, Leningrad, Oct. 1971. 
Tundra Biome Steering Committee. Stockholm. 320 p. 

Vinokurov. A. A.. V. A. Orlov, and Yu. V. Okhotsky. 1972. Popu- 
lation and faunal dynandei of venehnlaa in tnndm MoMHOM 
(lUmyr). p. 187-189. /n F. E. WMfeolaAi nd Th. RmhiiII 
(ed.) Ptoeeedhigi IV. bternatiaaal Maetim «• <k* Bloi«|ieal 
Productivity i.rTuiidi:!, I etiingrad, Oct. 1971. "nindin Blonin 
Steering Committee, Stockholm. 320 p. 

Warren Wilson. I. 1957. Arctic plant growth Adv Sci 13 383-388. 

WMgolaiki, F. E. 1972a. VageUtioa typei and plant biomaaa 
in inndn. Alotk and Alptea Ka8.4:291-30S. 

WallBladd, P. E. 1972b. Itadnolion. «Mi|p flow and aatiiMt 
qrcflng dtroagh a Mrreitrial eooiyitam at a aldtnde area 
in Norway, p. 283-290. /" I F Wicipola^ki and Th. Rosswall 
(cd.) Prixecdings IV. InternaUunal Meeting on Biological 
Productivity of Tundra, Leningrad, Oct 1971. Tbadn BlonW 
Steering Committee. Stockholm. 320 p. 

Wldtabald. F. E. (ed.) in pteta (a). Fennotcaadian Tundra EcogaHm a . 
l!wM I and 2. ^rinpir Vmliv. Baill»4Mdalbeic-Ncw York. 

Wldgoiaiki, F. E. In preu (b). Mnwy prodnctivHy of alpine 

meadow communities. In F. E. Wielgolaski (cd.) rcnn*i';L:indi.in 
Tundra Kcotystems. Part 1. Plants and Microorganisrai. Sptmgcr 
Verlag, Berlin-IIcidclbcrg-Ncw Vsirk 

Wielgolaski, F. t... and S. Kjelvik. In press. Plant biomass at the Nor- 
wegian IBP site* at Hardangcrvidda 1969-1972. p. 1-88. At 
R. Ytk (ed.) IBP in Norwair, MedMidaairi llMull*.Sactle« 
n-UM Grating profect Hardangervidda. Botanical In w a l lm - 
tions. Norwegian National IBP Committee. O'slo 

Wielgolaski, F. F.. and T. Rosswall (ed l 1972 HiiKTccdings IV. 

IntCnutlunaJ ML-eling on the Biologicii Pruductivity of Tundra, 

Leningrad, Oct. 1971. Tundra Biome Steering Committee, 
Stockholm. 320 p. 
ZaleiMMi. 0. V., V. M. Shvataowa. and V. L. Vosnaaianiky. 1972. 
Iholoajrndiaria in aonio planla of Waatam Tkiniyrt p. 182-186. 
/N P. e. WMlolaiki and Th. Rosswall (ed.) Proceeding* IV. 
Intemational Meeting on tite Bioloficai Productivity of l^indra. 
Leningrad, Oct. 1 971. Italdn BtoOM SlaaiingCoMniilloa, 
Stockholm. 320 p. 



Copyrighted material 



PRODUCTIVITY OF 
THE WORLD'S 
MAIN ECOSYSTEMS 



L. E. RODIN, N. I. BAZILEVICH. 
and N. N. ROZOV 



The total phytomass ol iU6 terrestrial suii-plant formations, 
grouped into biocUnutic aim and thermal belts, has been 
calculated along with estimates of annual productivity. The 
total phytomass of the land is estimated to be 2.4 X 10'^ 
metric tons diy weight. The bulk of thb oi|uie nuia ia la 
the tropical zone (56 percent), followed by the boreal (18 
percent), subtropical (14 percent), subboreal (12 percent) 
and pdar (1 pefeeiit)zoaea. Thetnajority of phytomaai b 

concentrated in forests (82 percent). Regularities of phyto- 
mass distribution in the world's oceans resemble those on 
the bod (iltentlon of belti with high and low amounts of 
phytomass; abundance and concentration in the areas of 
^clonic cycling of atmosphere and waters), but there exist 
some pecularities pertinent only to the oceans (nuutimum 
accumulation of phytomass in temperate latitudes and the 
shores). Total phytomass in the world's oceans amounts to 
1.7X 10* metric torn, which i« about I5j000tbnes smaller 

than that of the land. 

The total primary production of the land is estimated 
to be 1 .72 X 10" mettle tona/year. The tropical belt pro- 
duces 60 percent of this total; subtropical, 20 percent; sub- 
boreal, 10 percent; boreal, 9 percent; and polar, 0.8 percent. 
Poreits prodooe 49 petoent of primary productioa of the 
land. The total primary production of the oceans is esti- 
mated at 4.7 to 72 X 10'° metric tons/year (Steemann et 
al., 19S7; KoblentiMiihke, 1968; Bogorov. 1969). Hence, 
the oceans contribute approximately one-third as much 
primary production as do terrestrial plant communities. 
The total primary production of the earth is calculated as 
being 2.35 X 10" metric lioaii/!y«ir of dry ocgmie mattar 
a«blel). 

13 



As the most vital ol the zones enclosing the earth, the 
biosphere accumulates and ccmverts the extremely power- 
ful stream of incident solar energy into the chemical 
energy of organic compounds. This conversion is accom- 
pUriied by an or iMdc matrix that has comtuntly repraduced 

and perfected itself in the process of evolution over the 
thousands of millions of years of geological history. 
Some flfky yean afo, V. I. Vemadikl (1926) wrote: "Un- 

fortunately, the data currently available [are] still too scaioe 
to pinpoint the exact share of green plants in the earth's 
totdorganie matter. For the present, we have to mdce the 
best of rather inaccurate figures in an effort to sixe up the 
phenomenon in hand." Today the situation has radically 
changed with the development of plant and eoQ map*, ttie 
accurate calculation of areas within particular soil-vegetation 
formations, and the determination of biological productivity 
for many of tiiese formations. It has been shown that the 
earth's living organic matter (biomais) is dominated (99 per- 
cent) by autotrophic and photosynthesizing organisms. As 
a result of these developments it is now posrible to duff- 
acterize global biotic productivity based primiri^ OpOft the 
primary production of green plants. 

Shoe orgaidc natter Is capable of reproduction, growth 
and accumulation only for a delimited period of time, it is 
fair to assume that phytomass reserves are correlated with 
aniuiil IncNmenl.* Both paiameteismay be caleuhted 
either on a unit area basis or as total standing crop for the 
entire area of a given vegetation cover type. The geographi- 

* Hneaftei Bgian for piiy tooMB and aaniiil incnment iiifi»Httag 
die abow^ and vataiieuiid parts of plaats wll be i)«an as diy 
Wright. 



Copyriytinju rriaicrial 



14 L.E.HODIN«til. 



TABLE 1 Anm, PhytMnm, ind Prinwry Froduetion of Hw EirA'i Vagttslion Zona 



Tbermu Zoti 


Aim 




Phy toman 




Primary Production 


Ifr n 




ID M 


% 


10^ m 


ft 


PoUr 


8.05 


1.6 


13.77 


0.6 




A A 


Boreal 


23.20 


4.5 


4i9M 


18.3 


l3al7 




SvMmnal 


tlSi 


4.S 


27&67 


11.S 


1 r«7r 


imf 


Subtropical 


24.26 


4.8 


323.M 


U4 


34.55 


14.0 


Tropical 


55.85 


10.8 


1.347.10 


56.t 


102.53 


44.2 


Land (without gladeil^ 














lakes, and riven) 


133.4 


26.2 


2,402.5 


100 


171.54 


73,8 


Gketefi 


13.9 


2.7 


0 


0 


0 


0 


Laket and riven 


2.0 


M 


0.04 


<0.01 


1.0 


04 




149.3 


793 




100 


I73J4 


74.2 




MIjO 


7M 


ai7 


<0.001 


<0U» 


2S.8 


TteMMk 


S1Q.3 


100 


2^71 


100 


33X54 


100 



TABLE 2 Minimum and Maximum Phytoman Reserve in the Zonal Type* of 
Soil-VegeUtion Fonnatiora of Different Thermal Belts and Hydrothermal Region* 
(tn/lw.dfy«wHhtl 



Thermal Bell 


Type of Soil-Vcfietation Formations 


Hydrothermal Regions 

Humid Arid 


Falar 


Pillar dcsc.-t 

Tundra on tundra soil* 


5 
28 




Bonal 


Needle foteat of Om northetn taiga on 

Naedto teift of llw middle tajp oil 

podBoUc aoOf 
Needle forest of <hi: MHiiiani ta|ia 0* 

turt^odzolic K>dt 

■rndbaf fonat ON iny fomt Mlib 


ISO 

«0 

300 
370 




SaMoiMl 


Broadleaf forest on brown forest soils 
Semldunb deaeit on giay-brawn deaert aoila 


400 


4.3 


Subttofkal 


BfOadleaf forest on red and yellow aoila 
Dceert on subtropical desert lolli 


450 


10 


Tropical 


Humid tropical forest on ted ferralitic soils 
Oaaert on tfonlcil deiatt aaDt 


650 


IJ 



cal patterns of phytomass (= plant MoiinM)dJitillNitioa per 

unit area for the major types of terrestrial vegetation al- 
ready have been tunuiuuized and mapped (Rodin and 
BuilMlch. 1967: Itailwich ud Rodin. 1967). 

The data on geographical patterns show that each of the 
earth's thermal zones is associated with a particular soil- 
vegelation formation with characteriitic biomm. Going 
from the polar through the boreal, cool temperate or "sub* 
boreal," to "subtropic"* to tiopict thermal zones, the 
noffi bttvwMi maxloiiun and nUninttnn Iriontaii increucs 

* U.. warn lenipHaM In ontamaiy Ea^ mage. 
tlMMtasaqnatoiM. 



becauM of an increate In absolute inaxbnum and adocmae 

in absolute minimum values fTable 2). This phenomenon 
is a»ociated, on the one hand, with changes in tiie effi- 
ciendes in energy fixation along pole-ti>^aator gradieata 
with varying moistarc supply and. on the other hand, with 
genetic properties and Ufe forms of the plant communities. 
WItMn fh» bitcasonat aoO-weiaiation formatiOM thaaa pat- 
terns are manifest with the same prominence, yet upon 
them ate superimposed the effects of additional factors. An 
axanipla la the geodianiical ae<|iianoa of landacapaa wMch 
involves the redistribution of energy resources as well tt 
water, nutrients, anaerobiosis, salinization, etc. Thus, In 
aamiadd and arid t^ons, floodJand fionnatioDi yield large 



Copyr^hted material 



raOOUCTIVITY OF THE WORLD'S MAIN ECOSYSTEPMS 

quantities of bionms, while saline and alkaline areas yield 
very maU cpnuitltles. In cdcobting the total global temves 
of biomaw, surface areas were categorized accurJing (o 
suiuble types of soil-vegetation foimations using the soil 
and continental vegetation maps from the Physico-Geo- 
gmphJcal Atlas of the World fSenderova. 1964), These data 
WM* lynthesized into 106 soil-vegetation formations which, 
iit tum»««fe daaed widi thennl xoiiMiiidliydrothifiMl 
(biodlmatie) aibaxiBi (Tiblt 3). 



15 

Since our primary objective is to estimate the earth's bio- 
logical potentid, calculations of bkoun and annual Incre* 

rncnts assumed that the vegetation cover existed in its 
precultivated or natural state (not exceeding 15 percent of 
the tfrtal drytand area) or prelogging statua. Beridea the 
materials furnished by L. E. Rodin and N. I. Ba^ilevich 
(1967), the authors uied extensive new data on produc- 
tivity of vegetatloa ooim obtained dining the hternitionil 
molflsical Ftapimnt (Molchuiov, 1964; BazlleviGli, 19ti7; 



TABLES niyienMMan4AnnuriPrlm«vP»odueiionol*eEaHh'aLandAi«« 



Phytomass Production 
Thermal Belts, Biodim«tic Regiom. and gel-VegelaliO«i FwrnaltalS IQi* t t/ha Ifli* t 



ralir deaertf (Arctic) on pdyfonil ud oflMr Airae Mis 


S 


353 


1.0 


70.6 


Tundrn on t'jndrj rIcv soil< 


28 


10417 


2.5 


939.0 


Bogs (pijUr) on bij$ pcnualrosl ioUs 


25 


470 


2.2 


41.4 


Floodplain formations 


10 


12 


1.7 


2.04 


Mounuinout potu d«iert foimatioiu on Arctic mountain toflt 


8 


352 


1.5 


66.0 


Mountainoui tndn ftomaliaiis m nMumafaHaHlia aeiit 


7 


2,062 


0.7 


206.22 


TOTAL 


17.1 


13,766 


1.6 


1425.26 


JkwiMfMr. himMmiditmlkmiiingkm 










MaiitinM haibweonfroicst fonnBtiom on voleaalc ath 


too 


I.3S0 


IftO 


13541 


Open forcit-tundra woodland and norlhem taiga forest on gley^odaolB ioBs 


125 


11,000 


S.O 


AAA A 

440.0 


Same, on gley-permafrott taiga toils 


180 


1 2 . 1 90 


4.0 


487.6 


Middle taiga foreit on podzolic soils 


ZoO 


92,846 


7.0 




Same, on pemiafrott taiga soils 


200 


49,260 


£ A 

6.0 


1 .477.8 


SotttiMra taiga and miXMl broadleaf and needle fovatt on tuifpodzoUc soils 


30O 


9S,i46Q 


7,5 


2,386.5 




350 


13,755 


IQiO 


9A9 A 

393.0 


aam^oniMftcaKaieowaMnnrguysais 




SA 

1II199S 


lA A 

10.0 


4A1 A 


snWt on wgi nog sow win DOgs 


eA 
au 




A A 


941.2 


SmalMeaf for^t on gray and gray solodtaad feiHl SOOs 


200 


4,j4U 


A 

8.0 


1 at ^ 


Broadleaf forest on gray fomt loito , 




in 


fi A 


OCA 


Bogs 




i,oyl 


i.b 


Ton ■> 


Floodplain foiroations 


eo 


3,339 


6.0 


355.8 


llomtiiiHaliB tansla on mountain podaoUeaols 


170 


45.832 


6.0 


1.617.6 




ICO 


48d640 


5.0 


1420.0 


MbiiMsln naidain on ffagr flMutdn faiMt sols 


300 


7460 


7.5 


189A 


Mountain nnedows on mc—lata maidoiw sola 


35 


5412.5 


12.0 


149aA 


TOTAL 


189.2 


439.06I.S 


6.5« 


1S,173J 


Subbortal belt, humkl regiont 










Broadleaf forests on brown forest soils 


400 ' 


99,400 


13 


3,230.5 


Same, on rendzinas 


370 


999 


12 


32.4 


HoilMoeoBS piaiiie on nmdow chemoniDlilw soiii (biunlseins) 


35 


1,984.5 


15 


850.5 




300 


9480 


13 


4294) 


Bogi 


40 


64 


25 


40J> 


Floodpliin foiBiatioaa 


90 


1.782 


12 


2374 


Mountain foftet on beam aouBlaia fanst nSi 


370 


139.453 


12 


4,522.8 


TOTAL 


342 


253.582.5 


116 


9.342.8 


Subboreal bell. semiariJ regiont 










Stappe OB typical and leacbed chemozcmi 


25 


l,607.i 


13 


1.355.9 


Saaw. on onUnuy and sondkein cbainoHBH 


20 


2.9410 


8 


1.176.8 




20 


5000 


8 


2004) 


StappifM fomatiant on solonets 


16 


104.0 


5 


32J 


Halophytic formations on solonchak fin steppe) 


12 


7.2 


4 


24 


Psammophytic formations on sand (in steppe) 


IS 


108.0 


8 


484) 


Dr> siL'ppc on dark t.hestnut soils 


20 


1.480.0 


9 


666.0 


Desert steppe on ligtit chestnut soils 


13 


1,574.3 


5 


60SJS 


Dry and desert iteppo on oheitaut ind lolo— ts coinpliws 


14 


938.0 


S 


335.0 


gainOiOnioUiMls 


14 


296.8 


5 


10641 



Copyr^hted material 



16 

TABLE 3 (continuad) 



L. E. ROOIN M al. 



Production 



Thermal IJ«lti, Bioclimiitu Regions, and Soil-Vegeuiion I'ormatiuru 


tflu 


10* 1 


t/ha 


10* t 


Halophytic fomutions on tolonchalc (in dry and deiert steppe) 


2 


15.2 


0.7 


5.3 


Pummophytic rormaiions on sand (in dry aid daiHt iMppe) 


IS 


213.0 


6 


85.2 


Herbaceous ttog on meadow-bog soils 


15 


85.5 


7 


39.9 


Floodplain forraatioas 


vD 


2,280.0 


12 


342.0 


Mountiin dry siqipe on mountain cfaeitnut soilt 


19 


1,245.0 


7 


581.0 


Mountain tteppe on nooataiB chemotems 


29 


S72.S 


1 A 

10 


229.0 


Momtain mMdow tUft* mi wbalrinn imNialaiii ibmJow atsppa mAi 


29 


lailS9<0 


II 


■ HA A 


'■WW * ¥ 

TuTAL 


20.1 


|D,S94.V 


o *1 


VJOJT.V 


Subboreal heir, arid regions 










Steppificd descri un brown semidesert soils 


12 


1,6%. 8 


4.0 


J65 6 


S^nu', un b;i iwn-soil md WkNlMlCOinillCIIH 


1 A 

10 


407.0 


3.5 


] 4J _^ 


Sante, on solonets 


9 


126.0 


3.2 


44.8 


Dttut on pvy-biown deiert toils 


4.S 


617.9 


1.5 


205.9 


AttflUBopliyiic fomaiioiit on uad (in dsMcO 


30 


2^.0 


5.0 


414.0 


Dwrt OB takyr mOs wd takyii 


3 


30.3 


1.0 


12.1 


Halophy tic fonnatlow on wlcxilialt (ia daitn) 


14 


32.7 


0.5 


10.9 


Floodplain formatiom 


M 


1,088.0 


13 


176.8 


Mountain desert on brown mountain HHlldaacrt tOl$ 


9 




3 


105.6 


Same, on desert highland sods 


7 


1,437.8 


1.5 


308.1 


TOTAL 


11.7 


8,234.3 


2.8 


1,986.3 


SUBBOREAL BELT TOTAL 


123.6 


278,679.8 


7.9 


17,969.0 


Subtropical belt, humid regions 










Broadlaaf fomt on rad wHa and yellow wflt 




flu 0£c 


2U 


% OKA A 


Santa^ an lad^otofad fcndiiBai and 1am fom 


9mf 




to 


2f9*« 


HertMceous prairie on reddish black soils and lubnaaw 




1,42a 


19 




Broadlcaf forest, swampy, witli small bogaiaaa 


4Wl 


3, two 


22 


2/ /.2 


Mt .idiiUf -Dog and t>og loiniailuiii 


^UU 








t'loodpLam fomiatioro 




1 /,UMJ 


^A 


T T> H A 


Mountain broadHtf nMMS M BMWinfUn yMow warn ana iw niu 


410 


1 AIT 


IS 


4,3oo.O 


TOTAL 






23.9 




Xvrophytic fomt on brown soils 


I'M 


^■t AOS 




2iS4SaS 


snrut>4teppc lormations on gray-orown foiu 






in 


2MV 


Same, on gray-brown soloiu'ts M'iK with ^m.il! ^oiunt-Ms araaa 


lA 


1 CA 


o 




Same, on subtropical chernozcmlilie and coalesced soils 


1 c 


1,187.3 


Q 

0 


ISA 

Soil 


PsaiTunophytic formations on sandy soils and sand 


20 


102 


5 


23.3 


Halophy tic focmationi oo Kdoncnak tout and solonchak 


1>9 


10-95 


0.5 




Roodiplaiii fbHMtions 


250 


15,725 


40 


2,316 


Mo— mnnawptydeftweatonbiownnwwntainaoMa 


120 


a6i032 


13 


2,90b.S 


Mousrsui inni04nppc lonnanoM on gnyHMww mounuB acma 


30 


1^479 


0 


3944 


TOTAL 


98.7 


Sl,m4S 


13J 


II>M«1S 


Subtropical bell, and rt gians 










Steppificd desert on sercv'etn<; jnJ meadB» WBW idli 


12 


2,3 76 


10 


1.980.0 


Dmert on subtropical desert soils 


2 


857.8 


1 


428.9 


Pttmmophytlc formation! on Had 


3 


362.5 


0.1 


18.75 


Daaart on takyr aoOt and takyn 


1 


14.7 


0.5 


7J5 


HalflpkyHe fomatfaMB OB laloaduk 


1 


21.0 


0.3 


4.2 


FkwdVlaln famutlons 


200 


1(71010 


90 


3.951AI 


Moon tain deaart on mountain seioXHM 


15 


915.0 


12 


TjZ.O 


Same, on ubtiaflcalaaiiNaiBdaaiftioflB 


• 


54 


1 


IDA 

I H.u 


TrtTAl 




13 SRI 


1% 


7 140 7 


SUBTROPICAL BELT TOTAL 


133.5 


323395.4 


14.3 


34^3.15 


7>a|p<o>' Mr, humid rtgiont 










Hamid everfreen fomt on lad-yaiow ftnalMc toll* 


650 


560,950 


30 


25.190 


Samo, oa darlMod wilt 


600 


U320 


27 


531J 


SaaaomBy liuaild avaifiMn fonat and waosduy (dlfnai 










savjnna on red fLTialitic soils 


200 


175.720 


1« 


14,057.6 


Sanic. i>n Hj\:k. tropical toils 


80 


1.128 


15 


211.5 


Huima uvei^ rcen swampy ftnaaloaltoialllieiiqr ma 


soo 


112,200 


25 


5,610 


fio^ formauoM 


300 


19,920 


150 


9.960 



Copyr^hted material 



PRODUCTIVITY OF THE WORLO^ MAIN ECOSYSTEMS 

TABU 3 (eontiiMHcl) 



17 



Thermal Bcltj. Bioclimatic IUiiam.aildSoi-VfK»l«lk)a FoonatkMH 


t/ha 


10* t 


Productiaa 


10* t 


Plndvlnlain fi^rmationt 

C l^n^^U L/ 1 iui Ilia Llwll^ 




250 


29,375 


70 


8.225 


Msncmvp fnr<*<t 




130 


6.214 


10 


478 


Uiiniul tfftfwiu*al nkniintavn fnwtiMi nn nMWw^lmif fiMraUtl^ itinui 


wmmh HJfi* 


700 


169.330 


3S 


8.466.5 


SaUmMMuMt^ IHUHW UVpiBS limiMS^M HHWH «■ m WHUIMi III 




450 


79415 


22 


3.8874 


TOTAL 




4404 


1.1M.172 


29.2 


77.ai7.9 














Y*T/ 1 1"! K k.r t ii r-irj'it [1(1 r<' r r*i J i t i 7 K f i i U,' fl f cVl - f .'■(I Ci"!!!!; 

Acr<ifiri> LR loit^i uii I (. iiuu 1 1/ t-u uinwniMi i^-u m.>ii> 




250 


115,675 


17 


7.865.9 






40 


26.188 


12 


7,856.4 


$unc> on tropic^ blsck soils 




30 


e.190 


11 


2.255.0 


Same, on Uopic&l solooeuaofls 




20 


470 


7 


164.5 


Mcaaow ana swamp nvim w icmPuPBQ i«o mo nmvov 


Milt 


60 


5.364 


14 


1.251.6 


Floodpliiii f ofBidiMt 




200 


4v«20 


60 


1.3260) 


XlMi^liy tic iiMMtiltt fbiMt Oft 




200 


9.940 


15 


745J 


Mountain savattmoaieMfOWiiiiKMiatakiiolf 




40 


3.752 


12 


1. 125.6 


TOTAL 




107.4 


171,959 


14.1 


22.590.5 


iniipicvi c>cu, flrlu rtgtOftS 












Dmrtlike savanna on reddish-brown soils 










1 7tA n 

I|/ lO.U 


DMBVt on tropical desert soils 




l.S 


70^95 


1 


467.3 


FmnrapDyiic lonnaiwni on suitt 




1.0 


282 


ai 


28.2 


Dmrt om toopinl dNkwai «olb 




1.0 


21.C 


02 


4J2 


Hllflpliy4c KonutiQM on MtaMhik 




1.0 


IIJ 


ai 


1.15 


FloodpteiA fgoHtlMH 




ISO 


t.S0O 


4ao 


400lO 


Mounuin desert OB Mpled BOOBliii daHrt Hli 




I 


€U 


0.1 


6.26 


TOTAL 




7.0 




2jO 


2^23.23 


TROfflCAL BBLT TOTAL 






1.M7.14445 


1S.S 


102.59143 


Earth's total bad am («fliMNitilaeiHi,sliMnttthlHi) 




180.1 


2.M2.S474 


12J 


171A42J6 


Glacien 




0 


0 


0 


0 








40jO 


5 


1.000 


TOTAL FOR AIX CONTINENTS 




1«0.9 


2,4in;StT.4 


11.9 


172.342J6 



PyivdMnko. l967:GliIiiroverar., 1968; Dflmy, 1969; 

GoUeye/a/., I969;Jenik, 1969. Kira andOgawa, 1969; 
Whittaker, 1971; Bazilevich and Rodin, 1971 ; Soil regimes 
and proceaet, 1970; Biological productivity and regimes 
ofsoUs, 1971). 

The total land ptay tomaat naeives of the earth aie esti- 
iitttod «• 2.4 X metric tnu. 11w bulk of tfiis biomiss 
ooeun in die tropical zone- 1 .35 X 10'^ metric tons or 
owr S6 percent of the total continental phytomass (minus 
fiwfi, lakes and glaciers).* This phenomenon is not unex- 
pected since the area of the tropical zone makes up almost 
42 percent of the earth's total land area and almost half of 
this zone is vegeuted by highly productive moist tropical 
forests (Table 4). 

The boreal zone (18 percent of the global reserves) is 
second m biomass reserves followed by the subtropical 
(epproximately 14 peieent), lubbonil (approscimteiy 12 

* The same holdi for the total continental area of the entire earth 
since the phytomass reaerves of InlaiMl reieivoin (riven and lakes) 
as well as the global ocaans IN mucliloimlhaii ill Vegetation com- 
muaitict on land. 



percent), and the polar zone (leas than 1 percent), ft is note- 
worthy that the boreal, subboreil and subtropical zones 
are approximately equal in area. The differences in phyto- 
mass are primarily detennbied by the degiee to wUch the 
landscape is coveied with fomta (which is greateit for the 
boreal zone). 

WitMn each of the thermal zones, a precipitoui decrease 
occurs in total phytomass and average figures per unit area 
(bionuss) from humid to semiarid and arid bioclimatic 
regions, even though the latter may be more extensive in 
area. However, biomass values (phytomass par ueaonit) 
for humid aieas nnly (dominated by fore<!t communities) 
increases from north to south. This is a crucial (actor 
ceiponsible for the piogressive increase In the biomass esti- 
mates throughout the thermal :?ones, moving ihniiBrly 
from subboreal to subtropical zones. 

Thus, the geographic distribution of phytomass reserves 
over the earth's land is determined by the forest types of 
the different soil-vegetation formations. Indeed, the total 
phytomaBieMrvee of the world's fofestsaie 1.96X 10*' 
metric tons, i.e., almost 82 percent of the entire terrestrial 
phytomass, with the total under forest cover amounting to 



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PRODUCTIVITY OF THE WORLD'S MAIN ECOSYSTEMS 



19 



S X 10'' km' or 39 percent* of the area of the earth's sur- 
fice. Troirfcd nme fafnts nwke up half of tills totad (1 j03 

X 10" metric tons), boreal zone forests account for some 
20 percent (0.4 X 10" metric toru) and subboreal and sub- 
tropical forests an additional IS percent each. It Is signifi- 
cant that the phytomass reserves of desert types of soil- 
vegetation formatioru, which occupy a total area of 2.89 X 
1 0^ km' ^ peieeHt of the Midt*s mtfaoa) nulce up only 
0.02 X I0"inatiietoii8or0j8pefeantoftotdlaiulpliyto- 
ma<s.t 

The diitilbtttkm of oOMuUc phy toman generally follows 
the pdndplat estabHsbed for tematilal environments, and 
yet there are some differences. The concept of the marine 
ZOOatlon wu proposed by L. A. Zenkevich (1948). Under- 
lying this concept of natural oceanic sanasls a combination 
of the same five factors that influence terre5trial produc- 
tivity: light, temperature, nutrients, substrate and the inter- 
rdalionahips of organisms (Boforov, 1969). Also Importaiit 
in the geography of terrestrial and oceanic phytomass is the 
effect of vertical (for land) and abyssal (for ocean) zonality. 
Sbnikr to the land, the ocean is chaiaeteitaed by the alter* 

nation of zones high and low in phytomass fas well as in 
zoomass). The zones of land and ocean which are relatively 
ifch In Ihdng matter are characterized by the cyclonic regime 
of air and/or water circulation. Such regimes in the ocean 
cause mixing of water zones and upwelUng of nutrients to 
surfooe iriiytoplankton. in areas with an antkydank regime, 
the surface waters sink and thus deprive the upper layers of 
nutrients. The areas poor in living matter are confined to 
antkydonlc regions in tiie center of the Pacific and Atlantic 
Oceans and in the southern Indian Ocean. The areas high in 
Uving matter occupy less than a quarter of the world's 
oceans (Bogonnrerdl. 1968; Koblen^MiAkeefae. 1968). 

And yet, in contrast to the land, the highest marine accu- 
mulation of living organic matter occun at moderate tem- 
perate rather than tropical latttadea. This rssults not only 
from the cyclonic water currents and divergence, but also 
from the more inunsive mixing of water layers in temperate 
tatttudes under the bifhience of wtnter-autunut temperature 
fluctuations. Additional factors in the hi^ biomass of the 
Uttocal zone are sea-to-shore winds and nutrient inflow 
from river discliarge, abrasion effects, discharge of under- 
ground waters, etc. The low amouots of bionuss in high 
latitude and Antarctic waters are explained by the shorter 
growing season and lower water temperatures. The absolute 
phytomass reaerves in the world ocean are not high. 0.15 X 
10* metric tons of phytoplankton and 0.02 X 10' metric 
toruof phytobenthos for a total ot 0.17 X 10' metric tons. 
Urns, the phytomasB reserves on land exceed almost ISjOOO' 

* Aecofding to FAO data* Itonstid area iiioanwiMit anrflH 6onw 
40jlMOu(nO Im') Mnee FAO oonsldand only Mdrting and not poten- 
tial fomtad n«u. 

t AccdrJin^ to I AO JjIj. ;tu- dewrt :ir«as are omdinMieeXIISOriMi 
arid tteppet are partly classed with dcscrti. 



fold those in the ocean (Bogorov, 1969). The earth's total 
phytamaasOkidudhigOiMX 10* metric tons occufiim In 
rivers and lakes as calculated by WlitttakBr(1971)aimoimts 
to 2A X 10'* metric tons. 

The annual production of phytomass abo may be ex- 
pressed in dry weight per area unit by considering the areas 
of different soil-vegetation forxnatipns. These data have pre- 
vlmidy been published and plotted as schematic maps of the 
earth's terrestrial productivity (Rodin and Bazilevich, 1967; 
Bazikvich and Rodin, 1967). These data reveal the same 
pattern obt^ied in examlidng tfie distrlbiition of phyto- 
mass over the earth's land. I'lant biomass production in- 
creases sharply from the pole to the equator within humid 
cyclonic regions and just as sharply drop to a minimum in 
acid anticyclonic regions (Figure 1). Phytonuss production 
per area unit in humid regions gorws from less than 2 metric 
tons per liectare on the average in the polar zone to between 
6 and 13 metric tons per hectare in the boieal and subboreal 
zones and between 26 and 29 metric tons per hectare in 
subtropical and tropical zones. At the same tune, the annual 
fa c r ement in arid regiona foOows a difTerent pattern, in- 
creasing from 3 to 7 metric tons per hectare going from the 
subboreal to subtropic regions and droppmg sharply in the 
arid tropica to an average of 2 tons per heclan. Tlds is due 
to the wide occurrence in the arid subtropics of plant com- 
numities domiiuted by ephemera and ephemeroids yielding 
abundant phytomass. 

These geographic regularities of distribution of annual 
increment (and also phytomass reserves) correlate very well 
irifh cUmatk factors. This ootrdation is etuddated te the 
literature (Budyko. 1956; Grigoriev and Budyko, 1965; 
Budyko and Eihnova, 1968; Bazilevich, l>rozdov and Rodin, 
1968). In anodier instance Bazilevich aiid Rodin (1971) used 
the most recent data on phytomass production in conjunc- 
tion with data on the environmental factors affecting produc- 
tion, taduding (he bifltix of heat (ft. In kcal/cm' per year) 

and the degree of moistening (determined by the dryness 
factor, /i/I,r, where r is precipitation rate and/, is the 
latent heat o€ phase conversion). An increase in lieat rsaeives 
results in an especially large increase in production when 
R < 35-40 kcal/cm'/year (r^ons north of the middle- 
taiga subzone). When Jt is > 3S-40 kcal/cm' /year, moia> 
tore was the key limiting factor. The annual increment of 
zonal soil vegetation formations was the higlieet in regions 
with «< 35-40 kcal/cmVyear and R/Lr > 1 (1 .2 for 
northern taiga and 1 .5 for tundra) and not in regions witn 
R > 35-40 kcal/cmVyear and R/Lr < I (0.7 for subtropics 
and 0.5 for tropics). Hence, conclusions drawn by previous 
researchers with respect to climatic control over biotic 
production have not been entirely accurate (Figure 2). 

Thus, if heat reserves are sufficient, excess precipiution 
win tandt hi Ughar prodnetfon; even if moisture is ample, 
if heat reserves are insufficient, lower production will re- 
sult. A case in point is the production uf iloud-land ve^- 



Copy lighted material 




laterial 



phoouctivitv of the WKMurs main ecosystems 



21 




FIGURE 2 Ralation batwaan arifwiat production (plant growthi of 
■oM-Mgatation fonnationa and total radiation (A) and drynaa I 
WM. Tha m mi V HM ^ HiMMwi by I 



tstloii In ftfbtrofrtci and tropia wlfh in mnml inr.croeiit 

in excess of 90 metric tons per hectare. According to M. I. 
Budyko (1956), the flood-lands and espedally deltas of 
riven in then xmws dKwId be dmed wMi the wumeft 
and best moistened areas on land * Yet, a simple tempera- 
tiue : moisture ratio fails to account for all possible patterns 
<»f distribution of primary productivity. It it aho important 

to consider the duration of the growing season and effec- 
tive precipitation (precipitation minus surface discharge). 
A.M. RyahcUkov (1968) has proposed a hydiothennal 
pvodvetM^ potential {Kp) caiadatad ai 



Kp 



WTy 

d6R 



wliere it the average annual efTectlve precipitation (mm), 
TV is (he duration of the growing season in terms of lO-dXjf 
periods (36 lOnlay peiiodsinayeaikand/i isavexaa* 
annual radiation balance in iccal/cm . The hydrothemul 
productivity potential corrdales extrnndy wdl with bkmrni 
production (Figure 3). 

The annud total phytomass increment of the tematrlal 

* Coniideniion should ateo be given to nutrient abundance in flood- 

Unds and delci iomutions res 
Iwlance of the Undicapcs. 



a » 




HYDAOTHf DUAL IXJTENTIAL Of PHOD J<;T I V ITV looMI 



FIGURE 3 Cwitrttow h u mmn d»a hydrothanwM 




vegetation (Table 4) is put at 1 .72 X 10" metric tons (7 
percent of total phytomass reserves). The bulk of the phyto* 
mass of 1 .03 X 10" metric tons (60 percent of total 
piiytuiTiass) IS produced in the tropical zone, while the soil- 
vegeution formatloas of humid leHoM an letpomdUe for 
7.73 X 10'° metric tons or 45 percent of the total incre- 
ment of the earth's land. Second to the tropic is the sub- 
tcoiiiea]«Nie(34^X 10* ton, or 20 percent). Being 
roughly equal in area, the plant formations of the wb> 
boreal and boreal zones produce much less in organic mat- 
ter-18 X 10* ton (10 peioent) and IS X 10* ton (9 par- 
cent), respectively. The annual increment in polar regions 
is the lowest: a little more than 1 X 10' (0.8 percent). 

The same u for phytomass distribotion, there is a sharp 
decline in annual increment within each of the thermal 
zones in the direction from humid to semiarid and espe- 
cially arid reglant. Thii pattern ii the least pronounced in 
the subtropical zone and the most pronounced in the tropi- 
cal one, which is associated with the wide occurrence of 
arid types of vegetation largely dombiated by ephemere 
in the former zone and vast areas practically devoid of 
vegetation cover in the latter. The annual total increment 
of desert formationi faib to exceed 7.22 X 10* ton or 
■one 4 percent of the total land increment (the earth's 
srea under desert makes up some 22 percent). 

Making up some 39 percent in area, forests produce al- 
most half (49 percent, or M.1 X 10* ton) tfa« annual 
total land increment. 

It is also significant that, while occupying a very small 
area of tome 3 percent, the soil^vegetation formations 
of deltas and flood-lands produce over 20 X 10' ton (12 
percent) of organic matter to additionally conf'um their 
special biogeochemical diametar. 

The annua! increment to oceanic phytomass according 
to the latest samplmgs at home and abroad is put at 1 J- 



Copyrighted material 



raooucnviTv op the world's main EcosvsriMi 



23 



2.0 too per hectare or. making a total at 47-72 X 10* ton 
(Steemaim et A , 1957, quoted by Liefh, 1964-65; GmMr, 

1959;Koblenz-Miiihke eral., 1968; Whittaker, 1971). ThtB, 
the total annual increment of the world ocean exceeds 
304KX) percent of iti total phytomtn meive.* This ii aO 
too natural, since the ocean is dominated by unicellular 
plants with extremely rapid reproductive potentials. And 
yet, the annual Increment of tenettrlal conuminlties is 
three (iines greater than the world's oceans (including the 
increment of rivers and lakes which, according to Whittaker, 
1971) produce 1 X 10* metric tons/year. It is significant 
that even though the ocean covers 1 80 times the area of 
rivers and lakes, its phytomais reserves are only four times 
as large. The geographical pattern of productive and low- 
productive aquatoria is correctly described in the previous 
studies of primary production distribution over the world's 
oceans (Licih, 1964-65; Koblcnz-Mishkc er a/., 1968) 
(Figure 4). 

The data now available make it possible to estimate the 
primary production of the entire earth at 2.33 X 10" metric 
too«/year of organic raatler.with some 74 percent being 
produced by plant communities on land The scanty data 
available in the literature on phytomass reserves both on 
land and In the ocean are wromariMd in Tri>le 5. This table 
also includes data on the mass of consumers and reducers 
for the purpose of assessing the total quantity of living mat- 
tor of the entire planet. It Is obvious fiom the table that 
wide gaps between data ffom different sources still exist in 
some cases. Since phytomissdata are limited, especially 
thoae from the beaming of this century, many researdieit 
have attempted to estimate both phytomass reserves and 
total organic matur even though they based their conclik- 
akms on indirect btfonnationoonrdated only to die above* 

glOUnd parts of plants. 

The productivity data presented in Table S reject the 
once prevalent opinion that most of die living matter is 
concentrated in the ocean. Recent studies have repudiated 
this past misconception (Koblenz-Mlahke etaL,\ 968; 
Bogorovero/., 1968:Oiaon, 1970; Whittaker. 1971). 

According to our estimates,! the earth's total living mat- 
ter is equal to 2.42 X 10'^ metric tons. The living matter of 
the land thus exceeds by some 7S0 tfanes that of (he vmlft 
oceans. 

The flgures of phytomass primary production in litera- 
ture vary widely from author to author (Table 6). This is 
especially true of the estimated production on the contt 
nents. According to our calculations, production by the 
terrestrial landscape far exceeds that published by most 

• Smm 1.700 peiomt amr^ to WUnafcn (1971) aiitee lie pM 

cxxanic phytonusi leseivc* at 3 .3 x t o'; however, we relied vpoe 

a value of 0.17 X lo' ton in dealing with daU from literature, 
t I he sequence of figures for consumers and reducers ulopicd in 
this iMper i* tnied upon ttte data of Ihivigneaud and Tanghe (1968). 



Other authors witlr the exception of Deevey (1960), the 
American woilcers as quoted by Duvlgneiiid and Tanghe 

(1968), and the most recent daU of Olson (1970), Whit- 
taker (197 1) and Ueth (1972). Such largs USSumui may 
be most ratlondly cjcpMned by tiie fiKt diat 0) many 
authors have relied on sccond-tiand information and have 
extrapolated widely in estimating primary production, (ii) 
many have fafled to take notice of the considerable annual 
Increment prudnced by the underground parts of plants 
and (iii) there has been a paud^ of data of recent origin 
based upon modem analytical techniques. 

Generalizations of potential primary productivity may 
best be estimated by evaluating the ratio between annual 
increment and phytomass of the continents. To calculate 
this ratk> incorporating the data of ttioie aodiors iiilo foil 
to account for the extent phytomass reserves, it is advisable 
to use the value 2.4 X 10" metric tons which we have 
found to be the average phytomass value cited in most re- 
cent puhlications on the subject. These publications give 
ratios of increment to phytomass from 0.15 to 1 .9 percent 
with the exception of Deevey, Ueth, Whittaker, and the 
authors of this paper Yet, actual sampHng of different 
types of terrestrial vegetation shows that there are few plant 
oomnmnittesirliidi yield such low ratios. Thus, the ratio 
between annual increment and phytomass reserves for 
tundra is between 10 and 20 percent, for boreal and sub- 
boreal fmests 2 to 5 percent, for subtropical forests 5 to 6 
percent, for tropical forests 8 to 10 percent, for the grass 
communities of steppes, prairies and savaimas 20 to 55 per- 
cent, for dsaert oomnnnilles 90 to 75 peieent, and for 
conununities of annual field aops it is 100 percent (Rodin 
and Bazilevich, 1967). Thus, the absolute value of 1 .09 to 
1.72X 10" metric tons and die relative (6 to 7 percent) 
values for armual increase in phytomass on land seem to 
be consisteot virith those of Whittaker (1971). 

Eattanates of the ammal increments and reserves of land 
phytomass currently under discussion have been based on 
actual determinations. The patterns of distribution of 
Hving pfamt organic matter were ealaMlshed by a detailed 
calculation of the areas occupied by various soil vegetation 
formations. This approach enabled us to calculate with 
greate r precision the phytomass reserves and the relatloii- 
ships with the annual increment for the land. These results 
have been compared with our calculations of the cone- 
sponding values for the vrarid*a oceans, ivhldi fltustntes 
the role of mineral nutrition in primary productivity. 
Phytomass production has been shown to be highest in the 
zone in which physiographic processes are most intensive 
due to a favorable combination ot v. arnUh and moisture, 
such as the tropical zone. Geographical regularities of 
phytomass distribution per unit area (= biomass) for basic 
types of the earth's vegetation (Rodin and Bazilevich. 
1967; Bazilevich and Rodin, 1967) indicate that soil- 
vegetation with both high and low values are characteristic 



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Copyrighted material 



PRODUCTIVITY OF THE WORLD'S MAIN ECOSYSTEMS 

TABLE 6 Primary Production (10^ nwtrie torn ■ yar, dry «wight) 



OmUMato Oenu Totd 



Amfcart 




ViHomtof 
nntMata 




ItactBtof 
flwtltei 


fkodocliM 


fmeoMof 
ftart Han 


SchrL>doi, 1919* 


M.2 


u 










Ereny, 192(^ 




u 














Nodd«k. 1937« 




lA 


113 


59.000 


14«J 


6.1 


IUI^,19«4 


_ 


_ 


176-815 


95^00^254100 


_ 


_ 


SumimmettA, 1187 


— 




60 


314)00 


_ 




FoM. I9S8 




1.9 


128 


66.700 


174 


7J 


Gcuner, 1959 


— 


— 


47-60 


25.000-31.000 


_ 


_ 


Mulkr. 1960 


22.8 


0.9 










Decvcy. 1960 


182.0 


7.6 


— 




— 


— 


Duvi|'nc;ni(), 1 962 


34J 


14 


— 


— 


_ 


— 


Ueth, 1964-65 


464 


1.9 


— 


— 


— 


— 


IJBlk,l»72 


100^ 


4.2 


55 


354)00 


155.2 




MMMOO.IMS' 


IM 


a? 


- 


- 


- 


- 


DuT^neind nd Thngue, 19SI 


S3.0 


2.2 


30 


17,600 


83 




Nichiporovich, 1968 


S0.0 


24) 


50 


294)00 


100 


74 


Bykhovski uid Bannikov, 1968 










92 


3J 


KoblcntvMuhkerra/.. I96B 






60-72 


35.290 






aulhon (cited by 














Omipieaud and l^miM. 1968) 










70*280 


2.9-llJ 


■iVinv.1969 






55 


32J50 








15-53(16) 


0.15^J 










WhitUker, 1971 


1094) 




55 


1,666 


164 


SJ 


Ouj own data, 1970 


17M 




60^ 


35.290 


232.S 


9j6 



'Ciled by Licth. 1964-6$. 
^iled by Veroadikj, 1934. 
^Taken from Kobtenta-Mbhke. 1968. 



of every thenrnl belt. ThU is expl^Md by a nonuniform 
latitudinal distribution of energy resources, difTerent con- 
ditions of moistiue ntppty, and by the gamtic propertka 
of prlnuiry produoeit. 

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576-588. 

BnUevidi, N. 1.. A. V. Drozdov, and L. E. Rodin. 1968. Produc- 
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261-271. 

BizDevlch. N. I., and L. 6. Kodfn. 1967. Maps of productivity and 

the biologKal L>\;lc in the earth's pnn^ipjl ■.er:cstnjl vctietjtion 
typci, Ifvcstiya (ici^ji.raphichciifcoKo ()hJiv;hcsr.a, Lcrungiad 
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BmOevkh, N. I., and L. b. Rodin. 197 1 . Productivity and the ciicu- 
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BazUevkh. N. 1., L. E. Rodin, and N. N. Roooir. 1971. Goocraphiod 
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Bornov. V. G. 1969. Ufli of Om Ocaau. Znanlye. Biology Setta. 

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Budyko, M. I., and N. A. Yeflmova. 196S. The use of solar energy 

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ductivity of forest ecosystems Prof BiuwU Symp., 27-31 

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M. J. Duever. 1969. The structure of tropical foieala io fkliana 

awl Oolumbia. Bioadanoe 19(8):693-696. 



26 



Giimj«r. A. A^aiid U. L Bodyko. 19S6. Tin pwkidicitr lawof 
geognpUe uniUty. Doktady Akad. Nnk» USSR 1I0(1):139^ 
1)2. 

Grijoijev, A. A , and M 1 Hudyko I')fi5 The relationship bctwtM 
heal and wa(cr balances and the intensity of geographical piO> 
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Jcnik, J. 1971. Root •tnicnti* and uadnsiound Woniau la mfttf 
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1969. UNESCO. 

Kin, T., and H ()^>..w.i 1971. Assessment of primao" pr >.iuction 
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27-31 October 1969. UNESCO. 

KoUsB4IUdBe, O. I., V. V. VolkowiniU, and Yu. G. Katamnn. 
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Kovda. V. A !%9, Tlu' prnblLTti vit" binK>:n jl jnd econoiiiu- produc- 

livitv ol ihe L-aith'sljnd aiL-as, p. 8-24. Ar Basic problems oi 

biolo^cal productivity. Nuuka, Ixrningrad. (Translated in Soviet 

Geography , January 1971). 
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gnyliliciiei Tudwabvcb. Wiabaden, Frank Sleiner. p. 72-80. 
Ueth, H. 1972. Constniction de la productivite primaire du globe. 

Nature et Resources, UNFSCO, Pans 8(2) 6-11. 
Molchanov, A. A. 1964. ScicntiTic fundamentals of farming in the 

oak groves of the wooded steppe. Naulca. Moscow. 255 p. 
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phyiiologie. Berilii 12(2):934-1254. 
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lioii Oil Aft atrdk ZNanieu BloL Scr., IfoMow 12:2»48. 



OImm, J. S. 1970. GeoBraphie index of voiM ecoeyttema. p. 297- 

304. In D. E. Rcichle (ed.) Analysis of tcmpcraic lorcit eco- 
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Vzairoootnoiheniya lesa i bolota. Nauka, Moscow. 

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Variidk MGU, Googr.. Moaooir 5:41-4S. 

8endi«o«i.&l|.(«d.)1964 PhysicotMgnpfelalAdMoriltt 
World. USSR Acad. ScL (Legend tranabted hi Soviet Geog- 
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Soil rcgmies and proceises. 1970. Transactions of Estonian Agri* 
cultural Academy, 65, Tartu. 342 p. 

Steemann, N., and E. A. Jenaea. 1957. Primary oceanic productioo. 
Hie autotrophic pfodnctkm of oiganic Batter in the ocnBB. ScL 
RepL Oanlih De«ip4ea E«p«d.. 195042. GalaliiM Rept. 1:49- 
I3S. 

Titiyanova. A. A. 1967. Uctamoii A* MovliMi. NowoiMnk 

Um». 131 p. 

Vemadski. V. I. 1926. Biosfera. Leningrad. 146 p. 

Vernadski, V I. 1934. Essays in Geochemistry. Russian edition. 

Leningrad. 224 p. 
Vemadaki. V. 1. 1940. BiogeocfaeBical Eaaeya. Mnirnir I rniiynil 

WrfMriM, R. B. 197 1 . Communities and eooviMi. Thlid VMnl^ 

big. Macmillan Company, New York. ISO p. 
Zenkcvich, 1.. A. 1948. The biological stiuclne of iWoeina.£ooL 

Joum., Leniitgrad 27(2): 113-124. 



Copyriyliicu liiaiorial 



PRODUCTIVITY OF 
MARINE ECOSYSTEMS 



M. J. DUNBAR 



AHTtMCT 

The prejcnt knowled^ic ol the levels al hiological pruductu>n in llie 
world ocean li briefly revtewed, togcihet with a discuubn of vaiia- 
tion bl ecosystem patterns with reference to the evolution of til* 
qriMnt in diffewnl nuiiae cUmates. Emphaik is pnn to (1) MMinr 
MQVtr and til* tntnpoMnt of mun witlilit tiw prodvction ty»- 
tenu; (2) nutrienl lupply aitd nutrient capital: (3) metaMic Hfu- 
lation with respect to temperature: and (4) the importance of 
s<.-a?<)rulity in the building! up of t<imineri.iallv ; vpli iir ilili natural 
stocks. Recent Ctanadian work on the cticcls ot treiihwoter run ott 
on marine productivity is discussed, and attention is drawn to the 
uttA foT mofc inlcnavc study of climatic cydca and tlicir effect 
la cMHtagfaapipMc Mht in mxiimim praductioa aoim 



INTRODUCTION 

The bMogieal prodtictfvity of the KM b of very great prac- 

tical significance to man. As a consequence, the literature 
on this subject has been growing logarithmically for a cen- 
tury. wHh many notable tummartet in book fomt. In tplte 
of tliis it is unfortunately still true [.nul I (jUDle here from 
Riley (1972)] that '*vt still know veiy Uttle about marine 
prodactWity.** The ht^r trophic tevelt. particularly thoae 
of commercial interest, are better known and easier to mea- 
sure than producer trophic levels, in fact, the relative rich- 
ness of different parts of tlie world oceans can be measured 
by sustained commercial taJce as well ai, or better than, in 
terms of primary production. 

Presenting a coherent general account of our present 
lOKMlMgBOf marine productkmii therefore not simple. 
If is unnecessarily rendered even more difficult by the lack 
ot standardization of terms and units, a matter that editors 

27 



of the IIP Synthesis VoliunM diould vigorously address. 

"There are several different ways of measurinp '"r fixation, 
and at least three other techniques of investigating primary 
production" (Riley, 1972). Secondary production ta iar 
more difficult to iTieasiire, as was emphasized most recently 
at the IBP/PM WorkmgConterence in Rome last year. No 
fflBtheniatieal genhtt it fequtacd to cotwert nrilUgnuna to 

grams, or even saturation values of oxygen concentration 
to millihters per liter, but to convert milligrams of carbon 
fixation per tquare meter per day to mflllpanii per cubic 
meter per year is iinpossihie without other information 
which is often not supphed. Biomass values expressed in 
units per volume or per area per day give totally diflierent 
sorts of infortnathN) from those coav^ed by average values 
per year, etc. 

EOOSYtTEM niOCESSES 

For a scholarfy review of our understanding of marine eco- 
system processes, and for detailed comparison of the Sar- 
gaaw Sea, the Eastern Tropical Atlantic, and Long Island 
Sound, at examples of marine areas, I refer you to Riley 
(1972). AUhou^ this paper emphasizes interrelations be* 
tween elements within the ecosystem rather than compan- 
ions of ecosystems, it is particularly valuable for its insightt 
into production processes. I wOl begui here by meirtioniog 
tome of Riley't points: 

1 . The total range of productivity in marine eooqritems 

is about the same as that of terreslri;il ecosystems. 

2. Apart from extremes ol production, the richest areas 



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28 



M.AOUfliaAR 



of the tea are only some three to five times at productive as 
the poorest areas. The extremes of the productivity ipectniin 
are fapceieatad by coral reefs and Uulassitt commuaitias on 
the one hand and the Antic Ooaan on the other; total annual 

production per unit area in the Arctic Ooeanislais than 

one day's production on a coral reef. 

3. Primary production is channeled into different 
secondary and tertiary trophic levels in different re^ons, 
i.e., tov/ard production of large carnivores (whales or fishes - 
and it should be noted that there appears to be an ecological 
choice within the carnivore group) or bacteria and dettitus 
feeders or herbivores. 

4. Open ocean ecosystems are most nearly analogous to 
grassland communities. Both systems are of intermediate 
productivTly: rates of production are higli but the plant com- 
munity IS small in terms ul total biomass due to constant 
cropping by consumer*. Both ecosystems support a diversl- 
ficd system of herbivores and carnivores. The grassland eco- 
system produces a residuum of humus which is worked 
over by sod fauna and flora. The otarfaie equivalent is a 
residuum of particulate snd dissolved organic matter in the 
water column and in bottom sediments. Organic detritus 

is two orders of magnitude largar than that of tlw Uving 
biomass; and its accumulation obviously is due to its refrac- 
tory nature, yet, in time it is utilized and contributes to 
ecoqrsteni ppoducthd^, as eiMmced hy the ralathnly 
small organic content that is left hi deep sea sediments 
(RUey, 1972). 

5. Estimates for net primary production m difTerant 
latitudes n) the world ocean are in mgC/m'/day; Gulf of 
Guinea. 365 gC/m'/year; lu>ng Island Sound. 190 gC/mV 
year: Sargasso &a, 70 to 145 gC/m'/year. Tlie normal 
range of oceanic primary' production is estimated by Riley 
(1970) to be between 50 and 150 gC/m'/year (150 to 300 g 
dry weight/m'/year) which allows for seasonal variation. 
Production in inshore areas and areas of upweiling can be 
much hlghn, up to ten times greater than tiiese oceanic 
values. 

These observations stimulate three conunents. First, 
coral reefs are no longer officially included among the 
themes uiuler IBP/PM study . which is a pity; they are 
oases of extremely high production in oceanic tropical 
deserts, or near-deserts, and as such pose unresolved ques- 
tions OB the mechanisms by wtiich the essential nutrient 
capita! is retained and recycled by biota. Secondly, turtle 
grass ( fhalassia) beds are similar localized areas of high 
production In tropical oceans, and Patriquin ( 197 1 ) has 
shown that "nitrogen for the growth of Thatassta is de- 
rived exclusively from gaseous nitrogen fixed by anaerobic 
bacteria te the rMzoaphere. It had pravtoudy bom unsua* 
pected that such a phenomenon might be important in (he 
ecology of aquatic plants." This is an important discovery 
and doubdMB a raijor sthnulant for further raseaidi. 



Thirdly, the differences m the end products of the food 
chains are crucial and have received little attention by 
marine eoologists even as late as the food chain sympooaiun 
in Denmark in 1968. Why large whales as opposed to large 

fishes r iicrbivorc , lis opposed to detritus eaters form the 
final or dominant link in the food chain in different areas 
may well be explained by environmental differences. For 
example, the depth of the euphotic zone in the SarfSHO 
Sea causes a thin dispersion of food and hence discourages 
the development of predator populations. Selection of the 
final link may, however, also have much to do with evolu- 
tionary chance or with the particular advantages or disad- 
vantages of different body organizations and metabolic 
systems under different environmental conditions. Resolu- 
tion of these questions could explain tor instance why 
there are no large exploitable tish populations in Antarctic 
watefs. These evdulionaiy aapeeti of marine eoosystem 
produethdty form part of my coooems hi this paper. 

ECOSYSTEM PRODUCTION 

One recent pubUcation comparmg productivity of different 
parts of the sea is the oollectloa entitled Fertility of the See 
fCostlow. 1971 ), which places some emphasis on the im- 
portance of organic substances in the development of marine 
plant populations, both planktonic and bentfiic. Althou^ 

pioneer work on external metabolites and their ecological 
significance dales back at least to 1947 (Lucas, 1947), we 
still tend to think only bi termsofbiorgiuiic nutrients when 

consideiing primary production Provasoli (1963) discussed 
the organic r^ulation of phytoplankton fertility, Pralush 
(1971) summarized the importance of terrigenous organic 
matter in coastal primary production-particularly the part 
that low molecular weight fractions of humic matter appar- 
ently play. Prakash (1971) differentiales sharply between 
coastal waters and open ocean as being two distinct environ- 
ments* not only in terms of production itself, but also in 
terms of diemical constituents (especially the role of humic 
substances in the COestal zone). Although the marine section 
of IBP has been concerned mainly with coastal waters, the 
organic enrichment of coastal water has not received much 
attention. 

IBP research has made clear the importance of forms of 
primary production other than the purely phytoplanktonic. 
Canadian work in St. Margaret's Bay, Nova Scotia, has iliomi 
that the annua! seaweed production in coastal enclosed 
waters can be three times as large as the primary planktonic 
produetlon. Similar results have appeared in IBP studies in 
the Philippines and in Japan, and work in the Japanese, 
Romanian, Netherlands, and South African IBP programs 
hu demonstrated the high production of microfrfiytobenthoe 

in shallow water. Much of this research is only now begin- 
ning to reach the open hterature. Rather than attempting 
a cBview of tiie eottae iBP/PM reaaafdi on prodttcthd^ 1 



Copyrighted material 



PBOfKICTIVITY OF MARINE ECOSYSTEMS 



29 



shall consider the general aspects of marine productivity 
and, in paitieuhr, the pitlentt of •ooaytteai cycUng foudd 

in the sea. This is best introduced with some of the prindplM 
e«ential for modeUng the marine production cycle. 

ENERGY SUPPLY (LIGHT AND HEAT) PROM THE SUN 
I wish I htd the coursge or the bradiness of physicists tnd 

engineers, who claim to know what energ\ is Most biologists 
make no such claim. What energy does is simpler to under* 
staml, tmt I think that whtn mgineen, and perhaps lomt 
of the physicists, too, talk of energy they really mean dtf« 
ference in energy level, which is quite a different thing. 
Energy, on its way through the Mosystem, becomes Inoor- 
porated into various fonns of organic matter for varying 
periods of time. This is not textbook ecology, but the best 
description of how an ecosystem, or an iadMdita], functfcms. 
Whatever eneigf it, matter la one of its forms, and it is time 
ecological theory cinia to tenna with caiiy twentietli* 
century physics. 

NUTRIENT SUPPLY AND NUTRIENT CAPITAL 

If a word other than "energy" is required here, let us coin 
something like "biopotential" for the nutrients without 
which production is not possible. The availability of 
nutrients it probably the limiting factor in most marine 
systems, e p , althouph the polar winter obviously renders 
photosynthesis impossible, there is an abundance of light 
in the polar rannmer, and it is not rfiortage of light that 
renders the Arctic Ocean so low In productivity, but the 
scarcity of nutrients in the euj^otic zone-a result of 
intense vertica] density itiatificatlon. 

TiMPERATURC 

l ife has .idapted to the physical variables of the environ- 
ment, both in the course of evolution time and in the func* 
tional dynamics of the system, so that environmental 

temperature becomes a basic variable uf the system to 
which organic responses are made at both the proximate 
and the idtfanate levels. Regulation of the retetion between 
temperature and metabolic rate is normal, so that in 
colder environments the temperature-metabolism curve 
is simply shifted to the left, toward the lower temperatine 
end of the horizontal a.xis. TTiis has an obvious selective 
advantage; in fact, according to the Qio relationships ex- 
trapolated fitom temperate climates, life for poikOotherms 
would be impossible in Arctic and Antarctic seas; but there 
is plenty of life in both. Growth rates, also, can be compen- 
sated at low temperatures if the evolutionary (adaptive) 
advantage is necessary for silfVival— as in the larval slagH of 
certain invertebrates (for a summary of these phenomena, 
see Dunbar, 1968). Temperatuie, liierefore, becomes in 



ecological theory a less Umitmg variable than it was formerly 
thougHttobe. 

VERTICAL STABILITY OF THE WATER COLUMN 

The supply of nutrients to the euphotic upper layer is en- 
tirely dependent upon instability of the water column, 
except wheie direct outflow of mitrients Irom the land 
is concerned, which is usually a local effect. Analysis of 
the world map of marine production will show that it is 
this fiKtor of vertical inMabllity, and not temperature or 
latitude Oight), which controls the pattern of productivity. 
Instability in the water column Is achieved in various ways: 
upwelUng caused by wind or Corlolis, or both; vertical 
exchange in vrinter in temperate and subarctic regions; 
mixing of water masses; storm turbulence: tidal ndxint. 

SEASONALITY 

The gradient between the weak seasonality of the tropica 
and the extreme winter-summer oscillation of polar regiooi 
has not been fully recognized, probably because its im- 
portance depends far less upon temperature than upon the 
cycling of nutrients and of plant materials which form the 
food supply for the secondary producers. Where winter 
dictates a seasonal pause (a very long pause indeed in high 
northern laHtudee) in primary production, the life cydei 
of the secondary producers are long. The lifetime of the 
larger copepods in the Arctic and much of the subarctic 
is ofw year at least, sometimes two or even three yean. The 
one-year minimum has most probably evolved not as a 
Mcessary response to low temperature but in response to 
tlie need for detayhrg spawning periods until the next Moom 

of the phytoplankton assures a food supply for the next 
generation. This is tlie basic reason for the high standing 
crops of xooplankton hi tenqtentum and subpolar waters 
and, conversely, for the low standing crops in the stable 
tropics. The high standing aops in mid-latitudes have much 
to do widi the support of commercially exploitBHa ilOGlEa 
at the tertiary or Mifier food chain la«ils,U.,fldi and 
manunals. 

The effect of this seasonality is thus to cause energy 

storage in the system, to delay the flow of energy through 
it. This is to the economic advantags of mankind, for it is 
largely the lack of this Storage factor bi the stable tropics 
that renders those regions so poor in exploitable populationi, 
together with the low nutrient capital and the deep eu- 
photic zone. Where upwelling occun in tropkal btlludes. 
on the other hand, bringing a constant and large supply of 
nutrients into the system, high standing crops of zooplank- 
ton and of higher trophic levels become possible; energy 
is caught in its rapid flight and stored in exploitable stocks. 

Seasonality thus controls to a large extent the type of 
cycling in the system. In mid and high latitudes the phyto- 



Copy righted material 



30 



plankton blooms, whkh ire seasonal, support 1onf4ived 

200plankton which carry the populations thnnifji to the 
next lune of phytopbinktun production. In the stable tropics 
the lack of seasonality, coufried with low nutrient capital, 
results in rapid use of both nutrients and phytoplankton as 
they become avallaUa. The cycling is rapid and the standing 
crops are low. This has been supposed to result in constant 
concentrations mF |ii ;niary and secondary producen,but 
recent work, for instance tliat of Steven and Glombitza 
( 1 972) in Barbados waters, has shown that there can be 
well-marked oscillations in both. 

There is much still to be done on these planktonic cycles. 
T. R. Parsons pointed out at the Rome Working Conference 
(1971) that different types of plankton cycles are found 
even in different regions where the general conditions 
nii(^t be considered to be much the same on Tirst exami- 
nation. The classic pattern based on work in the North Sea 
shows a major peak of zooplanklon following the spring 
phytoplankton bloom and a minor zooplankton peak fol- 
lowing an autumnal bloom. In the North Flacific it seems 
that tlie /oopiankton peak occurs in summer at tlu» sflme 
limc as the maximum ot phytoplankton production, and 
the phytoplankton peak is far less steep. These differences 
may involve differences in the food-chains and in physical 
conditions such as the behaviour of the tliermoclinc and 
the critical depth. 

The Rome IBP Conference in 1971, in fact, recommended 
detailed study of these differences using dau already avail- 
able. Associated wMi flieae phenomena Is the sucoeoional 
dominance cif planktonic species, a pattern which also differs 
from region to region. Voronina (1970) drew attention to 
the seasonal cycles of three common copepod species in the 
Antarctic: "Different tirnine In the summer biomass maxi- 
mum in these copepods provides a mechanism leading to tlie 
spatial isolation of their maxima. As a rule the maximum 

biomass o\' Cjlatii'iJcs acmu^ is developed in a nioic suulli 
em position from that of Calanus propinquus or in a deeper 
layer, while RMnedama glgu has the norfliemmost maidnia. 
In the Antarctic convergence zone, where there is a me- 
chanical concentration of plankton, the prevailing species 
aiMeaad oat aaodwr in the snne order. The bkjloglial im> 
ponaacci of aU these relationships is obvious. The sequence 
in appearance in the plankton of the numerous herbivorous 
species increases the intensive grazing period and the degree 
of phytoplankton utilization. The spatial differences in the 
maxima of different species decrease the competition be- 
tween them." Again, the importance of evolutionary con- 
siderations in tiie study of present day marine production 
is illustrated. The production : biomass ratio is, of course, 
intimately involved in all these cyclical patterns. Several 
widely dispersed IBP projects have been engaged in the study 
of production " biomass ralios. and l!ioit syntliesis and com- 
parison will constitute an important advance. Perhaps we 
should Intiodiica a new concept of "production per qrcle 



per square meter," in addition to production ratoa per unit 

time. Low production per cycle would mean a low ftUlding 
crop and a high production : biomass ratio. 

FRESHWATER RUNOFF FROIN THE UUliO 

In estuarine and enclosed coastal regions freshwater runolT 

is often vitally important in establishing and maintaining 
fertility by virtue of the entraining effect, which brings 
water from deeper layers to the surface. Thb is well known 
in eastern Canada; for example, in the Gulf of St. Lawrence. 
Sutcliffe (1972) has recently shown that annual variatioiu 
in the land drainage inflow to the Golf of St. Lawrence can 
be correlated positively with the commercial catches of 
several species of fuh and faivertebrates. There is a time l«g 
appropriate for each species. namely the mmiber of yeara 
between spawning and recruitment into the commercial 
stock. It may not b« generally recognized, however, that 
hydroelectric development in many parts of the world has 
altered the seasonal balance of the runoff profoundly, and 
thai this must have serious effects on productivity. It is the 
high nalutal spiing runolT titat is important here. Hans Neu, 
of the Bedford Institute of Oceanography (personal com* 
nninicatiunK cs'.imates that the natural ratio of spring to 
autumn mllow at the beginning ot this century into the Gulf 
of St. Lawrence was approximately 3:1. The present ratio, 
following hydroelectric development and the holding back 
of the spring inflow, is 1.6 : 1. The "ideal" ratio conceived 
by the power company would be I : I. Here is an obvious 
contlicf of legitimate commercial interests and ecological 
principles which must somehow be adjusted. 

SUMMARY 

I have put some emphasis on the evolutionary aspects of 

the study of marine productivity; a more detailed discussioil 
would require more space than is available here. But it 
is important to mention fhe tanpermanence of particular 
geographic patterns in marine production. Nothing is so 
certain as change itself. Marine (or hydrospheric» subsurface) 
cifanatea. Hke tte atnraapherie dimaicswithwbkdilliqf we 
linked, change cyclically with various periodicities and am- 
plitudes. Shice the pattern of marine prodiKtivity is in part 
climatically determined, the pattern must be expected to 
vary. For example, paleoclimatic studies invdving deep-sea 
cores make clear that the productivity of surface waters is 
quite changeable over a long time scale. The history of the 
last century, moreover, shows that marine dimates are also 
changeable in large amplitude over a much smaller time scale 
as well. The shift in the cod and halibut fisheries in the 
North Atlantic and subarctic serves as an impressive exam- 
ple. The growth of sea-going salmon fisheries in West Green- 
land and northern Norway during the past 10 years also 
may be related to dimatie ehaofB. 



Copyrighted material 



raoDuenvrrv op MAfHNff weetiwnm 



31 



It is probably within our power to predict sucli roaiine 
climatic changes, if we mobilize oar lAtmuttioml leMWCW 
to attack the problem. The changes are of immense eco- 
nomic signiflcance. The international coordination of scien- 
tific resources toward specific ends has been a conoem of 
both IG Y and IBP; and their coordination has been a suc- 
cess. The problems of prediction of hydrospheric climatic 
change offer a great opportuniQr for the geophysicists and 
the biologists to pool their ceaourcesand their dUlis. 



REFERENCES 

Oocliow. J. D. (cd.) 1971. Fettiiily of die an. Goidon and BrMdi 

Science Publishers, New York, London, Paris. 2 volumes. 
Dunbai, M. J. I%8. Ecological development in polar regions. 

Prentice-Hall. Englewood CUfU. N J 1 19 p. 
Lucas, C. t. 1947. The ecological effects of external metabolite*. 

Biol, Rev. 20:270-295. 
fkUiquiii, D. G. 1971. The otigin of nitrasm and pbiopbonii for 



growdi of the marine Mgioiperfli Thakala Uttudbwm Konig. 
HS. Ibeiis. McCni Univ. 193 p. 
firakaA, A. 1971. Terrigenous organic matter and coastal phyio- 

planklon fertility, p. .151-368. In I D. CimIuw (ctl.) fertility 
of the Sea. Vol. 2. Goidon and Brcicli Science PubliUicrs, New 
York. London, Paris, 
ftovasoli. L. 1963. Oi|aiuc refutation of phyiopUnkton fertility, 
p. 16S-219. At M. N. UB («d.) Tin Sea. Vol 1 tnlemieiwe. 
Loatdon. 

Riley. G. A. 1970. ftetlciilate oipnie matier in aei water, p. l-I It. 

In Russell and Yongc (cd ) Adv. Mar. Biol. 8. 
Riley. G. A. 1972. Paiiernt uf production in marine ecosystems, 
p. 91-1 12. In 1. A wjcn«(ed.>EcoaysleinStnMuieaiidFM«etlaa. 

Oregon Slate Univ. Press. 
Steven, D. M., and R. Glombitza. 1972. Oscillating variations of a 
phy toptankton population in a liopicsl ocean. Natitte 237(S3SO): 
lOS-107. 

SutclilTc, W. H.. Jr. 1972. Sonte relations of tand drainafe, mitrienla, 
particulate material, and Tish catch in two eastern Canadbn bays. 

J I ish Res. BJ. Can. 29:357-362. 
Voromna. N.M.I 970. Seasonal cycles of some common Antarctic 
copepoJ HH-cics. p. 162-172. In M. W. Holdgaie (ed.) Anurctic 
Ccialasy. VoL 1. Acadcinic Pieu. London. New York. 604 p. 



Copyrighted material 



AN ANALYSIS OF 
FACTORS GOVERNING 
PRODUCTIVITY IN LAKES 
AND RESERVOIRS' 



M. BRYLINSKY and K. H. MANN 



ABSTRACT 

Data collectcti ns part of ihc International Bio- 
logical Program from 43 lakes and 1 2 reservoirs, 
distributed from the tropics to tlie Arctic, were 
sut»jected to statistical analysis to establish which 
factors are important in controlling production ami 
how they are related, in the whole body ot data, 
variables related to solar energy input liave a 



greater influence on production than variables 
related to nutrient concentration: in lakes within a 
narrow range of latitude, nutrient-related variables 
assume greater importance. Morphological factors 
have little influence on productivity per unit area 
in either case. Chloropiiyll a concentration is a 
sood indicator of nutrient conditions and when 
combined with an energy-related variable consti- 
tutes a good estimator of primary production. 



• IMi pifOT b piMiihMl b M in the Jamitty 1973 IM or Uow^^ 

32 



Cop yrigh ted materiali 



PRODUCTIVITY OF 
FOREST ECOSYSTEMS* 



JERRY S. OLSON 



INTRODUCTION 

This paper is but one step toward IBP's synthesis of under- 
standing the biological basis of productivity and human 
welftre. My primary objective Is to asaesa nujor cotnpmiMiti 
of total pruduction estimates for wooded ecosystenu: 
forests and other stands typifled by numerous, usually 
large, more or less long-lived trees. The Terrestrial Produc- 
tivity (PT ) Woodlands Working Group's workshop held bl 
Oak Ridge, August 13-26. 1972, served to highlight progress 
and problems, but its numerous data and interpretatiunii 
will emerge mainly in later synthesis.^ Workshops of IBP/PT 
Grassland and Tundra Working Groups, and on Arid Lands 
and Wetlands research (being mtegrated elsewhere), each 
have their own themes on major bknoe types of the vrarld. 
All these five groups are expected to contribute to the PT 
Section theme 6: "Analysis of Ecosystems." Yet the eco- 
system analysis theme has had no working group, and only 
informal mmies of working between other groups. 

Two working hypotheses are that woodlands have (i) a 
pradomlnant part of dtt iiiiioift Uocpbeie'ls 
tnd protebly alio (ii) a higher bkdogical production than 

• Research supported by thf rj^icrr, Divid.n js Forest Biom*. US- 
lilt' (Contribution Nu, 148). funded by the National Science I oun- 
dation under Interagency Agreement AG-199. 4U-I93-69. and by 
the Oak Ridge National Labotatoiy. which it operated by the Union 
Carbide Corpontion niidsr rantiact for lU. Atonic fmtg/ 
Commission. 

^ Reports and data banks brought to that workshop or deveioped 
during it have been uilLitcd lor participant editing by Rcicble t f 
of (1973c). 1 (hank those participants and many authors cited in 
my bibliography for contributing to a global pcnpectivc thatCOUM 
hardly have been tcatible without IBP. 

33 



other biomes A fecund objective of this chapter and some 
others (especially Rodfai et al., pp. 1 3-26) is therefore to 
marshal tabular estimates comparing terrestrial biome re- 
gions. In brief, both hypotheses seem amply conHnned by 
my leview and by rehted summaries (of. (Maon. 1970a, 
1974; Whittaker and likens, 1973; Reiners ei al , 1973). 

Present data on mass and production per unit area and 
on biome areas are obviously preliminary and will need 
improvement after IBP. Further contributions also will be 
needed for a longer term goal; the integration of knowledge 
about the main terrestrial ecosystems with that of the 
freshwater and marine systems (PF and PM sections) into 
a better global perspective. We can settle for no smaller 
scale than the whole Earth in treating problems like ihe 
bioipheie's carbon exchange with the atmosphere (cf. 
CMson. 1970a, Olson rr j/ . 1970; Whittakcf and Woodwell, 
1971 ; Whittaker and Ukcns. 1973). 

BACKGROUND 

To review the ecosystem-oriented research on forests even 

briefly would have been an impossibly large task except 
tat three circumstances. First, Ovington's (.1962, 196S) re- 
viiwi,* many wrvqrt of Rodin and Basilevidi (pp. 13-26) 

* Mr. R. G. Fontaine of the l-orestry Departnmit of the Food and 
Agricultiife Oiganiiatioa of Uie United Natioas auaeited ilut Qvii^ 
Ion's paiwr on tiopical ftnesis be |if«miled by tide at the World 
Woodlands Weikdiop at Oak Ridge. Copiei are available from fao, 
Via della Tenne di Caracella, Rome, which commisiioned Ovington's 
study My ii il presentation was to have been restricted to temper- 
ate (atvd boreal) luicsts, but a (cw comparisons with Uopical systems 
(we also Gulley.pp. 106-llS) and Other MoaMSwDI be noted fot 
comparitons. 



Copyrighted material 



34 



JilMVB.OUaN 



and symposia edited by Young (1968, 1971), Reichle 
(1970), Diivipneaud (1971), Andersson (!«7:). und Wood- 
well and Pecan (1973) provide many results and rclcrcnces 
wMeh can be oonauUed for detafls. Second, many specific 
newer contributions of the IBP are to be preKnted later in 
this symposium (Harris el al., pp. 1 16-122; GoUey, pp. 106- 
1 1 S). Third, moddliig reMarali now ptovidei an iinproving 

dynamic framework to help sharpen our focus on hnrh 
similarities and the differences among ecosystems uf con- 
trasting types and regions. 

Models arc simplified for particular purposes and local 
conditions and often need improvement. One direction of 
impfovement can Iw better injection of basic Icnowledge 
into practical models that are still oriented mainly for pro- 
fessional applications (e.g., forestry, wildlife, grazing). 
Another improvement would be for models of ecosystem 
structure and function to anticipate whole classes of 
management questions that might arise without restriction 
to conventional mad hoc modeh. In improving manage- 
ment of our resources, modeling cannot serve all roles or 
purposes at every stage, although the most interesting 
models will be those having values that reach beyond the 
spee(fic objectives of any particular modeling exercise. 
The present object and tiiat of Reichle et al. (1973c) is 
toward descriptive models: summarizing pool sizes and 
rates of income and loaa. 

PRIIMARY PRODUCTIVITY 

Some terms in the ecosystem's production budget are inher- 
ently more difficult than others to measure or derive with 
confidence. Using gn exdnqge methods to estimate gross 
primiiy piodiiction, where 

Grots primaqr pndeclioii (OPT) * Gtoai pboiosyntheiit ~ 
Surplus prodeclion (Sn -•- lt«i|lintion^n pimt pvti «) 

involves difficulties hi controlling temperature, ventilation, 
iil^t and appropriate carbon dioxide levels in the chamber 
of measurement (cuvette). Controlling conditions approxi- 
mating those sensed outside the cuvette in natural canopies 
liave l>een improved during IBP (Walker, pp. 60-63). Yet 
the extension o!' results measured al a few selected heights 
to tlie natural canopy strata poses several questions: How 
well can quiclc leaf responses be related to the sunfleck pat* 
tern of (i) truly direct sunbeams; (ii) more or less diffused 
and fluttering flecks; and (iii) the "gieen" light transmitted 
through the leaves? Do changes in the aerodynamic bound- 
ary layers around individual leaves as well as sunlit or 
shaded layers (or sides) of tree crowns distort the interpre- 
tation of what takes place in a whole stratum or canopy 
from measurements of individual leaves ' For day? of dif- 
fering weather type, how well can the hourly patterns of 
stomatal (^ning, tniupintion and pbotoiv"theais be re- 
lated to the cumulitlve Input of pihotoaynthate to the-gnen 



plant parts? How does the rising curve of cumulative input, 

the integrated form of equation (I), vary from year to year"* 
From place to place? Are most of the variations predicuble 
from a fairly small number of ecosystem parameters (like 
leaf area index, LAI) and environmental variables'' 

Such questions thus involve time responses ranging from 
seconds or days to months and jwars. Ilie Productioa Pro- 
cess (PP) section of IBP has tended to focus physiological 
interest, especially toward the faster processes, and all the 
rates of change expressed in equation (1 ). Eadi btome 
theme group in Terrestrial Productivity (PT) is interested 
in the integral of these changes over whole seasoiu, and its 
eeologkal prediction. One approach to piedietlon is through 

mnrJcls with fine resolution and insight (but also exacting 
requirements for input data), to test how well all the com- 
ponent processes forecast tbeta' total result. Yet because 
such tests arc feasible in very few places, complementary 
models calling for rather few predictors Qtke standard cli- 
matic variables) aie still needed. These are being improved 
and calibrated empirically to ntionallie the re^onal patterns 
of the world. 

Models of either type can provide a scale against which 

to compare estimates of total ecosystem production and 
of that fairly small fraction of production which n currently 
used or usable by man. Both types are desirable. 

Respiration of the green parts (Eq. 1) Hmits the magni- 
tude of surplus production-organic material or energy ex- 
portable for building and maintaining nongreen plant parts, 

Surpliu production (SP) = Export Irom leaves (and twigs?) 

» Nel piiimrjr pradttctioii (NFP) * Rn(iiim»t» |Mm (2) 

The last term, respiration of nongreen parts of green plants, 
is an additional tax limiting net primary production. It is 
Still not clear how much both respiratory taxes in (1) and 
(2) increase as a function of income rate (i.e.. as a kind of 
"Income tax" on photosynthate, sensu Olson, 1964, p. 107) 
or of biomass and condition of the respiring tissues (as a 
"property tax"). Perhaps photorespiration partakes most 
of the first aspect, and dark respiration of the latter, but 
that correlation need not be a sharp one (cf. Richardson ei 
1973). Relations between respiration of green and non- 
green parts, light and dark itmes. and "income" vs. "prop- 
erty" tax models hopefully could be aided by radiocarbon 
or organic tritium tnoerworfc to clarify the trandocatlon 
as well as the prompt turnover of plants' labile and non- 
labile pools of organic material (cf. Harris el al., pp. 1 16-1 22). 

In prindple,iierprilliMi>y iwodluciftNi riioiild he measur- 
able, by dennition,from photoqrnthesismbitts plant res- 
piration (3a). 

HPP ■ OPT - XuMMi pint partt 

-'totharpwIaorsiMNplaais (3a> 

-dBloiiiaH,I.M-^^ (3b) 



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PRODUCTIVITY OF FOREST ECOSYSTEMS 



35 



TABLE 1 Preliminary Forstt Productivity Eitimata$, BaMd on 1972 IBP 
WomIiimI Piojict Ntpofti, FintOfdir MoiMiMid ftMitwiil Modrit (Pram 



Maior Forett and VAnikdlsinA 


Mel Primirv 




f^rnftC Primarv 


Ecosyitem Group 


Production 


Production 


Production 


Cool iMHiptntc to boiMl 








CMillirrMMt 




1,«M-2A00 


2.3S0-I,8N 


THDfmto dwiikHim f oNMi: 


1.440-1,780 


2.100-3.680 


2.360-t,2S0 


Oalc 


1,400-1,944 


2^20-4.210 


24«M,M0 


Other 


M90-2,100 


2jOO»-3i03O 


336&-3.S30 


Warm Icmpeiiiic bioiidleavcd 








eveixrecn fomti 


UO-l,SOO 


3.393-3.100 




Drapfcal «faiBMea fonti and 










743-2.100 


U23-7.370 


3.400-12.730 



In practice widespread data are Iweoming available, but only 

by a complementary approach (note 3b). This is from care- 
ful measurements of plant biomass change {^B)ptus allow- 
ance for the appropriate losses (L) of produced material in 

the time interval. A;. In almost exact parallel with Coup- 
land's critique for ^asslands (pp. 44-49), it seems fair to 
say that upward correclions of Z, are still needed. Some 
components of litterfail may be missed (e.g., coarse branches), 
while others (leaves, flowers, fruits) are underestimated due 
to decay or consumption. Missing or preliminary terms arc 
being corrected by the working group, but general magni- 
tudes for production estimates <M' the tour forest groups in 
the Woodlands Workshop arc given m Table 1 (after Keichle 
etd,, I973e). 

Leaf Production 

In seasonal forests, some early leaves, stipules, and repro- 
ductive parts are typically shed before annual foliage 
readiea Its maximum value. Year<round littcrfaH coUeetions 

provide a minimum correction for such loss, hut the easy 
decomposabihty and leachability of some of these soft ma- 
teiials (before falling or even widiin the litter traps) caflt 

Sor augmenting such a minimum correction.* 

Production of understories and groundcover may be 
un dete i ti ma ted because of asynchrony of harveit times 

and growth phases, and (<ther problems discussed in chap- 
ters on grass and sttrub systems. Lower strata (and uncer- 
taintias about their praductivity) might be relatlvaly un- 

* In rainforett, as at the Pasoh project in Malaysia, 1 was ihown ap> 
ptediiirie maiiet of Dipterocarput and other leaves faUen from dw 
oycntory but "hung up" (decompotinft somewlnt cn route) in dw 

undcrstory canopy IjyL'rv bcrnrc raini and winds Imally brougilt 
the partly decayed debris down lu the litter trap*. 



important in large, dense forests compared with problems 
of eatimatfaig primary and secondary production for the 
main tree strata. The simpurication of past studies could be- 
come increasingly misleading as ecosystem atudlaamovt to 
open woodlands and arannii in poat'ISP yean. 

Abovegraund Support Structures 

Stem biomass, and hence production rates, has been sub- 
divided somewhat differently among IBP projects. Current 
twigs have too seldom been distinguished from and re- 
lated to other stem material and (leary) preen parts 

Reproductive "support" structures (llowers, iruils, etc.) 
are recognized as highly variable but ecologically Important 
fractions of the plants' allocated production. They are 
seldom a large part of the total production (for trees), but 
esttanatea need to be filled in where missing, or deaeg^ 
gated in cases where they have been pooled with stems Of 
with foliage, in order for results from different projects 
to have comparable meaning. Aggregation of unlike com- 
ponents can often he avoided for a major species or group 
(and for a "target" group of interest for management even 
if it is not the moat abundant one), but tn descriptive 
modeling groups that are less abundant or lower ui Stature 
often tend to get lumped together. 

For trees of diverse size, the fundamental biological 
problem of relating dimensions (allometry) has taken on 
very practical importance: e.g., using easily measured diam- 
eters (and perhaps height) for estfanatbig more difficult 
measures like biomass. It is natural for these statistical con- 
siderations to be applied first to biomass, but there is some 
progress in making application to production rates (Ho- 
zimti et al. , 1968, 1969). The common tendency to under- 
estimate aboveground biomass is still one contributor 
toward unt/emtimation of some productivity rates. 



Copyrighted material 



36 



MRVt. OLSON 



BELOWGROUND PRODUCTION 

As with other ecosystems, woodland studies have had fur- 
ther errors (again usually estiinating on the low side) for 

production (V'n' >ts and other belowgidund parts. 

Root mass poses f ormidable problems. The buti root or 
undensrotmd fxtrtion of stump and the immediately adher- 
inj: ' ill - il 1; iM-s (or buttresses in the trnpiis) , m and should 
be treated by turther extension of regression methods al- 
ready noted for aboveground supporting structures. Other 
lateial roots of diameters down to the convenient 0.5 cm 
dividing line can be treated similarly, but with much labor; 
or coring devices of sufficient strength can provide a 
broader sampling if soils are not stony and the trees are 
not extremely massive (cf. Harris el a/., pp. 1 16-122 ). 
Roots smaller than OS cm call for the core approach plus 
meticulous separations, and problems of interpretation 
like those discussed by Coupland (pp. 44-49). I also stress 
the active role and turnover of a very fme fraction (e.g., 
bdow 0.1 cm, cf Olson, 1968), and urge attention to 
the very special role of myccorhizae in the rhizoiphere 
of the forest ecosystem. 

Contlniial or episodic death of each root size class is 
probably underestimated Inrome must make up for root 
mortality and for debris and exudates cast off by still* 
living roots, in addition to providing (ot net increase of 
root mass over the years. Especially since the IBP root and 
rhizosphere symposium (Ghilarov ci al. , 1968). the nature 
of this problem has been appreciated. Working hypotheses 
that a fairly high underground production allows for this 
replenishment have been built into some total production 
estinnlai by Rodbi <r af. (pp. 13-26). How these Iqfpotlip 
eses will be refined numerically is one of the larger issues 
requiring attention during the synthesis of IBP research, 
and the extensions of newer methods (Uke isotope t^ging) 
in later yean. 



HETEnOTROPMIC PROCESSES 

In many of the ecosystems utilized by man, harvesting re* 

moves products for ultimate decay or burning at some dis- 
tance from where tliey were produced. A few ibp projects 
have li«l die opportunity fot ehborating studies of animal 

food chains which respire some of the produced orguiie 
materials before decomposers oxidize the remainder, e.g., 
beech forests of Germany and I>enmark and subalpine 
( Tsuga divmifolia) woodland of Shiga Heights, Japan. The 
animals not only release some fraction of what they con- 
sume and assimilate, but hasten the change of additional 
plant material from "live" to "dead," thereby initiating 
decomposer activity earlier and at a higher rate than might 
have occurred without aggressive herbivores, predators 
and omnivofes. 



Herbivores 

Rates (1970). Franklm (1970) and McCuUough (1970) to- 
gether review the wide biterest in prbnary consumers in 
forests. The conventional wisdom is that ver>' few percent 
of net primary production is channeled through animal 
food chains in "normal" years. Yet observation of our 
l.iriodciuiriin tulipifera forest in Oak Ridge, Tennessee, 
over a decade suggests that geomeliid caterpillars, weevils 
and aphids may each take turns hi different years drawing 
off more of the flow of orpnic carbon or energy than their 
siiaie in years of average population. Wtien all consumption 
of aO canopy horixons is summed, with or without rough 
estimation of the underground feeding (Ausmus et al. . in 
press) on roots, early estimates of consumption (e.g., Reichle 
and Crosdey. 1967; Reichle et 1973b; Van Hoolc and 
Dodson, 1974) may well be increaMd 

Studies of oak forests near Grange-over-Sands, England, 
and east of Cracow, Poland, have provided relatively com- 
plete energy flow budgets. The Utter example (Medwecka- 
Komas et al. . 1973) was marked by conspicuous defoliation 
by lepidopteran larvae, typically followed by a second flush 
of oak (Quercus robur) foliage that is presumably produced 
with labile or previously stored photosynthate In 1969, 
consumption studies allocated 0.032 X 10" and 0.108 X 10* 
gram calories per m' of ground area for Tortrix viridana 
and other caterpillars respectively; the sum of 0.14 X 10* 
calories per m' accounts for most of the 0.1S6 X 10^ 
cal/m' (30.6 g/m' ) estimate of area r e m o v ed from leaves 
from May to November. The two-year average of estimated 
consumption was 0.41 X 10* cal/mVyr (80.8 g/m^/yr), 
BO 1968 (a jreer of nearly complete oek defoliation by ToT' 
trix) had ahout 1 ''O p'nr /yr removed. 

Compared with such isolated examples for deciduous 
forest, we expect the conifer forests (both tempemte and 
boreal) to show even greater contrasts in cnnsumpiion be- 
tween pealc years of a forest pest cycle and the many m- 
tervenfaig years. Airphme views of Siberia and of Nbidi 
America show the vast scale (and sometimes sharp boumlF 
aries) of devastation; essentially starting new cycles of eoo* 
system development by succesrion instead of minor per* 
turbations on previously existing stands. Forestry research 
in many countries, of course, is analyzing details on the 
biology of both pests and stands, but synthesis integrating 
a balanced understanding of stands, pests and their con- 
troUii^ agents is high on ttw list of prioritiBS for post-lBP 
years. 

Piedeiofs end Perasliie 

The examples just given of defoliators and of Other pestS 
illustrate the role of secondar\ and tertiary consumers in 
having a "leverage" on the quantity and quality of ecosys- 
lams* primaiy produetioii-out of pioportioa to die flow 



Copyrighted material 



PBOOUCTIVITY OF FOREST ECOSYSTEMS 



37 



of nutter and enerfy through these consumers. One of the 
fCHOHtwby fCKiicli nrait comUw MMtbnMdof thin in- 

dividtml stands is the wide ranee of some of the larger 
predators. Those parasites and diseases which pass through 
a popuhtioo eyde only in locd refbgia and then ipiead 

out d»o require some attention to regions large enough to 
ilhiatrate all significant stages of the population cycle, and 
of the luidieape pettem* which control it. 

Obviously not ail stands, or even all ecosystem types 
in a large or heterogeneoui region can be investigated in 
equal detaB-eapedaHy in meh detail as IBP caaa itudiei 
have sought. Yet the local detail seems necessary to reveal 
the normal role of predators and parasites as they relate to 
herbhoies and primary prodooen. We need not only to aum- 
marize and mode! on different scales (cf. Olson. 1971 ), but 
also to couple subsystems which must (by their nature) be 
Investigated quite locally with problemaiviiioh call for 
sampling and probability statements (at least) on one ^ 
the large icgiogRal scales. 

Seawangers and Omnivortt 

Aniong secondary consumers, not only predators and para- 
sites but also scavengers channel some fraction of the ma- 
terials and energy from the herbivorous trophic level. By 
hastening the return and redisperial oi nutrients over the 
ground, these organisms, too, play a role of somewhat 
broader significance than would be indicated by the frac- 
tion of primary production which is assimilated or the 
much larger fraction consumed by them. Neither vertebrates 
nor invertebrates can be dismissed as generally unimportant; 
but measures of their absolute and relative importance can 
be derived only from the more detailed eoo^stem analyses. 

Many animals (including some social insects, STnall mam- 
mals and certain birds that are "granivorous" when seeds 
are available) derive only parts of their diet from other ani- 

mals. We need better estimates of what part - and when the 
consumption is switched-during the seasonal cycle and per- 
haps the life eyde. 

.Among omnivores we can highlight man. His ro'c as a 
coiuumer witliin eco^stems has long attracted interest of 
environmental anthropologists, and began to get broader 
public attention in the late I960's. In the U.S., testimony 
to the Congress related to IBP itself was among the many 
channels by which the environmental coooem reached 
points where major policy dedsions on the human eoviron- 
ment were to be made. 

DaBBaapos t tion 

The coupUng of subsystems to large-even gfobal-systems 
is especially challenging for soil processes. Microbes, meso- 
fauna and many media are small enough to be subject to 
experimental manipdation indoors as well as in die Held. 



In forest stands, even moie than in some other systems, 
however, tte ih la osphete is readily distorted by the tedi- 
niqucs of study (Ghilarov , 1968). On landscapes* 
production Irom the uplands may become balanced in part 
by nspiratkm from leaves wMdi have blown downhll or 

humus which has washed downstream. 

Yet as we integrate over larger areas, microbial and 
other heterotrophic respiration (and flra in many regions 
as well) must come to approximate more closely the auto* 
trophic production. For a whole large ecosystem or re* 
gkmal complex, we are tempted to view die implicetions 
of balance (or of imbalance as the case may be) which v/as 
reviewed some years ago with mote particular regard to 
Utter and sod (Olson, 1963). »r*s own contributions to the 
study of heterotrophic p ro c e ss e s ava Ml for others to 
review, 

raODUCTION OF FORESTS AND OTHER BIOME 
AREAS 

A geographic index of world ecosystems (Olson, 197Qb) 
was complemented by a generalized map of living orpnic 
carbon Onside back cover of Reidile, 1970). That map 
represents continental patterns approximating present dl* 
matic conditions (i.e., following the major postglacial 
migrations onto formerly glaciated areas) but before the 
major clearing of forests by man. Although labelled "prior 
to the Iron Age" the map perhaps approximates patterns 
and magnitudes corresponding with the early NeoUthic. 
Late Neolithic and Bronze Age societies my have abeady 

reduced the areas and especially the average masS per unit 
area of forests on the lands they occupied. 

Woodtand Areas 

There is considerable discrepancy between the arees esti- 
mated by foresters to be either woodlands or forest, and 
the larger areas estimated by iiazilevich, Kodin and Rozov 
(1970) from careRd study of the USSR Physkal- 
("icopraphical Atlas nf the World (Scnderova, 1964). These 
Soviet sources indicate about 17 million km' for boreal, 
(ubalpine and various "semlboreel** forest zones (including 
"hcmiboreal") and over 18 million km' for temperate 
wooded zones. Included in the latter "temperate" area is 
about 1 mflHon fan* of **moist stte" woodlands and open 
communities fas on floodplains) in semiarid to arid climaiaa. 
The tropics include another 17 million km' of forest and 
woodland and 14 million fan' of woody savanna and 
scrubland. Thus a total of 66 X 10* km' could well have 
been considerably wooded SjOOO to lOjOQO years ago 
(early Neolithic time). However, this atbS4neasQring ap- 
proach does not yet hint at how much of each area was 
locally in nonforest cover, nor how much of the IS XIO* 
fan* of eultlvalad land would have lobe aubtfactadfiom 



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cimvs.ounN 



each kind of original woodland to account for subsequent 
conversion from forest to agriculture and grazing. 

Starting from various United Nations sources, estinutes 
of forested areas range from 40 to 44 X 10* km*. These 
inventoriet apparently exclude stu'u' .jMiMisive ipen wuod- 
land ecosystems that are valued (and are therefore reported) 
priiiiaiily for grazing, i.e., as rangeland. This omission prob* 
ably outweighs the incongruous naming of ArubbUKl tt 
forest, in countries where wood is scarce or where even 
small stems are especially important for fuel and light con- 
struction. 

Between the extremes o!'40 and 66 X 10'' km", my esti- 
mate (Olson. 1970a) of 48 X 10" km* tor current forest 
and woodland has since been adjusted slightly (by 2 X 10^ 
km' to include partially wooded "moist sites" in Olson el 
aL, 1970, or by 1 X 10* km^ m the 1973 reprmtmgof 
Olson, 1970n). Several other recent estimates reviewed by 
Whittakcr and Likens (1971) are generally comparable for 
the temperate and boreal zones. 1 believe that they imply, 
however, a greater area for tropical rainforest than is war- 
rantee' hv ^L-ncral observation ind by Ovington's recent le* 
view (see ioolnote, p. 33). 

To improve much on the present estimates of forest 
areas will probably call for mure sopliistic.ited forestry and 
ecolo^cal survey statistics, especially in tropical regions. 
Eventually all our estimates of vegetative cover wdl need 
to be ovalualed by remote sensing imagery and multispeclral 
scanning, partly by satellites but partly from aerial photog- 
raphy and extra ground sufv^ in tteai wheie the ioteiprt' 
iilion oriandicape pattern is critical. 

Borsal Woodlands Compared With Polar Zones 

Bazilcvich, Rodin arul Rozov (1970) estimated less than 
500 g/m'/yr of prodoctioa and less than 7.000 g/m* of 
biomass for tundras and bogs (mostly in /ones 1-3).* High- 
er production occurs on mountain '^tundra" meadows on 
black soils and higlier biomass on certain wooded tundia 
(Table 2). Table 2 also compares these tundra-like ecosys- 
tems (mostly Polar zone) with forests and related commu- 
nities of the Boreal zone. In zones 5 to 7 (northern, middle 
tad southern taiga), estimated average productivity in- 
creased southward from 500 (o 7^0 ^'m' lyr but live bio- 
mass (including estimated roots) mcreased even more from 
12^00 to MfiOO g/m'. Similar ranges exist for values for 
subalpine and montane conifer woodlands, but 1 ,(XX) 
g/m^/yr productivity and 35,CKX) g/m^ of dry matter were 
estimated for "mixed forcit" (zone 8) on the richer soOs. 

Biomass, productivity and Itxa'inn of forest ecosystems 
are brolien down further by typical plant/soil habitats for 
each rotjor aoosystem complax in TaUe 2. By multiplying 

* Hie nap lonn referred to aic tiioM of Baiiievich and Rodin 
(1967) and modifioBtions bjr Olion (I97(N>). 



area times masa per unit area and summing over zones, we 
obtain an estimate for taiga of over 6.8 X 10* metric toris 
per year as the production rate (net primary productivity) 
and a live organic mass of 2.S X 10" metric tons. For the 
varied systems lumped as "semiboreai" (including extensive 
birch, aspen and some other hardwoods in zones 7-9 espe- 
cially), the total production rate was estimated as over 4.20 
X 10* metric tons per year by an inventory of about 1 .3 X 
10" metric tons. Summing boreal and semiboreal values 
gives estimates of 1.1 X 10'" metric tons exchanging on a 
total of 3.79 X 10" metric tons for the combined original 
area of 1 7 million km' (much of Canada, Fennoscandia and 
the USSR). 

Comparing these estimates with the corresponding sub- 
totals for all the high latitude tundras and related ecosys- 
tems (including bugs) at the top of Table 2, we find the 
boreal and semiboreal ecosystems oceupyiiig only 25 per> 
cent more area. However, ret primary production is here 
estimated as 270 percent and dry mass as 820 percent as 
high aa the tundra and related eco^stemt taken together. 

I n iifiei ana noafnaniis 

Compared with the "semiboreal," boreal and polar zones, 
the temperate forest has consistently higher productivity 
and biomass both on a unit area and total basis (Table 2). 
Preliminary pre-agricultural estimates of Bazilevich et al. 
(1970) for both the cool temperate conifer forest (espe- 
cially in the northern CordiOera ranges and vaDeys of 
western North America) and for the mostly deciduous 
forest (of eastern North America and western Europe) were 
each nearly the same in area (~3.8 million km' ) and in 
productivity (4.S X 10^ metric tons/year) and ta maas 

(~1.3X 10" metric tons dry matter) 

The appropriate estimates for area ul "giant and coastal 
conifers" (mostly from northwestern North America) wiQ 
be revised by work now underway in the Coniferous Biome 
program uf the US-IBP. The mass and productivity per unit 
area for this catagoiy will be higher than pmioiialy iup> 
posed (cf . Fujimori . 1971) 

Most temperate forest is bruadleaved deciduous in pre- 
vailing aspect, but different coniferous groups can be fan* 
portant in the broad transitions toward both the Boreal 
and the Subtropical zones. For example, the "Northern 
Forest** of eastern North America (**Northem Hardwoods" 
of foresters) includes shade tolerant Tsiiga canadensis 
(eastern hemlock) in niany habitats that are moist and/or 
free of fire; thta apedei extends south to Alabama in the 
Appalachian Highlands (Olson, 1971) Iri the Great Likes 
St. Lawrence forests and Acadian portions of the "Northern 
forests'* whkh straddle much of the eastern Canadian^JSA 
bi>u;uJary, various pines were important since early post- 
glacial tune, and probably expanded by wildAre and by 
man's influeiiGe over miqy areas that otherwise mi||it have 



Copyrighted material 



pnoouenviTv of romar foocmsM 



41 



devdoped through ecological roccenion towird a monic 

of deciduous and mixed forests. 

It is still difTicult to judge whether the biomanand 
productivity estimate* of both the Cool and Warm Tern* 
pei«taxanMillTUbte2anapprupnate averages overwid« 
areas or not. More mawive and prsvJuctivc stands t!ian 
those for the average stand Uu exist, ami these may have 
been ghwn a disproportionate representation among the 
diverse forests (Whittaker and Woodwell, 1971 ; Olson, 
1971) which intluenced Bazilevich ei ai. (1970) in their 
cricuiations for broad geographic averages. Warm, mostly 
humid, temperate forests with varying mosaics of decidu- 
ous and/or evergreen broadleaved forest and some conifers 
(c^, aoutlNni pinra) wm taken as having higher produc- 
tion rates than the combined cool temperaie forests (per 
unit area and total). Although these forests have lu^^er bio- 
nuw per unit area, their amaOer area (5.8 mfllion km') gh«i 
a slightly lower total biomass of 2 27 y 10" metric tons. 

Semiaiid climatic types include open woodlands (e.g., of 
pine, juniper and oale) and also tlie dmie but tomewhat 

Sti;ntcd forests of regions with winter rain and summer 
drought (Mediterranean-type). In arid and semiarid climates, 
as in tlie warm humid ones with rooiit dtestuch at flood* 
plains havim abundant nutrient leaenes, extraordinarily 



high production iatei(4jOOO to 13,000 g/m Vyr) are char- 
acteristic of quidc-trowing trees, thickets and luxuriant 
herbs. Biomaas per unit area in these ecosystems is assumed 
to be lower than for other forest types because the upper 
canopy is typically less dense. 

Together the estimated 18 million knr oripinally wooded 
in the temperate zone were inferred to have an annual net 
primary productivity total of about ~-3.6 X 10'** metric 
Ions/km^ /yr, on an inventory of 5.82 X 10" metric tuns/ 
km^. These figures may be liigh, because relatively well-de- 
vdoped ttandsweredioaen for siu^ and then extrapolated 
over large areas which included medium and pOOr gvOWth 
as well as very productive stands. 

For tropical woodlands and many other qritems better 

estimates can he anticipated from other hiome programs. 
Preliminary estimates (Olson, 1974) will be discussed only 
bdefly fai terms of carbon dioxide axchanie- 

ForeMa in tfia OlolMl Carbon Balance 

In Table 3, preliminary estimates of organic carbon inventory 
and exchartge are based on assumptions uf carbon percent- 
aiM langUw Cram 43 to 49 percent forn^ plant parts. 
While improved oonvershm factors will modify details, such 



TABLE 3 Nat Primary Production, Carbon Pool, and Turnover for the Major Terrestrial Ecoaystams 
wHh Empkaria on Feraati {Fnm Otoon. ^VHf 



l*ro<luction* 

(10* metric tons Live Carl>on Pool Turnover I rMttO*'' 
Ecoiyjtem CompleiM of carbon per ytu) (iO* lom) (pwyear) 



Nonvioodtand 



Tundi.1 and bug (treeless) 


0.88 


8.08 


0il09 


'Tundia" meadow and scrub 


1.46 


13.20 


0.1 


GcauJand (subalpine (o tropical) 


10.27 


30J9 


0.332 


Daiarts (exeludiag kwai moisl atesi 


347 


B.SB 


a394 


TOTAL 


15.98 


M.75 


aa6' 


Forest, woodland 








Boreal taiga 


3.33 


121.80 


a027S 


Semiburedl forest, woodland 


1.93 


64.12 


0.0301 


Cool tcmpeiate. montane conifer 


2.08 


68.38 


0.0304 


Cool lempeiatt, nMttly deciduous 


2.09 


67.88 


0.0308 


Wwm lempMite, noitlir bioadlnf 


4.0S 


97.76 


a0414 




M7 


1IK32 


0.3878 


Wann, montane, woodland (samiaiid) 


240 


24.80 


00968 


Wiim temperate wetftnd (aifd to laniiarid) 


3.14 


13.82 


0.2449 


Tr{ipi^:il iKh wclldni! ( jnd to semiarid) 


9.79 


2j68 


0.2970 


Triipk.il skr,.lj. 'J. ni id;.iii.J savanna 


10.52 


139.13 


0.0756 




4.08 


9942 


0.0410 


Tropical lowland rainforest 


11.17 


83.86 


0.1331 


Other tropical forest 


10.82 


216 26 


0.050O 


TOTAL 


59.37 


1.009.41 


0.059^ 


TOTAL LAMD 


75.35 


1,070 


aoTrf 



'Bqulvalml lo Uw gnm primary produellon Urn dw mpbailloii oT M puU of giMB plaala. 
^Includw cttoo Mad «y In aH IMna plmti. 

<^ Annual loMorciriNm AoMi Uw Uwa carbon pool to dead urisak meitar. 

'^olal tunover tit l nwlas sea not additivw of individttal valuet, dnea lotd avuaga turaoiwc fractioas an weighted toy pool 
rina for each ecaajratm coaplax. 



Copyrighted material 



42 



JERRY t.OiMM 



adjustments arc not likely to be as critical as improvements 
in the estimates of bium a ss per unit area already considered in 
Tables t and 2, and assignment of immbersto 
of ecosystem area in Table 2. 1 have made slight downward 
adjustments from BazUevich, Rodin and Rozov (1970) for 
tundra ^sterns. «Mdi have little tofluenoe on the total. 
However, my preliminary readjustment for tropical rain- 
forest more significantly affects the estimated world carbon 
balance. Otherwise Tables 2 and 3 intentionally retain these 
autbon' estiinitct for other ecoiyilenis pending lattr ra> 
vision. 

Personally I still consider these estimates as upper bounds, 
and this impression has just been eonfirmed by the Wood- 
land Workshop. Undoubtedly many Stands are as massive 
and productive as outlined for each zone in Table 2. How- 
ever, tome or these may represent the upper range of a fre- 

qut'Ticy dis'ribuMini nf mass per unit area. Mean >n expected 
values should be smaller-even for the pre-agricultural con- 
ditions of postglacial ttanes. 

Man's own activities then diminished both tlie extent of 
forests and mass or carbon per unit area. We have only pre- 
Ifanhuiry estimates of what man's hiput on the terrestrid 
ecosystem carbon budget has been (Olson, 1974). but even 
these sliould iielp lead to a broader perspective on tech- 
nology's role In changing global geodieinistry. 

Annual turnover, in terms of the net primary production 
and equivalent lois of plant organs, was apparently only a 
f«w percent of the biomaas or carbon inventory for ill but 
some tropical forests. Of course, respiration of green and 
nongreen organs would add very thort-Uved components to 
the nearly continuous spectrum of residence times which, 
by definition, cover such a wide range for aU the ^temi 
wfikh we call forests or woodlands. 

HEFERCNCES 

Andemon, F. 1972. Syitemji analyju in northern coniferous 
focMtt-IBP workihop. Eootogical Research CommittM 
Bvlledn No. 14, SiradiA Natwil Scshks lUieaich ConncU. 
194 p. 

Anmuf. B. S.. J. M. Ferris, D. E. Reichle, aixJ E. C. Williams. In 

pfcs*- 'IliL- r..i]L' i>t p:ini.ir\' .(insunicr^ in fi^rcst r.Mit priKCXSirs. 
US-IUP Inlerbiome Symposium: tlie bcluwground ecosystem: 
a synthesis of plant-assoei^tcii pnKcsscs. 
Buitevich, N. 1.. uti L. E. Rodin. 1967. tUps of ptoductiviiy and 
uie wiMinicii cydc m ue nrai vpmopai mnnnuieBBiaiiOB 
typw. [tvertian Geognptikfteilcqgo Obilwlwrtvt. Unlnpad 
99(3)M 90-194. 

Bazilevich, N. I , L F Rodin, .inJ N N Ro/ov 1970. Geographical 
as{)ccts oi' biological productivity. Papers o( the Fifth Congress 
of the Biological Society, Leningrad, USSR. 28 p. (Translated 
in Soviet Ceognpliy: Review in TramUtioiii. May 1971, p. 219- 
317) 

Du*|g)Maud, P. (cd.) 1971. l>rodiKti*ity of femt aeoayilann. Fio* 
oeedingt. Bmisels Symposum, Octolier 1969. UNESCX>, Firii. 

707 p 

Franklin, R. T. 1970. tnwct influences on Uic forest canopy, p. 86- 
99. /« D. E. Rakhle (ed.) Analyrit of iMperale fomt ecocrf 



New York. 

Fujimori, T. 1971. Prirtxary productivity of a younj.' Tsuna ht u ro 
phvtla stand and some speculations about biomiss of forest com- 
munities on the Or^on coast. Pacific Northwest Forest and 
Range Experiment Suikm, Fonal Service, USOA, Portland, 
Orqton. 1 1 p, 

Ijhiiarov. M. S., V. A. Kovda, L. N. Novichkova-lvanova. L. E RodlB, 
and V. M. Svcshnikova (cd.) 1968. Methods of productivity 

^'lJll^l s <n [iM.>t syNtcmsaitd rhizoiphere organisms. International 
symposium, USSR, August-Septcnit>er 1968. Nauka, Leningrad, 
USSR. 240 p. 

Hosumi, K., K. Sbinoiaki. and Y. Tadakai. 1969. Studies on the 
ftaqnenv diitrJbuiion of die weiihl oriodiiMnal tteeslB a 
fomt stand. 1. A new approach lowaid the anahriis of the dia> 

irtbutlon flitictlen and the -3/2th power dfittllmtion. Jap. J. 

Moiumi, K... K. Yoda, and 1 . Kira. 1969. Production ctolug) ol 
tropical rain forests in southwestern Cambodia. 2. Pliotosyn- 
llietic production in an cveqrcen seasonal forest. Nature and 
Life in Soulbeait Asia 4:S7-B1. 

MeQiHoiiih. D. R. 1970. Secondaiy pradncdoB of Midt and warn- 
nab, p. 107-1 30. In D. E. Reichle (ed.) Aaatytia of tamparaM 
fore&t ecn yvtoiiis Ecological sludiei I. SpiiBgai-Veflig, BailiD- 

HcidL-lt5cr(!-Ncw York. 
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lirKtity How in the deciduous woodland ecosystem, Ispina project, 

Poland, p. l44-lS0./n D. E. Reidile, R. V. OHeBI. and J. g. 

Olaon Icomp.) ModcUoB foraet aooQralania. Raport of laMma* 

tional Wocidlandi Woiksitap, IBP PT Scedoo, Angmt 1972. 

EDFB-IBP-73-7 Oak Ridge National Lab., Tenn. 
Olson, y. S. 1963. t^lncrgy storafic and the balaiKC of producers and 

dccompowri in ecological systems. Ecology 44(2):322-332 
Olson, J. S. 1964. Gross and rwt producUon of terrestrial vegetation. 

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a lantd Nieaopliiydc AppaiachiaH font! in Tcnaenee, p. 133-13S. 

/■ M. S. Ghlaio*, V. A. Kovda. L. N. NoviciikovaJvaBoiia, L. E. 

Rodfn. and V. M. Svtdiniicova (ed.) Method* of productivity 

■;ru.iit \ in root systems and rhi/ospticre organisms. lnlernation.aI 
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USSR. 

Olson, J. S. 1970a. Carbon cycle and temperate woodlands, p. 226- 
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NewVoik. 

OlaoA, J. 8. 1970b. GecsnpUe Index of world ecotystemt. p. 297' 
304. In D. E. Reichle (ed.) Analysis of temperate forest ecosyi^ 
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Ncw York. 

Olson, J. S. 1971. Primary productivity: temperate forests, espe- 
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(ed.) hoducdvity of foaeitec w awlet. Pkeeeedii«s, Bnaab 
Symporiimi, October 19(9. UNES(X3. Pink. 

Olton, ). S. 1974. Terrestrial ecofytlcm. Encyd. Brit. I B:144-I49. 

Olson, J S , J H Hilmon, C. D. Keeling, L. Machla. R R^-vcHl- 
W. W. SpoiiorU. and F. Smith. 1970. Appendi.x: Carl^in cyilc 
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MIT Plan, GMnbrid8e> Mmi- 

Ovii^on, J. D. 1962. Quantittrtli» eeoloBy and the woodtend eco- 
system concept. Adv. Ecol. Res. 1:103-192. 

Ovin|;ton, J. D. 196S. Organic production, tunover and mineral 
cydini in woodlaada. BtoL Rw. 40:29S-336. 



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43 



luret, F. M. 1970. Estknatien orih« efrects of phytophii^out iO' 

sects on forest production, p. 100-106. In U. E. Reichle (ed.) 
Analysis of (emperaie foie\l ecoivsiciDv. I cologicjJ studies I. 
Springer-Vcrbt:. Ucrlm-lloiJilhcrii-Ncw York. 

Rekhle, D. E. (ed.) 1 970. Analysis of (empciate Tore*! ecosystems. 
Ecolocfcal itudk* I, Sptiagtt-Wtan, Berito-HeUdboy-New 
Y«riL3(Mp. 

R«idde, D. E., and D. A. Cmatef, Jr. 1967. IivmtiiMion on het- 
erotrophic productivity in forest insect communities, p. 563- 
587. In K. Petnjscwicr (ed.) Secondary productivity of te»» 
n sin.il ecosystems (principles and methods). Vol. II. Proceed 
int s, U iirkinn Meeting, Jablonna, 1966. Polish Acad. Sci. 

ReKlilL , I) r.. B. E. Dinger. N. T. Edwards, W. F. Harris, and 
P. SoUins. 1973a. Carbon flow and atotage in a fomt ecoqrr 
Mm. I*. 34S-36S. Af G. H. WoodwcU and E. V. Pwan («d.) 
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Atomic Energy Comm. CONr-720510. 

Reichle. D. E.. R. A. Goldstein, R. I. Van Hook, Jr., and G. J. 
Dodsofl. 1973b. Analysis of insect coa«lMtptloilina(bmt 
canopy. Ecoloty 54i5):1076-l083. 

Iteicliln,D.e..R.V.O1lell,aiidJ.S.0lacm|eainp.t 1973c 
Moddiflf foretl MoqrsMns. Report of Intantliaml Woodlantft 
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Ridge National I-ab., Tcnn. 339 p. 

Rcincri, W. A., L. H. Allen, Jr., R. Bacaslow. D. H. thaalt. C. S. 
Ekdahl. Jt , G, Likens, D A, LivingMone. J. S. Olson, and G. M. 
WoodweU. 1973. Appendix: Summary of world carbon cycle 
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Ywk, Itagr 1972. U.8. Aloale Cncqgr Conmi. OONF-720S10. 



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stomatal rcue.uu L-. photopigments, nitrogen, water p<itcntuL 
attd radiatiuii ;o estimate net photosynthesis in /.inot^e'/K/z-o/i 
tulipijcra L. -u physiological indOL EDFB-lB^7a>l3, fMk RidlB 
Nationjl I ;ih,. Tcnn. 1 30 p. 

Senilcrovj.G. M. (ed ) 1964 Physical-Geographical Atlas of the 
World. USSR Akad. So. and Main Admin. oTGeodeay and Git- 
ln§rapliy. 

Shidants of Earth's Euturc. 1 97 1 . Earth'* ataloKjr actloa nmei. 
SEP, Oak Ridge, Tenn I p 

Van Hook, R. I., an^i C, J I)MtU(in. 1974. Food energy biidccl lot 
the yellow-poplar weevil Odoniopiit catcfatut (Say). Ecology 
55(1): 205-207. 

WhUtaker, R. H.. and C. E. Likens. 1973. Carton to the Mola. 
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in the Uoipbetn. hooaadfcip of SbnHpoiten*. itnoMMm Na- 
tional Lab.. Upton, New York, May 1972. U.S. Atomic Cnersr 
Comm.CONF-720510. 

Whittakcr. R. H., and G. M. WoodweU. 1971. Measurement of net 
primary production of forests, p. 159-175. In P, Duvigneaud 
(ed.) Productivity of forest ecosystems. Proceedings, Bruanb 
^podam.Octoter 1969. UNESCO. Pwlt. 

Woodwci. a IL. and E. V. Pecan (ed.) 1973. Outon and Ik* Wo- 
sphere. Proceedings of Symposium. Brookhavta NallOMt Uik, 
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400 p. CONr-720510. 

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Yoiii«. H. E. 1971. Pornt WmniM antdlei. LHb ScL and ApL Bxp. 
Sla.. Univ. Maine Pmai, Ofono. 2S0 p. 



PRODUCTIVITY OF 
GRASSLAND ECOSYSTEMS 



R. T. OOUPLAND 



ABSTRACT 

The contritatttkMU made during IM* to the tcchniqiiei «f atiidyiag 
slnictttre iml ftmction of ^rafihnd eootyttenM an diwiMed end 

iomv uf the findings uifhin ttu ^ iriins irophio levels ate indieetcd. 
Ilic present »Utc of inlcrnalional synthesis within the ^Htand 
Monie it wimiiiiiied. 

INTRODUCTION 

My objective in this paper will be to assess the present state 
of our knowledge concerning structure and function of 
herbaceous ecosystems ran^ig from dry lubhumid to arid 
climates, particularly with respect to the contributions that 
IBP has made to their understanding. A wide variety of eco- 
qntcms is included within the national projects coordlQlted 
lhri)iip,!i the Grassland Workinp, Ciroup unJcr Section PT. 
These arc both tilled and natural, and range Irom wet 
meadows to wmidetert; liiey tut mostly dominated by 
perennial grasses. The Arid Lands Working Group also In- 
cludes, witliin its framework, some studies of semidesert 
and semiarid gnmUnds and extends through the arid shrub* 
by types of ecosystems. Since these working groups have 
been more successful in accumulating results on biological 
productivity in natural ind aeraimtoral tjfttem my preaent 
evaluation uf IBP impact wfll avoid the fflan«impoMd or 
tilled ecosystems. 

Pirlmiiy production has been a basic parameter measured 
in all studies, while other ecosystem processes, such as Sec- 
ondary production and decomposition, have been more 
Umfted. Consequently, this paper emphasizes plant produc- 
tion but includes some iliscussion of tiie roles of consumers 
and decomposers in grassland. According to BazUevich et 



tti (1970), "We now know that the living matter on earth 
is made up dmost entirely of autotrophic, photosynthesizing 
plant organisms, which account for more than 99 percent 
of the total amount." I wonder how much this conclusion 
reflects insufficient knowledge of the abundance of resident* 
in other trophic levds. The total ecosystem studies of some 
gnsdands have revealed living biomass of decomposers and 
consumers in excess of SO percent of that of the primary 
producers (Clarli and Paul. 1970). 

In some IBP projects synthesis is wdl advanced while in 
others it is just beginning. Regular progress reports have 
been prepared for some but nut even all of these are wide^ 
distributed and readily available. Usually only summary in- 
formation is available and for only one or two has final 
analysis and ^nthesis reached the publication stage. At* 
tempts to compare data in international workshops began 
in 1970, but were ineffective until a concerted eltott was 
made io the grassland-tundra workshop held in Port CoOlns 
(Augu5t !<>7?) At this workshop 39 scientists from 

18 countries joined with 23 Americans in an intensive ses- 
sion (international Biological Program, 1972). Interproject 

comparisnns of results were made usine a data hank con- 
taining information from 25 sites in 16 countries. Modeling 
sesdons were devoted to devdopment of simulation models. 

This present report is not a final assessment o'i achieve- 
ments in studies of grasslands and arid lands under IBP. It 
b a progress report and cannot do justice to the vast amy 
of information acquired during the IBP. The working group* 
are arrangiog for international analysis of data and its qrn- 
thesis in puMUied form; fliud evaluation of the impact of 
IBP must await these volumes. Meanwhile, in this prelimi- 
nary account, 1 must draw di^roportionately on informa- 



44 



COj..) I lyi III- J I ; ,a. 



fnooucnviTV of ormsuind kobvitemb 



46 



tkm ooncembig thow itudin diit an better known to ne. 

Although many projecti have converted their results to 
energy values, others have not. Accordin^y, my discussion 
is based on biomass values; biomass is defined as organic 
material, whether living or dead (and wej^ta are of owen> 
dry material including ash). 

PRIIIARY PRODUCTIVITY 

In all grassland studies, biomass (harvest) methods have 
been used to estimate diy matter production, usually on 
an anrnKil basis. In a few, measurements ot rO; exchange 
under canopies have been included. Perhaps in only one or 
two instances have COj gradients (in and above the canopy) 
been a basis of estimation. Biomass techniques quantify the 
rate of production by sorting harvested materials into cate- 
gories at eadi of ae«er«l times in the glowing season. Changet 
in the amounts in the various categories are interpreted in 
terms of production. In some instances aboveground (and 
sometimes underground) parts are divided taxonomicaUy 
into groups with distinctive seasonal growth patterns, while 
in others the principal division is into living and dead ma- 
terial. 

Ml ire success lus been experienced with these methods 
aboveground, since difficulties persist in fmding a satisfac- 
tory basis for distinguishing livhtg from dead structures in 
the soil. It is unfortunate that sampling techniques necessi- 
tate individual estimates of biomass of aboveground and 
belowground parts of the same organisms. The effect of 
translocation on these estimates is nut usually recognized. 

The detailed analyses of plant growth, thai have been 
undertdcen as a meant of estimating the rates of energy 
flow in and out of producers, have given values much 
gieatm than those derived from traditional measurements 
which are designed to estimate only hmmrtable yields. This 
was only partially predictable. WhUe the detailed analysis of 
such workers as Wiegert and Evans (1964) for aboveground 
and of Dahlman and Kucera (1965) for belowground had 
suggested the degree of magnitude by which harvestable 
yield underestimates net biological production, intensifica- 
tion of study under IBP has uncovered a number of factors 
not talcen into account in even these previous Studies. New 
concepts have been developed, especially in respect to 
events that take place during the intervals between shoot 
harvests and that bear on the changes of piant materials 
from one category to another. Recognition of the impor- 
tance of these processes will have a major effect in design- 
ing future studies. 

Shoot Production 

The degree to which pTOilnction estimates are increased by 
species separation ot biomass into taxonomic categories pre- 
sumably is idated to differences In timing of their maxi- 



mum standing crops. It is also expected that the longer and 

more environmentally variable the period (or periods) of 
growth, the greater is the effect of differential q>ecies ac- 
tivity on annual ^ooi production. Estimates of ^oot 
production vary appreciably even if individual species con- 
tributions are considered, e.g., Wiegert and Evans (1964) 
had an increase of 26 percent by this method in Michigan, 
while this yielded only a 10 percent increase in Saskatche* 
wan (Coupland, 1971). 

Even with short intervals between harvests, the extent 
of losses from the green standing crop (and changes from 
dcni standing crop to litter) often has been grossly under* 
csiiiuatod or ignored in "ungra/ed" sites and in control 
areas in "grazing" impact Studies. The very apparent efTect 
of domesticated herbivores on grassland has caused us to 
assume that in protected areas the effect of herbivory is 
nrinlmal and need not be measured. However, in at least 
one study site, the biomass of invertebrates feeding on 
shoots in the "ungra/ed" areas is at least equal (3 to 4 
g/m') to cattle grazfaig on the adjacent range (Mook. 1969; 
Coupland, 1972a). 

Another inadequately evaluated factor in reUUon to 
estimates of aboveground tnet primary production is the 

mode of growth of grass shoots I n-phas:'; nn annual crops 
often has led us to assume that the growth pattern of 
perennia] grass plants is associated with one crop of shoots 
per growing season, at least in areas where environmental 
conditions suitable for growth are of short duration. This 
presumably has justified the use of "hay" yields to com- 
pare producthre capacities of different swards, even as 
pastures. 

Misconceptions on length of growing season have resulted 
in some estimates of shiK)t production which do not allow 
for early and late growth. For example, pre-IBP clipping 
studies in Saskatchewan which were temdnated In S^em* 
ber (Lodge and Campbell, 1971) indicate that 95 percent 
of growth takes place by the time maximum standing crop 
of green shoots is reached. We have since found with studies 
extended into November that 30 to 40 percent of shoot 
production takes place after the period (Coupland, 1973). 
However, evidence from photosynthetic measurements in 
the same site suggest that in Spring and fall gains in above- 
eroMitH hiornassare at the expense of underground reserves 

(Rcdmann, 1973). 

The biomass data available at the 1972 IBP grasabnd 

fMndri! workshop (International Biological Program. 1972) 
give a measure of the range in productivity of the variety 
of herbaceous ecosystems represented. Maximum standing 

crops of green shmtts r.\n9.f from 100 to .''1.000 g/m' witha 
trend of inctea!>cd production with higher mean annual 
temperatures between -2*'C and 26"C. But this is not a 
direct measure of productivity At the workshop we applied 
uniform techniques of estunating annual net aboveground 
primary production by accumulating all gsins in standbig 



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ItT.OOUPUUllO 



crop (detd, as well as green). This procedure had a difrer* 

enlial effcLl in Ihc various environments and resulted in a 
greater Increase of production values over standing crops 
in temperate dintates (Table 1 ). It would appear that the 
values for shoot production will be higher relative to under- 
ground than those previously estimated for the above types 
of ecoayittmf by BizUevkhc/o/. (1970). 

Underground Parts 

Assessment or net primary productivity by biomass methods 

necessitates an estimnte of the net movement of pholosyn- 
lhatcs into underground plant organs. The method mvolves 
wadiuig of soil and plant material througli screens, and re- 
quires recognition of both living and dead p;irts. The re- 
trieved plant material inevitably contains a portion of dead 
roots, rhizomes and tfioot bases which generally has not 
been "ioparaWe from live materials. This problem has been 
addressed at two symposia on root systems during the IBF, 
in the USSR in 1968 (Academy of Sciences of the USSR, 
!%8) and Fast Germany in 1971, but it still remains the 
most limiting factor in obtaining reliable estimates of net 
primary productivity. 

Oalilman and Kucera's (1965) method has probably been 
the one most commonly applied in herbaceous vegetation 
during IBP. It presumes that the difference between maxi- 
mum and tninimum underground plant biomass gives a 
reasonable (but minimal) estimate of plant material devel- 
oped underground during the growing season. Measurements 
made by this nuMns agree with those made by laborious 
sorting of apparently live and dead parts at the same site 
(Kttceia et of. . 1967). This latter method requires a Inge 
number of very time-consuming samplings and many times 
the results do not justify the effort. 

The method of Dahfanan and Kucem does not account 
for losses due to degredation of plant materials during the 
measurement period. For example, in cool temperate gnus- 
lartds it seems reasonable that the period of photosynthate 
translocation underground coincides with the most active 
period for soil microorganisms and detritus feeders; thus, 
the net movement underground can be highly underesti- 



TABLE 1 Annual Shoot (Attoveground) Production Values 
for the Maiof Type* of Herbaceous Ecosystems. Data Taken 
from the Report of the Granland-TundM Worlohop (iMat^ 

national Biological Program, 19721 



Type of Eeoqpilcm 


AbbuI fiodoc 




Itopical and SBbttopkai graid 






■nd nvaniiM 


60(M,«00 




Temperate sUfpe 


600-1.300 




Temperate mcitdow 


700-3,400 






300-SOO 





mated. If losses to consumers are ignored. Thts possibility 

was suggested by results in a study of the tilled version of 
our Canadian grassland system (Coupland, 1972b). To cor- 
rect for the dead organic materUls present at the time of 

seeding of the annual wheat crop, we measured the mass 
of underground organic materials immediately after seeding 
and near maturity (assuming that an increase could be used 

as an estimate of underground biomass additions during 
the 80-day period). The results showed lower values at 
maturity than at seeding suggesting greater organic matter 
losses than gains. 

Biomass methods fail to account satisfactorily for losses 
due to underground plant respiration. During the IBP, there 
luu been considerable interest in using **soi] respimtion" to 
estimate production, particularly in ecosystems that are suf- 
ticienlly stable, i.e., where inputs approximate outputs. In 
the Canadian study. CO; tlow rales from the soil system 
suggest rtial biomass mcliniiis nuv be unJcrcstimalinp the 
amount oi carbohydrate translocated underground by as 

much as SO percent (MacDonaM, 1973). Attempts are being 

made to partition underground respiration between roots 
and decomposers. Several studies have used methyl bromide 
to suppress soil invertebrates so as to estimate die acthdty 
of microorganisms.* Coleman (I'JTO) !kis separated microbe 
and root respiration in the laboratory by comparing the 
activity of separated fractions (roots, litter and soil) with 
that ofintact soil cores. Results of these Studies enable 
only a very generalized apportionment of underftound or- 
ganic matter pools and reqiintoiy activity. 

Traicrs li.ivc boon uscJ :u follow the fluxes of carbon 
after fixation in photosynthesis. Dahlman and Kucera 
(1968) devised a means of labelhig a small plot of grassland 
so that c|uantilaiive sampling of shoots and underground 
organs is possible over a period of several years. By this 
means net rates of chImhi turnover have been estbnated. 
In the Canadian project this approach has been modified 
to provide shortrterm translocation rates of from 
shoot to root to soil atmosphere. Internstlii^y» this ap- 
proach permits monitoring of the '"C content of SoU •!• 
mo^here at various depths, and such measurements 
suggest a much more rapid rate of carbon release from the 
plant than expected- 10 to 15 percent in the first three 
weeks after fixation (Warembourg and Paul, 1973). 

Intersite comparisons of underground biomass at the 
1972 IBP grassland-tundra workshop indicate an increase 
in the ratin of underground parts to green standing shoots 
along ihc laiitudinal-temperaturc gradient from the sub- 
arctic to tropics: the ratio ranges from 2 to IS or more. 
T'lis mot-shoot ratio declined over a similar range along 
a gradient of increasing precipitation tliom l(K) to 2,300 
mm per annum). 

* PerMful coromunicaUon wiUi M. Numata of liie Japanese IBP 
(laaiiBnd fmdjr. 



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pnooucrtviTv of onasslano ECMvsrmc 



47 



SECONDARY PRODUCTIVITY 

Consumption by small herbivores has been assumed to be 
negligible in many previous studies ofgnndand productivity. 
Where biomass methods are used to estimate primary pro- 
ductivity, it is customary to exclude large herbivores from 
control ("ungrazed") areas which then are compared witfi 
"'grazed" areas supporting domesticated iierbivores. How- 
ever, while the activities of large herbivores have been in- 
tensively studied, the biomass consumed by small herbivores 
(grasshoppers, rodents, birds) may be a significant factor. 
Differences between "grazed" and "ungra/ed" areas in 
small herbivore populations may CDiitound measurements 
of the aflect of the managed herbivores. Tor example, a 
preliminary assessment in ihe Canadian study indicates that 
invertebrates may ingest and drop tu litter as much as 80 
percent of the amount consumed by cattle (Coupland. 1972). 
Activities of small subterranean herbivores (espe^ inlly inver- 
tebrates) have been given even less attention, atthougti their 
Uomais may be five to six times that of the cattle supported 
by the system. 

Esliroates of biomass and energy tlow in consumer popu- 
lations are not as refined as those for producers. One major 
difficulty is the lart'e number of species in some groups (e.g., 
invertebrates). Another is the frequent presence of omnivory, 
which complicates distinctJons between primary and second- 
ary consumption, Population studies have, of necessity . 
been of groups (e.g., orders of insects), to which energetic 
values have been applied on the bob of laboratory energy 
buJ^iMs of important species No accurate estimate has been 
made of the reliability of this approach in overall assessment 
of the acthdties of the consumer components of the eco^ 
tcm. Progress appears greater for abovcground than for ttodar- 
ground invertebrates. The subterranean environment is 
eufMt of supporting a host of very smaO invertebittei 
whose interrelationships are only now beginning to be re- 
vealed as a result of intensive investigations in IBP, e.g.. 
nematodes in the Canadian Matador site comprise 60 per- 
cent of the underground invertebtatt biomass (which totals 
4 to 6 gjm} )* while soil zoologists expected arthropods to 
predominate (Zacharuk and Burrage, 1968). 

DECOMPOSITION 

The role of organic matter in the ecosystem is of putioular 
concern in grasslands because of the generally hich content 
of soil humus, particularly in temperate regions. The quan- 
tity of dead organic matter in a grassland system at equJ- 
librhun under steady state conditions depends upon com- 
plex interactions between rates ul prunary production, 
leairiittion, comumption and deoompoiition. We have much 
to leant conoeming Hie iditive activities of cOMunien and 

* Fctsanai coRmHHiicatioa ftom J. It Wilard. 



decomposers in degrading organic material through the 

various stages to soil humus, as well as the functional rela- 
tionstiips of organic matter witiiin the system. Perhaps the 
IBP sthmdated efforts hi total ecosystem modeling will re- 
veal to what extent organic content is important to the 
sustenance of a system and its influence as a storage loca- 
tion for i^ant nutrients. 

The balance between the rates of production and degra- 
dation of plant materials above the soil surface seems to be 
more critical in grasslands in subhumid climates (e.g., the 
forest steppe of southern Russia [Kurs)c| and the portion 
of the True Prairie adjacent to the eastern Jeiidnous forests 
of the USA) than in dry subhumid and scmianJ ones (such 
as the mixed prairie region of North America and Fescue- 
Stipa steppes of the Ukraine and northern Ka/akstan). Un- 
der protection from large herbivores, rapid accumulation 
of furftce litter oocun in subhumid climates to the extent 
tliat repo;)!ed fire is necessary to maintain the existing 
dununani plant species. In the drier regions, however, 
decompoaer organisnM are aUe to deal rapidly with even 
wide annual variations in shoot production; confequenlly» 
less than one year of shoot production is accumulated as 
coarse litter on the surface. 

I'nder IBP we have learned much about the poputafinn 
dynamics and biomass of different groups of soil microbes 
in various grasriand systems. Their abundance Is staggering. 
In temperate grasslands with large herbivores excluded the 
biomass of soil microbes can be as much as 100 tunes itiat 
of the carrying capacity of domcstlcaled anirods (Qarfc 
and I'aul I'^^O Coupland, 1972a). Measuring microor- 
ganism metabolism in the field is very diflicuit. It is not 
immediately obvious how the andhble energy supply sup- 
ports microeirganisms n( k vcls of metabolic activity. While 
rates of CO; (lux from the soil surface are related to 
organic processes withhi the aod, fliere are considenble 
difikulties in partitioning this flux between root respira- 
tion, consumer metabolism and microbial decomposition. 
There are indications that much microbial actWity takes 
place within the rhizosphere, where plant substancetaie 
apparently exuded in quantities greater than generally sup- 
posed. Techniques are being developed in IBP projects, e^., 
(Doxtader, 1970) in rapid chemical determination that 
may provide some answers regarding, decomposer substrates. 
There are indications that much oi the microbial activity 
ocean in spuria associated with certain metabolic events 
optimizing the cycles of nutrient elements in the ecoq^slem 
(Clark and Paul. 1970). 

NUmiENTSUm-Y 

It leams dear that tiie two major Iknitbig factora hi gnaa- 

land production are climate and nutrient supply. The more 
favorable the climate is for growth of grasses, the more 
ciltiealis the au|>ply of nutrients. The natural graatfands 



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aT.oounjiND 



of the world occur in climates where low amounts and 
erratic distribution of precipitation limit the invasion of 
treea from more Inimid and wbhumid regions. Under 
these conditions, one assumes that the amount of soil 
moisture is a more important factor in growth than is soil 
nutifents. It foOows that the drier the area, the less Iflcely 
It is that the supply of soil nutrients will be limiting. These 
are general concepts with which we are all familiar; inter- 
national comparisons between projects will do much to 
sLppuri jr modi: v thete CQilcapts. There are some grass- 
land workers who are more concerned with nutrient supply 
than with moisture supply, probably as a lesuh of nutrient 
dericiencies in the systems with which they are working. 

Nitrogen and phosphorous have received most attentioflt 
probably because it is inevitable tiiat teitilizing practices 
for arabk land would be used to tast responses of natural 

ecosystems. Additionnl nitrogen is usually cffcclivc in 
Stimulating grass growth, and phosphorous mdirecliy in- 
creases the nitrogen supply by stimulating l^umes. Hie 
extent to which nitrogen can be beneficially applied (In 
terms of production) depends on the amount of soil 
motatuie, the raaults being more erratic in arid and aemi- 
aiidtliailiodry, subhumid rctrions. An important mifnut 
of IBF eoOQrStem analyses is expected to be an evaluation 
of the degree to which the nitrogen economy can be al- 
tered without sacrtficing. unduly, the stability of the sys- 
tem. It seems that increased nitrogen supply favors plant 
dombiants characteristic of stages of wccession preceding 
climax and favors the entrance of annual species into the 
natural perennial vegetation cover. In areas where litter 
accumulates on the acHI surface, there is concern that the 
amount of nutrients taken temporarily nut of circulation 
will limit the productivity of the system. This implies that 
it might be desirable to speed up the rate of cycling of 
these nutrients. Analyses using models should provide a 
better comparative measure of aitemitive ways to achieve 
titls. i.e., by increasing the rate of use by eonsuman or by 
stimulating decomposition through fertilization. 

Under IBP, nutrient budgets have receWed considerable 
attantioa. We are beginning to understand better the rela- 
tiOtHhips between available and nonavailable forms of 
various nutrients, the magnitudes of nutrient "sinks", and 
the nutrient release rates from these sinks. In many in- 
stances. It seems that the rate of exchange from unavailable 
to available forms affects the vigor of plant Krowth Perhaps 
the major contributions in this area have been consideration 
of nutrient cycles under a wide variety of giaadand oondi- 
tions. Studies of nitropen fixation have apparently provided 
much new information on inputs of nitrogen into grassland 
ecosystems and have stimulated the search for other sources 
of origin, fixation and Internal conversion. For example, the 
organisms re^nsible for asymbiotic nitrogen fixation have 
been Identiflad and lh« Inteailty of ttieir activity in natural 
gnsriandt has been found to add 1 toSUkgramsof nitro- 



gen per hectare per year (Paul ci al. , 1971 )■ Rainfall supplies 
approximately twice the amount provided by asymbiotic 
microorganisms. These inputs are rather insignificant in 
comparison with the nitrogen fixed symbiotically where 
legimies are abundant in grasslands. Grassland ecoiystenu 
witii a low natural input of nitrogen, but with a hi^ com- 
ponant of stored nitrogen in organic matter, can be in- 
creased in productivity by processes that increase the rate 
of brealtdown of organic matter. We must be careful not 
to exploit organic reserves in these ecosyatams without 
taking into consideration the long-term consequences of 
these actions on site fertility. Are we sure that artificial 
applications of nitrogen later will companaala fully for the 
loss of organic mattef? 

CONCLUSION 

IBP Studies in herbaceous ecosystems from subhumid to 
arid climates are iwwaling complex trophic stsuetma and 

a diversity of factors that determine capacity for bio- 
logical productivity. Many new principles will evolve during 
the ansJjrais and synthesis of the vast amounts of data 
from projects, .ind comparison of parameters across re- 
gional and geographical scales. Data sharing has been ac- 
cepted by investigators and makes possible the future 
development of simulation models of wide application 
to resource management. A very sound basis has been 
devdoped for planning and executing of giasriand studies 
under UNESCO's Man and the Biosphere program that 
wiU provide a background for management of grassland at 
a suttainabla leva! of ]»roduetion. 

REFERENCES 

Academy of Sciences of the USSR. 1968. Methods of itudiw of 
productivity of root systems and rhizosphete oiganlatos. Pro- 
c«c<iin|.''^ Ill' :i 'sympiisiurn h>:ld al Moscow, Lsuiapail aad 
Dushambc, August 28-Septemb«r 12, 1968. 

BiSllevich, N. I., L. E. Rodin, and N. N. Romv. 1970. GeograpM- 
«al aspects of biokiiicil pioductiiiiiy. Papers of the FtfUi Con- 
gmt of tte BMcgiad Sodsir, LmiapBd, USHL 2t p. (IfciH- 
tatcd in Soviet Geognpliy: Kevtew inTtaailstlenfc Uw 1971. 

p. 219-317). 

Clark, F. K., and V A P^iul. 1970. The miciqilow »f ^ajiiid. 
Advances in Agronomy 22:375-435. 

Coteman, D. C. 1970. A compartmcnlal analysU of total soil respi- 
ration, p. 1 26-1 28. In R. T. Coupland and G. M. Van Dyne (ed.) 
Grassland Kcosystems: Review of Research. RaRgS ScL Dlp^ ScL 
Set. No. 1. Golonulo Stale Uatvenity. 208 p. 

Coupland, It T. 1 TTt Itiiiiiiaii mnmii nainiili tn nitiiis giailsiid. 
p. 19-33 In Fourth Annual Report of the MaUdor flM(|SCL 
University of .Saskatchewan, Saskatoon. Canada. 

Coopland, R, T. 1972a. OpeMlKui.il ph;iM- ( l<Jh7-iy72): A sum- 
mary of progress. Technical Report No. 1, Matador Project, 
University of Saskatchewan, Saskatoon, Canada. 

Coupland. R. T. 1972b. Bkmuia meaaamnaali in wiutUand, 
p. 2S-26./II PUdi AmhI Rapoft of (he Ifalador hi4sct Unf- 



Copyrighted material 



raoDuenvffv op ohahuno loomreM 



49 



GoMplnd. R. T. 1973. Hat Momui praAKliiM. n-91. Ar 
Meuorement and ModcUiqg of Fhotosyntheilt ta Rchtkn to 
Prodnctivity. Proceedmp of the CXTIBP/PP-Pi Workihop at the 

Univenity of Guelph, Dtccmber 8 to 10, 1972. 
Dahlman. R. C, and C. L. Kuceia. 196S. Root productivity and 

turnover in native praiiie. Ecology 46:84-89. 
fMUinia, R. C, ud C. L. Kuceia. 1968. Tatfiiw utiw gnailaiid 

««*latiM «Mi aibM-14. EMc«r 49:1199-im 
Dmtader. K. G. 1970. BlonMi dBlmteliaii of nl aienoii^ 

oinna. p. 107-lOB. /it R. T. Cottptind md G. M. Van Dym 

((WL)Granland Ecosystemv Reviews of Res«jn.li RingeScL 

Dept Sci. Sci. No. 7. Coloiaiia Stale University, 208 p. 
Inlernational Biological Program, PT Section. Grassland and Tundra 

Workintt Groupt. 1972. Rqiort of the modelling and synthesis 

workshop held at the Natural Resource Ecology Laboratory, 

Colorado Stat* Uaivenity, USA, Aufusi 14 to 26. 1972. 
KiMOfiu C. U IL C MdiMt^ and It R. ItodHiv. IM7. Total wt 

productivity and turnovac on an OMiir fcaili Car taQpaia piaMa. 

Ecoloey 48:S36-S4I. 
IxKjgc, R. W,. and J, h Campbell, 1971 Mjnii);cmciil oT tiMWaaian 

range. Canada Dept. of Agriculture, Publication 1425. 
MacDonald. K. B. 1973. Modelling soU teipiration, p. 20S-211./ji 

Measiuenmit and Modalling of RMtotyikliittitiii Ralation to 



ftoAKlMly. PncaadinKt of Hi* oaBr/PHi Wortttfiop at lha 

IMvanity of Guelph, December 8 to 10, 1972. 
liook, L. J. 1969. Surface Invertebrates, p. 45-52. Jn Secortd Annual 

Report of the Maudor Profocl IM«aiiit|r of SarialdiawaB, 

Saskatoon, Canada. 
Paul, E. A., R. J. K. Myers, and W. A. Rice. 1971. Nitrogen fixation 

in giaiilaad and anociaiMi cultivatad acotyticau, p. 495-507. 

/« nant aa4 SolL Spedal VabMN* o« Motaiilai NkratM Ftea* 

tioii In Natnal aid Asfiniltual HVUMl 
Radmann, R. E. 1973. Carbon dioxide antaidalioa nuMlei, p. 187- 

193. /» Measurement and Modelling' of Photinyntlicsis in Rela- 
tion to Productivity. PmnrL-dings ul ihL- C C lUl'/PP I's Workshop 

at the Uiiin'rMty of (;u<'li>h. December 8 U> 10, 1972. 
RteawbourK, K. I .. and t. A. Paul. 1973. llic useof C'^Oj c«nopy 

jadiniqiHa for measuring carbon transfer tliromh Hio piaat- 

aol tfHan. Plant and Soil 38(2):331-34S. 
Whiert, R. C. and P. C Evan. 1964. FMaaiy ptodMctleii and Iba 

dinppcarance of dead vegeution on aa oM fWd in aoillNaalam 

MAigan. Ecology 45:49-63. 
Zacharuk, R. Y , and R. H. Burrage. 1968. Subsurr.ur invertebrates, 

p. 38-41. In First Annual Report of Uie Maudor Project, Uni- 

vanity of SarfatclNwan, aaritatoon,Cmada. 



Copyrighted fnaterial 



THE IMPORTANCE OF 
DIFFERENT ENERGY 
SOURCES IN FRESHWATER 
ECOSYSTEMS 



K. W. CUMMINS 



INTRODUCTION 

Despite « shift rMulting from flic wtivitiei of induitrialized 
man, photosyntheiis and respiration (Machta. 1 07 1 ) gen- 
enlly balance in the biosphere. Some ecosystems, or com- 
partments of ecoiyttenn, depending upon the aomewhat 

arbitrary conceptualization of system dimensions, are 
known to be autotrophic, i.e., producing reduced carbon 
compounds in excen of (he amount that is respired. It 

follows that other compartments or ecos>'stenis are lictero- 
trophic, with oxygen consumption exceeding photosyn- 
thetic oxygen production, i.e., soil oommunitles, aphotic 
•quatic subsystems and woodland streams. 

Autotrophic communities are characterized by a ratio 
of photusyntheais to respiration greater than 1 (P : R > 1) 
(Odum, 19S6)with the oxlcss production exported to 
tieterotrophic compartments or systems. For heterotrophic 
oommunities P : R is less than 1 (P : R < I ). Clearly systems 
in which P : R ■ 1 mutt be combinations of autotrophic 
and heterotrophic compartments. Fisher f I')?!) (Fisher and 
Likens, 1972) suggested a modiHcation of the P : R expres- 
sion such that: 

where / " input; E ■ export; AS = annual change in orsanic* 

matter standing crop. Of course, if / = F and A5 = O over 
the annual cycle, as may often be the case in streams, the 
P : R ^atem is Tilid as previously used. 

50 



GENERALIZATIONS ABOUT AQUATIC ECOSYSTEM 
ENERGETICS 

Recently it has become clenr that striking analogies are to 
be found between terrestrial soil communities, lenUc benthic 
communities (hydrosofls) and runnbig water systems in 
general. Excluding large rivers, particularly when extensive 
impoundment has occurred along the drainage, running 
waters resemble terrestrial sod eommtmities, since the 

above-sediment portion supports little primary prLiJui:tit vii 
constituting essentially a transport system. Analogies be- 
tween lentic (standing water) and lotic (running water) eco- 
systems are clear only when certain system compartments 
are considered. Because lentic environments have previoudy 
teoeived the majority of attention by t teslnvster scientists, 
running waters have been empliaslzed in the present dis- 
cussion. 

Lentic Systems 

Energy inputs, i.e., light, and photosynlhetically initiated 
organic matter from the terrestrial survoundings, and func- 
tionally compartmentalized biomass. are shown tn highly 
simphfied form in Figure 1. Both the terrestrial supply 
vstem. and the littocal and planktonic compirtments of 
standing waters produce organic matter in excess, that is, 
P : R > 1 . This excess of reduced carbon compounds frcnn 
the landKipe, from phytoplankton and from vascular 



Copyr^hted material 



THE IMPORTANCE OF DIFFERENT ENERGY SOURCES IN FRESHWATER ECOSYSTEMS 



51 




FIOURE1 A gligllll rt wpw m WiBDii vf UM t t wi yi— i ftwidnil o— ipi fWiMiUl hi llDi i . iii p lii* It an <w pmamdnt of nf|y l ipuii 



hydrophytes (plus epiphytes) feeds" the benthic com- 
monity-a compartment characterized by P : R < I. 

As in ahovcground terrestrial communities, the ma- 
jority ot the biomass resulting from photosynthesis 
(planktonic algae and vaacuto hydrophytes and asiociated 
cpiphyton) is not processed by grazing animals. Upwards 
of ^0 to 90 percent of lentic primary production enters 
the benthic tyitem without passing through grazen (for 
a current treatment and review of detrital processes in 
lakes see Saunders. 1 972a). Many, if not all, lentic grazers 
are actually detritivore-h«rfoivoi«t with food habits re> 
strit ted by particle size and food texture rather than the 
presence or absence of functional chJorophyll (Curoinins, 
1973). Planktonic gnaers are at least as dependent upon 
particulate detritus(andtheanociatedmierofloia)as 
upon living algae. 



LotieSyttamt 

The generat pattern by which organic matter is made 
available to, and processed by, the communities of 
stream ecoqfstems oT tempente<Eone woodlands is now 
fairly clear (Cummins, 1 972a; Fisher and Likens, 1972) 
although many cntical details (particularly rates) remain 
to be delineated. As shown in hii^ily simplified form in 
Figure 2. the energy supply for streams, «milar to lakes, 
can be partitioned into two general components: the input 
of particutate and disaohred organic matter of terrestrial 
origin, and in-stream photos> nthetic carbon fixation. In 
ruimiog waters the former is generally quantitatively much 
greater. 

Tlie pool of large particulate organic matter (approxi- 
mately > 1 mm) is maintained primarily by the terrestrial 



Cc( , i i J i;ed material 




FIGURE 2 A iimplifiad rapraMntatiofi of tfi* tuftctiotial camp«rtin«ntaiiution at a lotic •eoayttMii. Emphsli li on liw proc m t n g of aMrfy 
11 1 — w w wli M of|Mil»iiiimrwii>liyt»iiriiMwiliiiAflwC > HWWli Mi ,l^^ 



Input of vBKuttr plant tinue, e^., leaves, bud acalcs, flowen. 

fruits, baik, twigs, branches and large materia! such n<; logy 
which are subject to veiy slow processing and, therefore, 
hava long ratidenea times. An important feature of ctreams 
is their function as concentrators of this material, since 
they act as "sticky uaps" (H. B. N. Hynes, University of 
Waterloo, penonal communication). As in the lentic lya- 
Icms, ifvascular hydrophytes are present (e.g., watercress) 
they tend to enter the processing cycle primarily as if they 
ware of terraitiial origin nthar than through the grazing 
activities of stream herbivorea. The pool of fine particulate 
matter (approximately < 1 mni) is derived from in-stream 
processing of large particles (e.g., fragments brolcen loose 
tfirou^ animal activities or physical abrasion by sediments 
in transport, and animal feces), from algal cells sloughed 
from surfaces, from tfie microorganisms always aHOciated 



with fina oiganic partkka, and from the physicaMiemical 

flocculation of dissolved organic? Other fine particles of 
terrestrial origin, such as feces of insects feeding in the 
foieat canopy, are also part of Ms pool and may be quan- 

titativcly very tmportanl during the summer. The dis- 
solved organic pool is replenished from the leaching of 
tarraitfial particulate orguiics, eithar beibre entry (runoff) 
or after the particulates are in the stream, and from algal 
(plus microbial and animal) excretions. Leaching of leaf 
litter it rapid (essentially complete 24 hoois after the litter 
is wetted) and quantitatively significant (5 to 40 percent of 
the dry weight of the litter) (Cummins et oL, 1972; Peter- 
len and Cummins, in press). 

Leached vascular-plant tissue represents an organic sub- 
strate composed of "resistant" carbon compounds (about 
half cellulose) and little nitrogen. Although propagules of 



Copyriyliicu iiiator 



TMC IMPORTANCE OF DIFFERENT ENERGY SOURCES IN FRESHWATER ECOSYSTEMS 



S3 



ternttiial fungi and bacteria are present on the litter before 
it eaten the water, rapid colonization and growth by 
aquatic forms (e.g., aquatic hyphomycetes and gram-negative 
bacterial rods) dominate in the stream. The metabolism uf 
these microorganisms is characterized by cellulose degrada- 
tion and nitrogen uptake fram the water. The presence of 
the associated microflora converts the litter to a suitable 
food source for animal metabolism (especially through in- 
crease in protein). Labile organics in the leachate are un- 
doubtedly rapidly taken up by microorganisms associated 
with the sediments and organic particles, as well as those 
in transport (Cummins oil, 1972). 

Soon after, and probably in response to. microbial In- 
festation of the large particulate organic matter such as 
leaf litter, laigB ftartide detrithNMes (''ihfedden*') move 
into accumulations of such material and begin feeding A 
variety of experiments have shown liiat stream detritivores 
sdecthrety feed upon the detrltiu maximally colonized with 
microorpnisms, particularly fungi (Triska, 1970; Kostalos. 
1971; Macluy, 1972). The general effect of shredder feeding 
b to reduce the average particle size, thereby providing addi- 
tional fulwlrate wrftoe for mieraUal (opedally bacterid) 



colonization and metabolism, and food for fine ptrtide 
detritivores CcotlectoTa'O (Cummins, 1973; Cumminf er . 
1973). 

Primary production, usually minimal in woodland strenni* 
is dominated by diatoms which are diade-adapted and may 
function as facultative heterotrophs. Correspondingly, the 
grazer species feeding on the periphyton are characteristically 
few, and often dependent on the intake uf signiticant 
amounts of Tme particle detritus which accumulates in the 
interstices of the periphyton cover (e.g., Cummins, 1973), 

Populations of collectors and grazers are reduced by 
atfeam |»ndaton<both invertebrate and veitebrate) throii||i> 
out the growing portion of their generations, while the 
shredders are subject to significant predator mortahty in 
the early part of the growth period. 

The bodies of animals, dyitip otherwise than by prcda- 
tion, animal exuviae and feces qujcicly enter the fme particle 
pool. The convenioa of reduced cwbon oonqraonda toCOs 

is efficient, being at least 8(y?f of particulate and 50% of 
dissolved materials on an annual basis and, strilungly. a 
dgnificant portion ii acoompUdiad at temperaturai below 
IO*C.TIili iiin ihaipoontrait to tamatiial and, inually. 



Braxxu. nocnsnc hobs 



nn MmcDiAiB 

I€ 



laeteatcial 



VMealar 



wnc 

Tieeaeettal 
nrlft 



URIC 



oaazDB iMcnanB 



tone 



tmc 



pMlei 



Utteisl 



STUMS 

t 

mx 



PnTURBI^TIOIB AID 



Sarceaertal 



Drift 
mad 
MMraal 



I liCCeval, 
iTatfWCrlat 



I 



(Brift) 



Veela 
liffUa 



EnClia 
BMta 



FIGURE 3 A limplifM Mmmary of aiMfyy rniniti «e twilMiiiiMr tyttMiw. Tha cfltumns tn arrwe**' 
liinrMing moitat (and particl* srza) md lotic or lanlie ■ y i twi n . TIm horiiontil organUatlen of the flguf* i« 
Um tytttm or tl^>< Ik.h ii iii n ilie tystem of th« erMrgy lupply. A tramition 'n indieand 
Inatpiitiontly parturbatad iyatami. to Mm loMMr. "matura" and/or iMnurtaMad ■yMMtt. 



to 

at Mw prim a ry ! 



Copy lighted material 



54 



K. W. CUMMINS 



Standing water systems of the temperate zone (.CummiiKM 
of.. 1972). 

COMPARISONS OF SYSTEM ENERGETICS 

Lotk and lenlic s;, stems have been compared, according to 
the processing of energy, inputs, in Figure 3. Detrital and 
grazing processing functions aie compared, with lotic sys- 
tems dominated by the former and lentic systems domi- 
nated by the latter. The primaiy origin or localization of 
the energy source of a lotic or lentic system operating 
predominantly in either a detrital or grazing processing 
mode is given along the luni/ontnl of Figure 3. Changes 
inihedomlnaneeof inpu[:> jmO pr^xc^^^ng mode relative 
to HZ8 of Stream or river and depth of lake or pond are 
compared from the upper to lower portion of the figure. 
As indicated, these differences may result from natural 
"aging" (thai ts, "young"" head water streams and deep 
and/or clear lakes tn "olii"" hnver drainage rivers and slial- 
low lakes and ponds) or acceicrated "aging"', i.e., man- 
engendered perturbations. "Fxternal" energy sources 
(lower half of Figure 3) refer to inputs of reduced earhon 
compounds resulting from hiunan-related accumulations 
(urban, agricultural and industrial) as oppoied to normal 
inputs from the drainage. 

Through "aging", natural or accelerated, lentic systems 
diift to Increased dominance of the detrital proeesiing 
mode. In contract, (he typical sequence for streams would 
l>e a sitift from dominance of the detrital processing mode 
through a grazing mode to a second detrital-bosed ^stem. 
The intermediate step invnivcs increases in filamentous 
algal forms and, often, m vascular hydrophytes. This stage 
is acoderated in proportion to increasing light and nitrate- 
phosphate inputs. Much of the animal, and probably mi- 
crobial, diversity is lost and increasing organic inputs, 
leadbig to the second detrital phase, are processed with 
comparative inefficiency (Cummins, 1972a, 197 2h). The 
latter detrital-based system operates in the absence of 
most of the community structure important in the natural 
initial detriial phase. This is particularly true of titat por- 
tion of the biota which in nonperiurbed streams utilizes 
the large particulate organic matter, such as leaf litter, snxe 
human-related inputs are usually characterized by efflu- 
ents high in fine particulate and dissolved organic matter. 

It seems dear that quantitative assessment of detrital 
and pihotOQrnthetic inputs to running and standutg water 
ecosystems, viewed as processors of reduced carbon 
molecules, is a fruitful approach-both for the basic under- 
standing of freshwater ecosystem structure and function, 
and as a sensitive monitor of "natural" and accelerated 
system changes. It should be particularly fruitful to con- 
trast detritus processing modes In lotte and lenlic systems 
(Figure 3) especially community respiration associated 
with detiitus particles. The relationships between re^ira- 



tion, particle size and the qualitative nature (e.g., cellulose, 
lignin, chitin. etc.. content) of detritus, when viewed in 

reference to community pholosynthrsis, should provide 
new and uselul insights in P : R comparisons (Hargrave, 
1972: Petersen and Cummhis, hi press). 

REFERENCES 

Cumminii, K. W. 1972a. Predicting variatiom in energy flow Uiroujch 

a semi-controlled lotic ecosystem. lUek. Slate IMv. last. Water 

Res. Tech. Rep. 19:1-21. 
QnuahH, K. W. 1 972b. What ii a ri«ci7-molcKical doctlpliMi. 

p. 33-92. /Ji R. T. Ogifliby, C. A. OuiMM, aa4 1. A. MtCm (ed.) 

Rhwr ecology and man. Academie Pms. New Yorlt. 4tS p. 
Cummins, K w. 1973. Trophic lelalieMor aquatic imectti AuL 

Rev. I nt. 18;IR3-3n6. 
Cummins. K. W., J J klug. R G. Wetzel. R. C. Petersen. K V. 

Subcrktopp, B. A. Munny, J, C. Wuyeheck, and F. O. Howaid. 

1972. Orsanic enrichment with leaf leachate la espcdnnntal 

lotic eco^ems. BioScL 22(12):719-722. 
Omimin*, K. W., R. C. Hurnn. P. O. fhmui, I. C ftaydieck. 

and V. I. Holt. 1973. The uiQtzaUoaorieariitlwIqrsiMem 

detrilivorcs. I-col. 54:336-345. 
Fisher, S. G. 1971 . Annual energy budget of a tmjll io:e-.i vtrcim 

ecosystem. Beat Brook, West Thornton, New Hampshire. Ph.D. 

disserlJtian, Dartmouth Cullq:e. 97 p. (UnpiillL) 
Filher. S. C, and G. E. Likens, 1972. Siieara ecaqrslBBi: oqanlc 

eacrgy budget. BtoSei. 22(1 ):33-35. 
Hargmve, B. T. 1972. Aerobic deeompadtkm of asdiment and 

detritus as ■ fbnclion of particle surface area and oifsnie 

content. I.irnnul, Oceiino^t, 17:583-596. 
Kostalus. M. 1971. A study oi the detritus pathway: the role of 

du'tritus ;<nd the .issociated mictobiota in the nutrition of 

(Jamarus muius Say (Amphip(xla:GamilMridae). Ph.D. disaerta- 

tion, Univ. of Pittsburgh. 1 52 p. 
Machta^L. 1971. The role of the oeceas and blo^heie to carbon 

dioxide cycle, p. 1 21-14S. tn D. Dynsen and D. Jaf ner (ed.) 

The Changing Chemistry of the Oceans. Proceedings of the 

Twentieth Nobel Symposium, 16-20 August 1971. Aspcnjs- 

patdon, Lcrum and Chalmers Univ. of Technology. Golcborg, 

Sweden. John Wiley & Sons, Inc.. New York, t.undon, Sydney. 

365 p. 

Mackay. R. J. 1972. The life cycle and ecology of />cnqpQwbe 
giewfjMr (tteljWai), A tenfmre (Beltca), and tethripumlt 
(Rambur). (TridioptsiBiUnmspliilidae) in Hfsit CM. Mont 
St. HUaire. Quebec. l>h.D. dlsBarlBtl«|«llicGUIIteiir. 103 p. 

Odum, H T 1956. Primary piodactien la flowing watenpLtanmL 

Oaaiiott 1:102-117. 
Petersen. R. C. and K. W. Cummins. In preaa. Leaf pffOCHiiBgiBa 

woodland stream. I reshwatet Biol. 4. 
Saunders. G. W. 1972a. The transfoimatloii of aitificiil detiitus la 

lake water, p. 262-2S8. in U. Itelchion^taliai and J. W. 

Hopton (ed.) Proceedings of Detritus and In Role in Aquatic 

Ecosyslc-ms. IBP-UNtSCO Symp. Pallanza, 1971 VU-morie 

Deir Islitulo Iloliano Di Idrobiologia. Vol. 29 SuppI 1972. 

540 p. 

Saunders, G. W. 1972b. Summary of the general conclusions ot the 
lympotiiun, p. 533-540. In V. Mclchiorri-Santolini and J. W. 
Hoptoa (ed.) Proceedings of Detritus and Its Role ia Aquatic 
Boowslenu. IBMJNBSCO^mp. Mlama. 1972. Memoiie DdT 
(itituto llaliano Di Idrobiologia. Vol. 29 SuppI. 1972. $40 p. 

Triska. F. J. 1970. Seasonal distribution of aquatic hyphomyeeies 

in relation to the disappearance of leaf liticr tr im a woodland 

itteam. Ph.D. disserution, Univ, of Pittsburgh. 162 p. 



Copyrighted material 



TERRESTRIAL 
DECOMPOSITION 



DENNIS PARKINSON 



ABSTRACT 

The importance of the decomposition of otgiinic mallei in the mam- 
uamoe of wl fmilUy hn been long known. However, moe the 
oonccfM of otguk matter deoompodticMi at merdy the dwmkal 
oxidetioB of orpmic compomdi pve way to a more dynamic 

biotu^ical interprelalion, accurate, coordinated data on the inter- 
actions of toil microflora and fauna in (his complex procctt have, 
for various rcasuns, been long delayed. This present ciinlnbution 
doe* noi aim to ic%'iew comprehensively the subject of decompoti- 
lion of oiysnic nutur hi tnmtrial envtaonments. lather it aimi 
to pofau OHt the pnUemtflflooiinlerad is audi itudiM. 

INTRODUCTION 

Over several decades agricultural and forestry studies have 
yielded much data on organic matter decomposition under 

specific cultural conditions and frotn which schema, such 
as that given by Paul (1970), have been built up. A variety 
<rf orgulie inattriib Wive at aubitfalet for mlciobiil growth 
and energy production (Paul, 1970, has reviewed the field 
of plant components and soil organic matter). The metabolic 
versatility, widi respect to ability to degrade a wide range 
of organic compounds, of the bacterin and fund led to the 
almost tacit assumption that soil contained microorganisms 
capable of adapting to the addition of any compoond: 
however. Alcx.indcr in reviewing this concept 

points out that various compounds have chemical proper- 
ties which render them difficult to degrade, thus the con- 
ccpt of microbial infallibility must be modified. Wliilc 
much attention, in this regard, has centered on the degrada- 
tion of herbicides, etc., it riiould be remembered that tiw 
humus complex is a natural example of thta type of sub- 
stance. 

66 



Despite the work on earthworms, and on animal activi- 
ties In mull and mor forest soils, little attention was given 
to the role of soil fauna in orpnic matter degradation in 
applied ecological investiptions. However, the inception 
of integrated ecological studies under the IBP/PT has al- 
lowed the development of studies on organic matter decom- 
position and of detailed studies on the soil organisms 
involved (and the interactions between these orgaitisms). 
These IBP/PT studies are demonstrating that the decomposer 
cycle, with accompanyine nutrient cycling is one of the 
great driving forces of ecosystems ol greater importance 
thaiimanyecologisls hitherto appear to have realized. 

INAIN FACTORS AFFECTING DECOMPOSiTiCIN 

As a result of many of the IBP/PT studies, variotis factors 
have been defined as important in affecting either the 
potenlisl or tlie obaeived rates of decomposition: diemlcal 

qualities of the organic matter, temperature, moisture con- 
tent, available decomposer organisms, being the factors 
whidi have received most consideration. 

Cfiemical QuaUty 

Plant and animal debris provide complex mixtures of or* 
ganic materials whkh serve as substrates for biological 
activity and therefore decomposition. For nuny studies, 
detailed chemical analyses of such materials are lacking; 
therefore detailed studies on the rates of disappearance of 
faidivldual compounds have not been followed. One excep- 
tion to this generalization is the case of cellulose decompo- 
sition, detailed studies on which are being followed in all 



Copyrighted material 



66 



DENNIS ftAnKINKM 



IBP biomes. Pacton such as high pulyphcnd and tmnbi 
content, high content of soluble carbohydtatN, high lignin 
content, etc.. are known to affect the time course and the 
by-products of decomposition. Local concentrations of 
inorganic iwtrients and trace elements alter the activities 
of decompojer organisms (e.g., the importance of nitrogen 
content in aliccting rates of cellulose degradation). 

T6mp6fiiiira 

This is a weO-known controlltaig factor for Woiogiea] fmv 

cesses and. therefore, acts as a control of the rate of organic 
matter decomposition. For organic matter in the litter layer 
(at the soil surface) hi open situations, marked dhimai and 
annual Huctuations in temperature may ixcur; these fluctua- 
tions can occur independent of air and soil temperatures 
(because of radiation fluxes, etc.). For organic matter incor- 
porated in the mineral soil (e.g., in the rooting zone) such 
short-term temperature tluctuations are not seen; however, 
fteedng-thawing cydes in soil vstems are known to be 
important in the tdease of nutrients ffom soU organic 
matter. 

MoMura 

Moisture content has been shown to be of great hnportance 

in controlling biological activity in litter and soil. The effects 
of extreme moisture conditions on the rates and products 
of decomposition ate well known (thus waterlogging causes 
changes in pH, redox potential and oxygen concentration- 
all of which affect the pattern of decomposition). Desicca- 
tion and remolstening of soO affects nutrient release from 
soil organic matter. 

In IBP/PT projects a good deal of detailed data on the 
controlling effects of temperature and moisture are being 
accumulated from field studies. However, it is necessary 
that these studies should be accompanied by experiments 
on decomposition rates under controlled environment con- 
dttlomsin order tlut dwialalive roles of temperature and 
moisture availability as controlling factors in dfcnmpositioo 
can be more precisely defined. This type ol study is of 
particular importance in studies of decomposer activity bi 
more rigorous climatic zones, e.g.. tundra, where human 
activity and colonization is increasing, with a consequent 
addition of organic materiais (natural and "ttlnrnT^ to the 
ecosystem. Obviously a detailed study on the dyiMUnkS of 
organic matter decomposition is necessary. 

AtnlliMa OfgMisma 

Prior to the tBffn projects there were very few compre- 
hensive studies on siiil orpimisnis in natural communities 
(notable exception being the New Zealand Soil Bureau 
work on tussock grassland toils). Now, for most terrestrial 



biomes, detailed and mt^ralsd soil biological data m 
beiog obtained. Thus, infomMtion on species present (and 

their frequency of occurrence), biomass and (where possi- 
ble) the rates of growth and metabolic activity of theae 
species is being obtained. 

One of the features of these studies has been the emer- 
gence of the fungi as. presumptively, the major group of 
decomposer organisms, hlowever, this comment must be 
tempered with the knowledge thai methodology for the 
study ot soil fungi and. in particular with respect to the 
estimation of amounts of Uve hyphae, h, to say the least, 
imperfect. 

For both soil bacteria and fungi there is still a lack of 
knowledge on rates of turnover of populations, and on the 

physiolfieica! aclivjties of individual groups. Inferences on 
the latter problem can be made from pure culture studio 
on Indhridual species, however, such inferences must be 
made with care (Harley. 1971). 

The view that the principal roles of the soil fauiu is to 
predispose (throu^ fragmentation) the organic matter 

to microbial attack and to act as agents of spread o( soil 
microorganisms, is well known and is being reconfirmed 
hi soil studies in IBP. 

METHODOLOGY 

In the various IBP/PT studies, a variety of methods of vary- 
ing sopliistication, have been applied to assess rates of 
organic matter decomposition. In most biomes there does 
not appear to have been any attempts at standardizing such 
methods-the tundra biome being an exception. Howevei, 
In most sites field studies on rate of dry weight loss studies 
have been carried out using litter samples (leaves, stems 
or roots) as have similar studies using pure substrates (with 
cellulose the prime example of this type of substance). In 
these studies, the substrates being studied are held in nylon 
mesh bags and placed on the litter surface and also at differ- 
ent depths in the litter and soil. In a restricted number of 
national projects field studies of the type mentioned alxive 
are being accompanied by similar studies in litter and soil 
samples held, in the laboratory, under a range of coiutant 
(and dafbiad) environment conditions (eg., tampeiature, 
nutrient status, moisture) Reference has been made CilUer 
to the need for more studies of this type. 

Soil and litter respbation in both field and laboratoty 
situations has been used as a basis for decomposer cycle 
studies (Macfadyen, 1971) and for study of the effects of 
envlronmeatal conditions on rates of decomposition (pa^ 
ticiilarly of specific substrates), laboratory experiments, 
using a variety of micro- or macrorespirometers, on soil and 
Utter respiration and on tfw effects of sod amendmenia 

(ujin^; pure or "T^atural" substrates), can give a measure of 
potential decomposer activity and can indicate the effects 
of such environmental vaiiablcs as tempetatnn, motatnie, 



Copyrighted material 



TERRESTRIAL DECOMPOSITION 



57 



etc., on the decoinpoaition rate. However, nich methods 
litve been frequendy crftidzed becnue of the gron distur- 
bance uf the system and the artiflcial conditions under 
which the experiments are usually carried out. Field mea- 
surement of soil and litter respiration has been discussed 
bylliebi^(1971)and Parkinson et ai (1971). where 
problems are encountered because of the imprecision of 
calculation of the amount of respiring material being mea- 
sured and because of the role of living roots in the recofded 
respiration }!"pctijlly, as a result of IBP/PT studies, more 
data will be available to allow better assessment of these 
fleMttttdies. 

More iwecbe data on the degradation of pure substrates 
may be obtafaied using radiorespirometry, \Jt^ '^COj evo- 
lutioo from **C4ibeled aubitntes. Maywdon (1971) his 

reviewed these methods. Edwards et al. (1970) discuss the 
values of labelling (with radioisotopes) organic debris in 
onter to meaaure iois of elements during decomposition 
and there are numerous examples of use of isotopes in 
studying nutrient cycling in natural ecosystems. 

SOME PROBLEMS IN TERRESTRIAL DEOOMrasmON 

STtioies 

One of the major group of problems facing the snil biologist 
studying organic matter decomposition is that of the heter- 
ogeneity of the environment, flie heterogeneity of the de- 
composable substrates entering the system, and the hetero- 
geneity (in nature and distribution) of the decomposer 
orgmiann. 

To allow for most efficient study, decomposition sites 
such as pure stands of conifers with no associated plant 
^ecies, »e imich pfefenUe to (he complex angiosperm 
population structure of mixed deciduous woodland (where 
a bewildering array of materials are presented to the decom- 
poser organisnis). However, even in the former example 
wiiere the Htter input appears very uniform in quality and 
quantity, it must be appreciated that this litter represents 
a complex mixture of substrates for microbial colonization 
and exploration, and a complex environment for soil fauna- 
macroflora interactions Also differences in physinldirical- 
biochemical condition l^etween individuals of the same 
Utter produelngspecieswia cause differences in the diemi> 
cal quality in the organic matter entering the decomposer 
system. Another lactor contributing to "substrate hetero- 
geneity** is the time of the year at which the material lie- 
comes available for decomposition-changes in chemical and 
physical quality of plant parts at different times in the 
frowing ttason are being followed in various IBP/H* pra)ects, 
and these factors affect patterns of initial biological coloni- 
zation and subsequent decomposition rate. 

Effects of topography In ecology are well known, and 
their effects also are important in studies on tli^comnosition 
rates. In areas of varied topography, e.g., some tundra 



situations, it is very difficult to provide meaningful generali- 
zations on rates of decomposition of organic matter. In 
such situations marked temperature differences can be 
recorded in the Utter layer on the north- and south-facing 
slopes of small hummocks, and (at least in summer) cellu- 
lose degradation is mofe rapid on die wanner south-facing 
slopes. Thus, microtopography may have marked effects 
on decomposition rates. 

Against this background of mbstrate and environmental 
heterogeneity is the heterogeneity in distribution and activity 
of the decomposer organisms (cf. Burges, 1960). Soii biolo- 
gists have developed the view of soil, with its litter layer, as 
comprising a mosaic of microhabitats for hjnlopical activity. 
These microhabitats support varying numbers and species of 
organisms. From the microbiological viewpobit the small 
fragments of organic matter (varying in tlieir chemical and 
physical state) may demonstrate very diffcrcni decomposi- 
tion rates. 

Another factor which can affect the quality of dead or- 
ganic matter, and therefore the decomposition pattern and 
rate, is the time after death dial the oiganle matter Mis to 

the litter siitface. This raises another problem in the study 
of organic matter degradation— the so-called "standing 
dead.** In many plant species there Is prolonged attachment 
of dead [larts to the parent plant and it may he years be- 
fore, under the influence of physical factors (wind, pre- 
cipitation, herbivore activity, etc.), these parts faO to the 
litter surface of the ground. These standing dead tissues are 
coloni/ed by decomposer oigeniims, this colonization being 
from spores on the surfke or from celts already active on 
or in the living tissvies prior to death (e.g., the potential 
role of weak faculutive parasites in the initial phase of leaf 
decomposition and the possibility of phyllosphere micro- 
organisms being active in the Inidal phase of decomposition). 
However, standing dead tissues are frequently exposed to 
more extreme climatic fluctuations than occur in ttie litter 
layer and materials are leached from them-this leaching 
has been shown to be an important nutrient input in some 
studies. The standing dead is also prone to drying out, and 
in some situations the standing dead appears to comprise 
dry sclerophyllous tissue of high tannin content. 

Many of the foregomg comments refer specifically to 
decomposition of organic matter at or above the soil sur- 
face However, mot production and death are major factors 
in adding decomposable orgamc materials to the soii. Dur- 
ing root growfli. the doughing off of dead oeUa and the 
production of root exudates all well known factors increas- 
ing the amount of soil organic matter, but these input fac- 
tors are difRcult to quantify and studies on their rates of 

decomposition have "ieldnrn been attempted. The rhizo- 
qphere and attendant root region phenomena (e.g., root 
surftee microfloras, myeorrMzas, etc.) have been inten- 

sively studied, hut the relation ot' these phenomena to 
decomposition rates of the materials menuoned above are 



Copyrighted material 



58 



MNMtPANKIMON 



not known. However^ the pnewnce of active and nuraeroui 
rhizospheie miciofloras are, for moat planti, generally 
accepted. 

Following deatfi of roota there la little faifonnation on 

their rates of decomposition— "litter bag" studies, in which 
dry weight loss of dead roots buried in the rooting zone is 
l>eing followed, are attempting to provide data on thlsque^ 
tion. Studies liave been made on the qualitative nature of 
microorganisms colonizing moribund and dead roots of 
various higher plants. If the root region is the zone of high 
microbial activity and production that many microbiologists 
have suggested it to be, then the absence of detailed studies 
on this zone may be a defect in IBP decomposer cycle 
atuidiei. 

In ferreslrial situations there is considerable consump- 
tion of plant materials by vertebrate herbivores, and a good 
portion of thii consumption is returned to the Htter iurftee 
as dung. This partially decomposed material deposited fre- 
quently in local patches, because of its peculiar physico- 
chemiesl characteristies supports a spedfie decomposer 

flora and f^juna of high biomass. This material may mark- 
edly affect the rate and pattern of decomposition of or- 
ganic matter in the soil in its vicinity (because of the dif- 
fusion of nutrients into the soil fr<mi the dunp). There 
appear to be few studies wixere the factor of herbivore 
dung decomposition is being studied. In many areas imle^ 
tebrate cot~sumers far exceed iho munirrials in consump- 
tion of the products of primary production or in the 
consmnption of litter. (In the litter the tale of fauna bi 
fragmenting organic matter has been mentioned.) Again 
much of this consumed material is returned to the litter as 
feces. Again much more work is needed on the mfcrobial 
attack of such substrates. 

The degradation of nitrogen-rich excreted materials 
has been studied in agricultural systems, but has re^ 
ceived little attention in IBP/PT projects. 

The examplea just given are further cases of the hetero- 
geneity of matartals entering the decomposer cycle and 
providing substrates for microbial explsitations. Any de- 
tailed field observations in any biome would provide a 
much longer list of substrates worthy of study bi relation 
to their rates of decomposition (e.g., no specific mention 
has been made in this contribution of wood decomposition). 

NEEDED EXPERIMENTS 

A good deal ol discussion has centered on the relative con- 
tributions of the dtfftrent eomponents of the soil biota 
to organic matter decomposition and to energy flow. Pliil- 
iipson (1966) quoted the general consideration that micro- 
organtens account for as mudi as 90 percent of the energy 

flow through an ecosystem. Earlier in tfiis coi>trihutinn 
reference has been made to tlie view that the majority of 
oiimie matter decompottloo is effected by the microflofa. 



The work of Edwards and Heath (1963), in which the 

decomposition rates in soil of oak leaf discs held in litter 
bags of different mesh size (ranging from QJOOi mm to 7.0 
mm), is of interest in this regard. TMa teduiique was one 
of progressive exclusion of components ul the decomposer 
biota with decreasing me^ size (i.e., in 7.0 nun mesh ba|S 
aU microorganisms and invertebrates had free access to the 
leaf discs; in the 0.003 mm mesh bags only the mleroorgn- 
nisms had free access). Tlie data obtained for discs in the 
bags of 0.003 mm mesh indicated no visible decomposition 
of the leaf discs over a 9-month period. Thus, it is accepted 
that the role of the soil fauna is of considerably greater 
importance than the bare energy flow figuies suggest. Ihis 
importance may result from their role in litter fragmenta- 
tion, inixifip and perhLips causing chemical changes-all 
these phenomena enhancing the ability of the micro- 
organbms to actively decompose the litter. The matter of 
chemical dianfu- and even enzymic degradation of compo- 
nents of litter by soil fauna are matters requiring more 
Study (e.g., Loxton, 1972). 

The addition of inhibitory suhstanccs has been used, in 
field experiments, to assess the role of soil arthropods in 
litter decomposition (Witkamp and Crosdey, 1966). Sbni- 
lar techniques have hecn siij^pcsfed. even attempted, to 
allow distinction between fungal, bacterial and fauna activi- 
ties bi soil and litter. This approach has strong inMal attno- 

tions, however, Parkinson et al. (1971) have summarized 
the dangers attendant on selective inhibitor experiments 
with raspect to soO biologfeal activity, ije., it is extremely 
difficult to ensure that the inhibitor used is brought into 
contact with all the microhabitats supporting the sensitive 
organisms; it may be that the fadiibitor used may itself act 
as a substrate for certain groups of soil organisms; the dead 
remains of inhibitor-sensitWe orgsnisms will themselves be- 
come substrates for decompodtlon; lod fte nmov«| of one 
group of soil organisms may release oHier gnwp* of orga- 
nisms for competitive influences. 

Another poasiUe approMli is that of using laboratory 
models where sterilized Uttn^ or soil is reinoculated with 
a known group or groups of soil orgsnims and the decom- 
position rate of added substrates is followed (by weight 
loss or respiration measurements). One of the major tedi- 
nical problems in this type of work is the appropriate 
sterilization technique- Parkinson ei al. (1971) have dis- 
cussed this. The realistic interpretation of data obtained 
from such experiments wi!! he difficult, however the use 
of such simple model systems may provide valuable data 
on various problems r^rding the aethrlty of individual 
groups of decomposer organisms. 

As has been stated earlier soil and litter support large 
and diverM microbial populations, therefore the micrahes 
themselves provide considerahlc amounts of organic matter 
available for decomposition. As yet no good data are avail- 
lUe on rates of mkiobial productivity or on death rates. 



Copyrighted material 



TERRESTRIAL 



89 



and althoa^ direct observations have demonstrated lyds 

of hyphac in soil (here is no data on rates of hyphal or 
bacterial cell decompotition. Here is another area needing 
experimental examinatioa. 

SUNMARV 

The foregoing comments Indicate that, for proper studies 
on decomposition processes, much data on other compo- 
nents of the ecosystem are required -these data are prin- 
cipally those on primary production and from meteoro- 
logicid studies. Eventually synthesis of data on decomposition 
and soil processes wHl be attempted at the site, biome and 
interbiome levels. Heal(1971 . 1972) has discussed the possi- 
bilities for synthesis of data on decomposition in the tundra 
biome. and various modelling ventures are now in progress 
(odieis are far better qualified than the author to comment 
on these aspects). 

Despite the apparent multiplicity ot problems in ter- 
reitfial decompodtlon the IBP/PT studies, wlikh have al> 
ready cmphasi/cd the vita! rolo of the decomposer cycle, 
will also provide valuable (important) data of a base line 
type in this ma)or subsystem of the ecosystem. These data 

arc vital tc applied studies on human impact on ecosystemS, 
and will allow the more precise definition of questions in 
fiituie ptocnuni. 

REFERENCES 

Alexaitdcr. M. 1965. Biodcg.McljtiiMi problems of nii.leciihir ti-ial- 
citmncc and microbial faUability. Advance, in Appl. Microbiol. 
7:35-10. 



Bwiei, A. IttO. Time and siM as hetoa in eeotanr. J. ieoL 
48:273-M5. 

Bdwald^ C. A., and G. W. Healh. 1963. Tfee role oTmO animals la 

bnakdown of le^riitiot. p. 76-84. In J. Doekien and J. vandar 
Drift (ed.) Soil Organisms. North Holland Publishing Co., 
Amttetdam. 

Edwardi, C. A.. D. E. Reichlc. and O. A. Ctoittey. 1970. The tale 
of toD invertebrates ia turnover of organic nniter and nutikat*. 
1^ 147-1 72. IH 0. E. Reidite (ad^ Aaalyila of Tnveate F«i«t 
Beoiyilenit. SpiingccVerlag, Naw York. 304 p. 

Harlcy, J. L 1971. Fungi in ccosyjicms. J. EcoJ. 59:653-668. 
Heal. O. W, 1971. Decomposition, p. 262-278./n O. W. Heal (ed.) 

I'undra Bivnu- W.nkin.i: NlL-L-ting on AnalydS Of EeOHniSaM. 

Kevo, 1- inland. September. 1970. 297 p. 
Heal, O. W. 1972. Decomposilion studies m tundra, p. 93-97. In 

F. E. Widfolaiki and T. RoiswiU (eds.) 'HiMln Biome Ptoowd- 

Ints IV. Italernaliaaal lieatlni o« Uokclcal PMdnclMljr of 

TWidra. Lanii«nd. USSR. Oetnbsv 1971. 320 p. 
Luxlon, M. 1972. SOidlei on Ae tMbatU miles of a Danliii wood 

toil. I. Nutritional biology. Pedobiologia 13 4'i4-tfi3. 
kiacfadyen. A. 1971. The »oil and its total meijtiL>li!.rn. p. 1-13, In 

J. Phillipson (cd.) Methods ol study m quaniitaltvc soil ecology. 

IBP Handbook No. 18. BlackweU ScientiTic PuMicatiom. Oxford 

and luiinbui](h. 297 p. 
MayaMdoa, J. 1971. U«e of ladloRspirameify in soil mlooUotaiy 

and (rfochomiMiy, p. 202-2S6. tn A. D. McLaren and J. Skajhu 

(ed.) Soil Biochemistry, Vol. 2. Marcel Dckktr. Inc., New York. 
ParkiMon. D . T. R. G. Gray, and S. T. WUIiims 1971. Methods for 

studying the ecolojty of soil microorganisms. IBP Handbook No. 

19. Dakkwcll ScicntiOc PubUcations, Oxford and Edinbiugh. 

116 p. 

RmiI, £. A. 1 970. Plant eompancals and lott oiiBnic matin. RaoMl 

Adfancw in PliylaclMm. 3;S9-I04. 
IMDIpKm. J. 19M. EMkikial aimietlca. St Mtfte'^P^ 

York. 57 p. 

Witkamp, M., and 0 A ("rossley. 1966. The role of jrthroptxis and 
■nicronora in the breakdown of white oak litter. Pedobiologia 
<:293-303. 



Copyrighted material 



MEASUREMENT OF 
PRIMARY PRODUCTIVITY 
BY GAS EXCHANGE 
STUDIES IN THE IBP 



RICHARD B. WALKER 



INTRODUCTtON 

In ils broad sense, gas exchange includes the uptake and 
evolution of CO2 in photusynthcsis and tespiratioa, ecMi' 
comitant evolution and uptake of in these processes, 
and the loss of water vapor in transpiration. However, the 
emphasis in this review on primary productivity focuses 
attention principally on the CO. exchange, with discusdofl 
being limited to terrestrial plants. 

By definition, COx vpMte by peen cells is line batis of 
plant productivity, always modified by evolution of CO, in 
n'spiratum. There has been interest in CO] tluxes tor over 
I centuiy. In the I920*s and 1930's the devetopment of 
equipment for more or less continuous measurement made 
possible closer examination of the relationship between CO2 
uptake and the external and plant factors affecting it. The 

:nt':iiiuctinn of infrared CO; analyzers about l*'50 gave 
further impetus to COj exchange studies in general and the 
faetoffl affecting rata* in partieiilar. 

Because of this substantial interest in COj oxchanpe. a 
considerable body of information existed before the advent 
of IBP renaich hi the mid-1960^a. Moat of the studies were 
autecological involving a variety o*" agricultural, forest, and 
herbaceous species. Generally, the technique of enclosing 
foliage In an assinUUtion chamber or cuvette was used, 
with the change in CO3 content of the gas stream being 
measured. 

NEED FOR FURTHER GAS EXCHANGE STUDIES 
UNDER THE IBP 

The emphasis from the start hi the IBP studies was upon 
vegetation and ecosystems. It was immediately evident that 
the existing autecological information was inadequate for 

60 



proper evaluation of gai exchange of these mora complicated 

systems. 

Marked improvements in technical aspects became avail- 
able or in wide use by the middle or late 1960'$: viz air- 
conditioned cuvettes, aerodynamic COj -gradient methods, 
improved measurements of environmental variables and of 
foliar temperatuiet. The need tor better aisessment of tliOM 

conditions jnd responses of the plant material affecting 
COj exchange has become more fully appreciated. Thus, 
adequate stirring of air to minimize boimdaiy -layer effects, 
monitoring of stomatal ape'ture, and surveillance of water 
status by psychrometry or Scholander techniques have be- 
come standard praetieet. The IBP hai not only benefitted 
from such technical advancements, but has actively pro- 
moted their development and acquisition in many cases. In 
particular, tfia IBP hn brought home the necessity of im- 
proved absolute accuracy in measurements, so that values 
obtained at one site may be effectively compared vnth ftno&t 
obtained at other sites usuaHy with difTeient equipment 
and methods, The nvjny aiivan;;e:neiirs of the recent years 
in equipment and techniques are covered in the authoritative 
treatise edited by Sestilc, HwtOcf and Jarvis (197 1 ). 

Recognizing the need for extension of previous auteco- 
logical Studies to the vegetation and ecosystem level, and 
the necessity of faicorporating the improvements in tech- 
nology . many countries included gas exchange studies in 
(heir IBP plans and efforts. (See Dinger and lianis, 1973, 
for a leview of U.S. activities.) 

EXTENT OF THE IBP GAS EXCHANGE ITUDIES 

Seventeen countries arc sponsoring gat exdnnge Itudiesal 
over 60 sites (Table I ). These sites are concentrated in 
Europe and North America, with locations in addition in 



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i 



c 

o 



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c 



i 



c 
3 



c » u 

2 E S 



— o 
S \ - 



" « e 
as « e 
H u 3 



ill 

* « - 

III 



62 



Copyrighteu liiaiori 



MiAMjneHRiT or raiiiAR v Mioouctivi-nr tv oas ixcmawoe stuine» in the iip 



63 



Australia, tsnd, Japan, and astatic A wide 

variety of vegetation is likewise included that may be said 
to represent in a broad sense tlie agricultural, desert, forest, 
grusland, and tundra (both alpine and arctie) biomes. 
Further, some 200 scientists are engaged in tlie work at 
these sites over the world. 

Already a substantial amount of work has been finished, 
but much more is still under way, since the assembly or 
acquisition of equipment, the development of field sites, 
and collection of data over seasons or even years consume 
much time. Further, the analysis of extensive data may rt- 
qiiirf loiii: iiJditional periods. Fortuinitelv . huwevet. the 
existence of internal IBP reports and sumiiiuries maices pre- 
liminary data widdy available, and the various IBP symposia 
and synthesis meetings have made oral presontalion and dl^ 
cussiun of studies possible even m their earlier stages. 

Certainly gai exchanfe studies have greatly increased in 
number, and usually In intensity and cxtenf as well, under 
the stimulus and support of the l bp. Fundmg has been sub- 
stantia]; in fact many of the programs couM newer have 
been planned or brought to fruition without this financial 
support. International planning has made for sharper goals, 
and widcspraad oompariaoni of methodology. These have 
enhanced the value of oompariions of icsultant dau. 

JUSTIFICATIONS FOR THESE EXTENSIVE GAS 
EXCtMNGESTUDIB 

Logically one can ask what values can be attahted from g^s 

exchange studies which justify the large investment in 
money and sckntiflc effort outlined above, in short, these 
can be stated as: 

1. Only through careful studies of net photosynthesis 
and both dark and light respiration can gross productivity 
lie deteraiined. Differences between species and varieties 

in gross as well as net productivity is of substantial practical 
interest in agriculture and forestry. 

2. Information on the tafluence of external factors Oight 
intensity, air temperature, vapor pressure deficit) and plant 
tactors (especially leaf temperature and stomatal and other 
kaf resistances) on net photosynthesis and respiration is 
vital to the development o( models of terrestrial plant 
productivity. If these arc to have good predictive values. 



they must take into account the Influence of wide fluctua- 
tions in these factors between different days, between the 
seasons of the year, and between one year and another. 
Models are just now bemg intensively worked on and aie 
often as yet based on inadequate data on these enviiornnental 
and plant factors. 

3. A major strength of the IBP lies in the integrated 
Studies of all components of eco^stems. Here gas exchange 
studies made of terrestrial plants-especially root respire* 
tion-are of particular use to those studying metaboUsm of 
the soil, bifluences of parasites, consumer organlamt. etc. 

CONCLUSIONS 

Extensive studies using eas cxchansc tocliniqucs have been 
conducted in many countries undei the auspices of the lUP. 
Some of these studies are completed, but most are eithet 

still under way or the data arc still being analy/fd However, 
preliminary reports and summaries certainly indicate that 
major progress has been made, especially in aiaesiing the in- 
fluenccs of both environmental and plant faL tnrs on assilllila* 
lion and respiration, so that good models of terrestrial 
plant productivity may be envisioned. The completion of 
all of the ongoing studies, and their analysis and puhliiation 
will greatly enhance theoretical and applied knowledge in 
this field, 10 that predictkm and modeling will be on a finn 
basis. 

AKNOWLEDGEMENTS 

Pieparaiion of ihi^ p^pet wa\ ixtppotxcd m p;irl by the Univertily of 
Wadiinglon and in part by the National Science l'oundalioll,Gnat 
No. GB-20963, ind it Contiibutioii No. 160 of the ConifenMH 
Ponsi BioRw. U.S. Amlyiit of Eooqntmu, I«Mn«timut MotaglGai 
Rragntn. Warm appreciation is exprened to all IhoK who ftarnilhed 
infonnalion about IBH programs in the various oountriet. 

REFERENCES 

Dinger. B. E., and W. F. Harris. 1973. Terrestrial primary produetioO. 
Proceedings of Interliiaroo Workshop on Caaeous Exchaqgt 
Methodology, Oik Ri^e Ntdami Laboiataiy, April 1»>I4. 
1972. 184 p. 

iwtA. Z.. J. Catsky , and P. G. lanis 1971. RuU ptetMm* 

thetk' p: <^'i-' -i'-n. manual of ■MlhodS.lheHaBBe. Or. W.Jwdt 

N. V. i'ubiulicrs.Hlgp. 



Copyr^hted material 



THE ROLE OF HERBIVORE 
CONSUMERS IN VARIOUS 
ECOSYSTEMS 



K. PETRUSEWICZ and W. L. GRODZII^SKI 



INTRODUCTION 

Before proceediiig to the main theme of this paper, It 

should be pointed out that: (1 ) this paper is a review based 
on already published data assumed to be correct; we do not 
take Into comiderttioii the smpllng prooedores and tech- 

niques u<^cd *,it :alculation of the data collected , (2 ) the 
data presented here cannot be regarded as in anyway ex- 
haustive; and (3) the role and rignlflcance of herbivores are 

considered in the context of the ecosystem. 

The theoretical importance of herbivorous animals in any 
eooiyst«n depends on a dfanfaiution of plant blomasi by 
grazing, and production ofhiglily organized matter the bio- 
mass of the herbivore (Figure I ). Generally, the nontrophic 
effects, i.e., pollination, seed dispersal, soil aeration, etc., of 
herbivores are not taken into account. Although these 
processes are neceamy for some plants, their role in the 
total ecosystem Is of aaeoiidary significance. 

HerblvDie activity can affect many ecologM processes, 
such as an increase or decrease in the primary productivity, 
a decrease hi the level of plant biomass, an increase in food 
for predators, including man (Figuie 1). An increase in 
diversity and complexity of ecosystem organization can be 
the result of herbivore pressure. Thus, by increasing the 
enei|y(blfonnation) transfer within the system, increased 
ecosyste!Ti stability results. The intensification of produc- 
tivity IS usually at the expense of plant sianJing crop 
(MooMss): a part of piimaiy production covers the cost of 

ecosystem ■ilabihValion. 

In discussing these functions of the phytophagous am- 
mabCPlgnse 1) the following aspects diould be considered: 



1 The greatest influenci's hv far exerted by phytophagcs 
in an ecosystem are connected with the consumption of 
plants, 

2. The ecological roles of phytophages are generally not 
alternatives. They are not of the "either-or" type, but they 
are of "fhis^nd-this" or the "this^nd/orwthtt** type of 

relationship. 

3. When considering plant biomass diminution, consump- 
tirm (O-the amount of organic matter consumed in a unit 

it time from a unit of space -is not the best measure; often 
the better measure is the organic matter removed from the 
standfaig crop (biomass) of the plants (Figure 2) (Petruaewiet 
and Macfadyen, li'TO). Unfortunately, there are very few- 
data on this aspect of ecology. Therefore, consumption (C) 
must be taken as our bnis father than (he matter itoMned 
(MR). 

HERBIVORE CONSUMPTION: HERBIVORE IMPACT ON 
PRIMARY PRODUCTION 

Obvhnialy, if a herbivore is to play a signincant role, it must 
remove enough plant material from the plant to effect the 
plant community and add sufficient biomass to its own 
body weight to initiate the grazing food chain, and hence to 
ineteaae tfie diversity and complexity of the system as a 
whole. 

It is difficult tu predict what percentage ot biomass re- 
moval would exert an important influence on the fimctioatag 
of the ecosystem. Under wme conditions even heavy graz- 
ing may be of minor importance (e.g., the Colorado beetle 
oomuming 20 peicent of potato ptaat leaves dccfleHef the 



64 



THE ROLE OF HERBIVORE CONSUMERS IN VARIOUS ECOSYSTEMS 



68 



ommuvcH ^» Occtmm or ptwit B 
O^nAMT I ncrMM of plant P 

■<OMA8S nT* D«cr«Ma of plwit P 

/ IncrMM of nr*iar«l 
c]M:kig rate 

CONSUMPTION 



PnOOUCTXJN 
OF 



, IncrMM Of •oocy*t*(n 
<*v»r»tty 



of OGOvyvtom 
ftetHvUon of higfily 

orgarMd m«tt«r 
DscompoMon 




OWTURBANCf 

oFEcoevsTeM 

INCAEAStNO 
OF PROOUCTIVE 

pfwcmacs 

INCREASING 
OF STABILITY 



FIGURE 1 Tha natur* of harbivorout knfluancaa on aeocystamt. 

yield by only I (o 2 percent). In other situations, very 
limited grazing may have a very great influence; e.g., Varley's 
(1967) investigation documentation of the wood increment 
losses of oak trees many times greater than consumption by 
caterpillars. 

It IS also difficult to Imagine an ecosystem without pri- 
mary producers, and similarly without decomposers. With- 
out producers there would be no energy stored for life. 
Without decomposers, the surface would be covered with a 
layer of dead organic matter in a sliort time and most im- 
portant nutrient elements would be removed from biological 
circulation. In contrast, at least theoretically, a biosphere 
functioning without consumers can be imagined. It would 
be a very poor biosphere and probably life within it would 




PLANT BIOMASS 



FIGURE 2 Matarial ramovad *ar*ui eontumption— a compariton 
of tropliic axehangi and tarm uaad to avaluata harbivora impact 
on plants. 



be very uninteresting. Nevertheless, such an ecosystem can 
be imagined. Many ecologists consider that herbivore con- 
sumption in ecosystems is negligible. For example, a fre- 
quently used method of estimating primary production is to 
measure the maximum standing crop and to ignore the 
grazed plant biomass. 

Consequently, a first effort was made to compile some 
available data on herbivore consumption. Data collected on 
small rodent consumption in different ecos)'stems are 
presented in Table 1 . In comparing the consumption figures 
in these ecosystems it is obvious that: ( 1 ) u single phytophage 
group, the rodents, can consume more than 10 percent of 
the available food, and <2) in spite of the variations, the 
simpler and poorer the ecosystem, the higlier the proportion 
that is removed. It should be stressed that the ecosystems 
summarized here are not ones commonly exposed to the 
action of outbreak species. 

The concept of "food available" has been mentioned. 
The food available to some herbivores has been defined as 
that "food which is easy to find, is being chosen and being 
eaten by these animals" (Grodzi/iski, 1968). The food 
available to consumers was described in the well-known 
studies on productivity of a beech forest in southern Poland, 
initiated by Dr. A. Medwecka-Kornas (Medwecka-Kornas' 
and Lomnicki, 1967). We present, after Droz'di (1967), a 
relationship between total aboveground primary production 
of the beech forest and the food available to rodents (Table 
2). In this forest, the food available amounts to 4.5 percent 
of total primary production. It is clear that this proportion 
varies, but generally it may be said that in the herbaceous 
ecosystems the proportion of food available is much higher 
than in forest ecosystems. In meadows and fields, almost 
the entire aboveground production can be considered as 
potential food for rodents and other herbivores. 

To illustrate the overall influence of herbivorous animals, 
we analyzed several of the better-known ecosystems in which 
the action of a larger number of phytophagous animals has 
been studied (Table J). Unfortunately, we were not able to 
find any one ecosystem in which the consumption by all 
phytophages had been studied. Therefore, we indicate to 
which groups of phytophages upon which the data are 
based. 

The following points emerge: 

1. Tlie value of phytophage consumption is consider- 
able; it amounts to 8 to 20 percent (2 to 5 X 10* kcal/ha-yr) 
in terrestrial ecosystems. 

2. The comparison decidely supports the well-known divi- 
sion of Odum Into "detrital" (oak-hornbeam forest) and 
"grazed" (meadow and cultivated field) ecosystems. 

3. Even in the terrestrial ecosystems, considered as be- 
longing to the typical grazing food chain ecosystems, only a 
minor part uf the plant biomass ( 1 3 to 20 percent) passes 



K. mnunMncz m. u onooziNHn 



TABLE 1 RodMM 



In Vwioin Ec w y t min 



Eooiyttein Type 



10^ koi/ha-yi 



Food Availabte (F,) 



CMiamptloaCC) 



Temperate fimit 
(4 pine) 
(2< 



fomt pbfltttion 



(4 



NortlMni Uift (AUuke) 

MiaotiisiBfonnlMid N«8Q/ln 

N"lj(KW»a 



1,024-16,190 
1.95&-2.050 

2.395-19.700 



U20 
40,700 



21-lOS 
40-129 

131-699 



179 



3«5 
4^ 



a<-i.9 

3.0-44 



13.S 

a9 

11.3 



Ryskowtki (1969) 
Gradriukicf 09«9> 
Gi«tcinia(1971) 
OndOttMettL (19M) 

MyUymilci (1969) 
Colley (I960) 
llinsson (1971) 
Cro(lcinslu(I971) 

TN^(l9i9} 



TABLE 2 Primarv Production end Food Availabl* tO 
Rodantf in a Be«ch Forett (After Oroidi, 1967) 



lO' kcal/ha-yr 





PUnt 


Food 






Production 


Available 






<v 


(F.) 


(») 


yiBilie 

IHIDl 


1.080 


920 


IS 


Ttaeieoda 


225 


202 


90 




(2B-4S6) 


(22-360) 




IVealeav*! 


1M2S 


670 


S 


(twiB>.bark) 


29.140 


110 


a4 


Fungi and 








inveitebiatet 




S3 




TOTAL 


49370 


I.9S9 


4J 



through this chain The grazing food chain is considerably 
more important in tlie grasslands than in the forest ecosys- 
tem (13 to 20 pereent vs. 7.7 peieeot). Neverthetess, In both 
forest and meadow ecosystems the detritus food chain is 
more important than the grazing food chain. Only in an 
oUgotropMc lake, fat pelagic (plankton) ecosystems, is the 
major part of the bioiniiss (^0 percent) grazed. Suchincoi^ 
system can be considered as an "eugrazing" type. 

A further illustration of the magnitude of herbivore im- 
pact on vegetation may be made by comparing available data 
on forest and grasrimd herbivore consumption (Figure 3). In 

this comparison, forest ck-aringb up to 4 years old are in- 
cluded in the grastUnd ecosystems, because the pioneering 
stage of seoondwy suGcessiiOii of fomt tostalar lo the grass- 



TABLE 3 Primaiy traduction Oansnmad bi Soma TanasttM and FraSbMMar EoosyiMms in P rt and 





Food 






C/F, X 100 






Available (F.) 


Knows Conntmen 


Consumption 


(%) 


References 


Oak hornlxim forest 


21.940 


Munmali. bitdt Tortrix, 


1,700 


7.7 


Medwecka-Kornsis. Lomnieki, 


(Niepolomice) 
(10^kcal/h«-yr) 




other Lepid. larvae 






and Bandola-Ciolczyk 










(1973) 


Uncultivated meadow 


20,750 


Orthoptera, Homopteia, 


2J27 


13.1 


Bfeymeyer(1971) 


(Dciekaaow) 




IMpieia, Lapkkipieia, 








(to* kcal/ltt-yr) 




ledMis 








Rye field (TUtcw) 


41.700 


itflCRMiit. Diptera. 


4^00 


ia9 


T^olan (1967) 


fin^ k.3l,''ha-yc> 




Colorado beetle 








Poialucs (Tutew) 


26.600 


Microius. Uipteia, 


4.870 


19.8 


Trojan tl967) 


(IC)' kcal/lu-yt) 




Colorado boaite 








Mew-aiigolrophic 


0.77 


Plankton 


0.69 


90 


Gliwicz and Hillbridit* 


(Pflakno Uk«) 










Ukowdta (la preta) 


(Bd/Mh) 
Ifeiotropliic 


0.07 




0.3R 


44 


GMwinaodlllllMkhl- 


(Taltowisko Lake) 










llko«iiBi(faipr«is) 


(cal/24 h) 












Eu trophic 


Ol3S 


Hiaklea 


0.22 


10 


Chwicz jnd HillhDJht- 


(Mlkol^i Uke) 










Ilkowska (in preu) 


<eal/a«li) 













Copyrighted materigj 



THE ROLE or HIRBtVORE OONIIIMERS IN ViMIOUilOOtVSTIM 



67 




Jl 



iiiiiiiiiM.... 



Forest 
••ocysttms 



FIGURES ExMnpiw of iMrfaivoMeomuinption in gratftand and 
foratt •coaystamt (10^ kcal/ha-yrl. 1. Microtus (Myllymaki, 1B69); 
2. Colorado baatiM (Trojan 1967 3 Plant hoppan (W»agart and 
Evans. 1967), 4. Gnmhopftmn iWiogun jind Evan*. 1967^' S. Or- 
Ihoplara (Wiagan and Evarti. 1967); 6. Cicadalla (AndrxaiavMka. 
1M7); 7. RodMMi 0 1— ion. 1971).- 8. Mytmiea (Pftal, 1M7); 

t&ntt 11. ttyrmiea ||Pif«al craA. 1t71); 12. Pogonomymmt 
WBaprtwidEwa. tW7): 13. Uierotut (Trojan, 19«t): 14. Ro- 
danti (Grodzinskr. 1971). 15 Rod»nM (Ryukovixl Tgfi9h 16 
Rcxiantt (Grodzinifci etal., 19691. 17. Rod«nts IRyukomki. 1969); 
18. Rodani* |Grodttn$ki et al.. 196Bh 19. Lapidoptara (Wintir, 
1971); 2a Ground aquirral (VVi«|irt and Evm. 1967); 21. Cur* 
wNonMn IFtink*. 1971);22.0r«iaptm IWiaiwK 
1M7); 29. IMnii WgiA wK M, 19891; : 
1«71): & » M n> i W W iprt inrf iwi 

<Rvttl(«>«Mhi. 1969); 27. Spittfabooi nm«gart and Evant. 1967); 
2S. CiwcidionidM (Funk*. 1971); 29. Pwoanytnia (Wiaeart and 



plots there was a 40 percent increase in the primary produc- 
tkm compared to oontrol ploto. Skioe the experiment ii4iicb 
involvetl using pesticides lasted only one growing season, it 
is difficult to predict the relationships after several years. 
Howawr. if the 40 percent increne In piimaiy produelioD 
is attributed solely (o consumption an abnormally high value 
is derived. The examples discussed provide iilustraiioitt of the 
comiilex intersctioiu between phytopluget end pfoducen fai 
anecoiystem. Tlieir direct impact on the primary produc- 
tion ii diown by a consumption rate of the order 4 to 40 
peicent of priinuy praductiom; mon complex ralitjondiipi 
are obKure. 



HERBIVORE CONSUMERS AND CYCLING OF 
MATERIALS 

In the beginning of this paper It wat bidleated that phyto- 
phages may also play a role in accelerating the cycling of 
material by, for instance, comminution (crumblii)g) of the 
plant biomav, thus nuUiig It easier for thn mineralization 

process to be completed by reducer organisms (bacteria and 
fungi). These processes are dependent, to a great extent, up- 
on the assimilation efficiency of phytophagous animals. 

The assimilation efficiency of herbivores has been vari- 
ously expressed. For comparison of some data from the 
literature, see Table 4. The range of values loi food energy 
rejected as feces and urine is very broad. Of the food energy 
consumed, rodents as?.!iniljte ahoiif "50 percent, the elephant 
40 percent, and some lepidopteian larvae only 20 percent 
Crable4). 

Obviously, there is little need to emphasize that the im- 
portance of phy tophages compared with decomposers will 
depend on their standing crap, i^e., mean numbeis and masa 

of individuals feeding during a tHven period of a year (num- 
ber of individual days i )) . Consideration must be given 



TABLE 4 Reject* (Feces and Urine) Returned into the 
Ojfoio of Matsrtal by Differ ant Herblvofe Conswnara 



land type. Savannas and semideserts have been also included 

in the gra'island eco';ystem category. TMsabove oomparison 
(Figure 3) leads to two conclusions: 

1 . The value of plant biomass constuned is sometimes con- 
siderable and attains the level of several mdlion kcai/ha-yr. 

2. Based on the absolute values of consumption, evidence 

is that in crassland-typc ecosystems consumption (grazing 
food chain) is more important, and that in the forest -type 
ecosystem the detritus food chain n more Important. 

Andrzejewska and Woicik (1971) showed that after the 
total clinibntloii of phytophagous inaects on 4 m' meadow 



FU/CX too 

Goaiiuner Spades (ft) Refeiencs* 


Field mouse 


11 


OmidsdMS) 


(Apodemut anrariux) 






Furopcan hare 


32 


ll»idtt(l9M) 


(Lepus furopaau) 






wad Imar 


24 


Gen(l9ST) 


(Sttf icro/ii) 






Orthoptera 


30 


OdodnjrUM*) 


(Chortipput donMa) 






Ixpidoptera 


31 


Nakaffluta (1965) 


(Plrrii bnaleKH 






tJcphant 


60 


Pctridr\ and Swank 


{LoxodoHia d^Mena) 






Ixpidoptera 


79 


Janda (1960) 



(Croeaa itplenlnonalu) 



Copyrighted material 



08 



K. KTRMCWICZ an* W. L. gnOOZI Awi 



not only the numbers of individiuls coniumtaig, but also 

Iheir size. So we come to the very important value, quantity 
of bioinas&-days (B I ), i.e., the amount of consumer bio- 
na» during a given period of a year, it may happen that 
rodents, which reject only about 1 1 percent of the food 
consumed, may be able to excrete a ^cater quantity of 
feces and urine (FU) than Ooesus larvae, which reject 80 
percent of the food consumed during a short time period 
only. The data for consumption and the comparison of 
assimilation efficiencies (Table 4) aie expressed in the moct 
comparable uniis. i.e., in terms of energy-caloiief re> 
jected over calories consumed. 

Here we AoM point out the problem sometimes ne> 
glected by ecologlsts: of the two components of rejecta (FU ). 
feces (F) contain the major diare of energy in comparison 
with urine (U). Thus, often urine (U) is ignored in the study 
of energy now. Quite different conciusiuns prevail if one 
considers nutrient cycling. Considerably more nitrogen is 
contained in urine than in the feces (Table 5). The nitrogen 
in urine truiy be assimilated directly by plants without the 

action ot d.'joiTipiisi'r'; 

To illustrate the contribution ol herbivore consumers in 
the decomposition of organic matter, data were compiled 
on the annual inflow of dead organic matter of plant origin 
in four types of ecosystems (1 able b and Figure 4). This 
coin|Mri$on was poadile udng the following assumptioas. 
In meadows and forest 20 percent of the total annual root 



TABLE 5 Nitrogen Efflux (Ex 
prasied « Percentage* of Consump- 
lion) by a Vale and fig. In a Steady 
State of Nitrogen Balance (without 
Retantion for Growth and Rapro- 
duetioiil 





Vole 




Comniaption 


100 


100 


Fecev 


36 


30 


Urine 


74 


70 



MOWNMIAOOW (NM2B> SiBADOMr 




BtECM WOOD RY£ -FIELD 



FIGURE 4 Oimifc mmmr mt y tM in She w oa yi liai ivfi X 
lioaMifrVfl* OaH!.* atgaiiie nailHr In lollj 0« tfaconpaMrxMlr, 
plant nutrianli— plant organic mattar latumad to io4l; lafi arrow, 
daad plant mattar; ri#it arrow, plant mattar comminvtad by 



production diet yearly. Fhre percent of the annual wood 

production returns to the ecosystem as dead organic plant 
mass, in the grazed meadows 30 percent of the plants con- 
sumed return to the ecoqrstem as rcjaeta (FU) from grazing 
animals in the form of crumbled organic matter (if the cattle 
are on the pasture for 24 hours per day). We were not able 
to find any suitable single collection of empirical data for 
the satne ci. nwstcnr. calculations were based on empirical 
data tal<cn t rom various sources. In analyzing these com- 
parisons (Figure 4) the following features become evident: 

1 . The beech-wood forest and grazed-meadow ecosys- 
tems are typical examples of lutural balanced detrital and 

grazed food chain ecosystems, respectivciv In the detrital 
food chain ecosystem only a minimal amount (.less tlian 
10* kcal/ha-yr) returns to the soil in the comminuted form. 

Most of tlie decomposition processes are due to tl\e action 
of detritophagous organisms. But evto in a "classical** 



TABLE 6 Primary Production and Organic Matter Returned to Ecosystem (10^ kcal/ha-yr); Assumptions Used are 
Indla a tad by faiwiiha s a s 



EcoqrsleB Type 


Production 




Annual Return to Soil 






FoUags Wood 


Itooti 


Conditions 


Sabtotal 


Totd 


Mowed neadow 


25.8 


23.7 


Ity? unmo\*cd (2Wc of limis) 


7.3 










90%ast UandbodMsfrom lOVbgraied 


13 


9j6 


Crud meadow 


2SJ 


33.7 


lOK unmowed (2Mof raott) 


7.3 










30Kai hX< from 80%|iasod 


6.4 


13.7 


Beechwood forest 


13.< 43.0 


&6 


95% of green parii (5% of Wood) (70% of toots) 


16.g 










5% of grazed Icjvc^ 


04 


174 


Rye field 


43.» 


I8.S 


10% unmowed gtccn parts, all roots 


22.9 










90% at FU and bodies ttam 10% gtaasd 


3.9 


2gJ 



Copyri ahtg d rnateual^ 



THE ROLE OF HERBIVORE CONSUMERS IN VARIOUS ECOSYSTEMS 



69 



grazed ecosystem, as in a grazed meadow, more than SO 
peieent of plant bkNiiM imims lluoui^ Hm detritophags 

food chain (7.3 X 10' vj. 6.4 X 10' kcal/ha-yr). 

2. The ecosystems chosen differ distinctly in the amouot 
of orgaide matter retumbig to the eeoiyttem. 

.i. The mown meadow and rye-field ectjsystems, i.e., 
man-made or man-changed ecosystems, are different when 
compared with natural or lemlnitonl ones. 

4. Sijtnificanlly smaller amounts of organic matter con- 
tribute to mineral cyding in the mown-ineadow ecosystem, 
fha bdanoa of plmt nrineial nutrients here being negathw. 
The nutrients necessary for life of the ecosystem must be 
imported via the hydrologjcal route (flooding of meadows, 
etc.) or by the help of man in the form of fertflfzers. 

5. The flux of organic matter in the two naturally bd> 
anced ecosystems (fwests and pasturea graiad by big harbi- 
vorous animals) has a mean value of 1.4 to l^SX ICr kcal/ 
ha-yr. 

6. Much higher Huxes of organic matter occur in Held 
crops, because about l.S to 2 times more organic matter 
ntuins to the cultivated flelds(the ftequent addition of 
dung not being taken into account) as compared with the 
pasture and forest ecosystems. Even the amount of the annual 
flux of noncfumbled (not comminuted) organic matter 

In the ecosystem is higher than the total organic matter flux 
in the forest and pasture ecosystems. This is the result ot the 
armnal killtng and ploughing under of the whole root sys- 
tem which, in other ecosystems, occurs as a continuing 
dying-off process. It is worth drawing attention to the very 
Ugb levd of microorganim aetiviqr which must be Iiif 
volved. 

Ctdthnted fleMs and mown meadows occupy, at laast 

in Central Europe, more than 50 percent of the total area, 
in these strongly altered ecosystems intensive ecological 
pToceaes are takfaig place, and it seems to m that the work 
of the ecdloeists, at least concerning the cultivated fields, 
should be concentrated (besides on pest control) on the 
aeaidi for ways of inttmifying tiie decompodtioA pioceaaes. 

CONCLUSION 

It can be clearly demonstrated that, even in normal ecosys- 
tenu without mass outbrealis of pests, the impact of herbi- 
vores can be significant. Herbivores have been stated to be 
responsible for very different ecological processes, such as 
increase or decrease of productivity, stability, etc. An at- 
tempt wHI now be made to show the relation between Ihe 
ecological and/or physfado^cal properties of herbivorei and 
some ecological processes (Figure 5 ) 

The most important consumer population property is 
abundance, i^, mean yearly biomass and tiimovec. To be 
significant as a consumer, the herbivore population must 
have a high mean biomass. To be efficient as producer, the 



HERBIVORE PHOPEHTY ECOLOGICAL RESULTS 




herbivore must have high mean biomass and/or high turn- 
over nte (Figure S). Excessive consumption (grazing) can 
cause a smaller or greater disturbance in the functioning of 
an ecosystem, or even destroy it. Moderate grazing often 
may increase primary pruJuctiun and pcoducMvity pracesses 
through more rapid mineral cycling. 

Efficiency of assimilation can increase secondary produc- 
tivity and, hence, increase the retention of total informs 
tion in the ecosystem; it can, but it need not. liven the very 
efficient assimilator with only a short life span (i.e., high 
turnover) can increase praduetWity but not the retention 
of highly organized biomass Incrficient assimilstora il^ 
crease the cycling of materials in the system. 

Enicient producers with low turnover contribute to the 
retention of highly organized organic rtiatter, and in this 
way increase the complexity of system organization. Effi- 
cient producer populations with a high turnover can offer 
to predators a considerable amount of fonj ;ind hence 
start a food chain but at a high price in terms of energy. 
Such aoonsumer win accelerate producthrity and increase 
the entropy. The entropy <;hould thenbehlf^ifsucha 
herbivore has a high metabolic rate. 

By inerearing bitmiais retention and/or inteniifleation 
of productivity processes within an ecosystem, herbivores 
contribute to the diversity and higher organization of the 
system. Unfortunately, In the ptesent Hate of ecok^cal 
knowledge, ail these proceaBBS cao only be daa cti bed In 
general, semiquantitative terms. 

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Andrzejcvksk.t, L !967. Estimation i>f the crreLH of feeding' of At 
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AndmlvNaka, L, and Z. Wojeik. 1971. Praduelivity inveti%ition 
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Broynwyw. A. 1971. FrodKiMtjr invoslitatiini of two typw of 

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Chlodny, J. 1969. The energetics i>t IjivjI divdopmcnt of two 
species of grasshoppers from genus Cftortippus I'leb. Ekol. 
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Dioxdi, A. 1967. Food piefcnace food diavstibUity aad Ihe ihp 
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Drozdz, A. 196b. Di{;cstibiliiy and assimilation of natural foodiin 
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Fiinke, W. 1971. Food and eneigy turnover of leaf eating iniwu 
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Grodzinski, W A n/ni^ ki K J;.:i jv. jiid P Mipula. 1966, Fffcct 
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IM. 

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298 p. 

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Tetrealtial Ecoiyaieou (Principles aad UtedMdi). VoL 11. PMM 
Academy of Sdenoes, Wamw. 879 p. 

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Energy Mow fhrough Small Mammal Populations. Polish 
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(Serman Soiling Project. Springer Veilag. Berlin-Heidelbeig-New 
York. 214 p. 



SECONDARY 
PRODUCTIVITY 
IN THE SEA 



D. J. CRISP 



INTRODUCTION 

The complexity of biological systems maket it neceisaiy 
to impose limitations on the way in which we look at 
them if progren towards general principles is to be 
achieved. The meaniemeiit of energy flow through eco 
QTStemt has been the dominant dwme m much of the 
Inlcmatioiial Biological Ftognnune. By making energy 
content the common denominator for the comparison 
of different ecosystems, it is hoped that the trophic rela- 
tionships of various habitats from a great variety of lati- 
tudes and regions can be better understood. Inevitably, 
thii ibetiaetkm leaves out of account the faunistic conv 
position, community structure, feeding behaviour and 
food preferences ul the organisms concerned. The juicy 
steak and the old leather boot become equala in the eyea 

of the calorimeter 

A major problem is the endless variety ot units of mea- 
sure employed in produethity literature (Table l),aiid llie 
failure of authors to specify Ihem. Even the great work of 
Zenlievitch (1963) does not state that the units of biomass 
ueed are wet weights-in themselves a crude measure with 
which to i nmpare the living matter of animals and plants 
from different groups and environments. 1 have therefore 
endeavouied to keep to the following units throu^Mut: 
biomass in kilocalories. area in square meters and time in 
jrears. Where precise comparative calibrations are not 
leadily avaibbie I hive uied the coBvenlon factors in TaMe 
2. They are likely to be quite as pnciie as nmidi of the raw 
data. 

71 



The idea of ignoring speciOL diversity and following the 
broad pattern of changes in nutrient elements and in the 
population dendties of primary producers and herbivores 
was applied successfully by marine biologists to open-sea 
eco^stems as far back as the middle and late twenties. The 
underlying principles established In the classical works of. 
for example, Atkins ( \^2(->), Cooper (1933), Harvey (1928) 
and Marshall and Orr (1927, 1930) have since been refmed 
and extended to account for seasonal, latitudinal and topo- 
graphical variations in productivity over the world's oceans. 
These early successes have to a degree preempted the part 
that fundamental studies of oceanic productivity nuglit have 
piqred in iBf . I doubt whether they sliould be aacribed to 
■ny superiority of marine over terrestrial ecologists; more 
likely, tliey can be explained by the circumstances of the 
enviranmeot Itself. 

CONDITIONS IN MARINE AND TERRESTRIAL 

ENVIRONMENTS 

The open sea is much more difficult to sample and explore 
than a typical terreatifa] environment It Is an fadioapitable 

place and it extends in three dimensions But even more 
important is the fact that it is continuously on the move. 
Largeecde tufbuJence tenders merkbig and bupectlon of a 
small body of water onSUCCeSnve iKcasions ver> difncult 
(but cf. Cushing and Tungste, 1963). In terrestrial and in 
many freshwater environments specified groups or popu- 
lations of organisms liv ing m siiull, manageable and well- 
deflned areas can usually be examined at regular intervals 



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74 

TABLE 2 Conranion Fieion 



Conversion 


Multiplier 


g wet fle^ wcit;ht to Iccal 


X 0.5 


g dry wi'ighl to kcal 


X 4 


$ (try organic (ash-free) weight to kcal 


X 5 


g carbon <kC) 10 kcal 


X 10 



by quadrat or transect methods. In contrast, the marine 
Uotogiat must accept samples takeit at lamlom from a very 
large stud\ rsrea, such as the English Clianncl or I^^ng Island 
Sound, and must in consequence saciifice finer detail for 
the sake of generalities applicable to the larger system. 
Fortunately, the water movements that make station 
marking to difficult offer compensations. They make the 
chemical and physical propertws of the water mass far 
more uniform in space and more conservative in lime than 
those of a comparable area of land surface. Consequently, 
relativdy infrequent observations at few stations can often 
be fitted together making a seasonal picture representative 
of the whole area. But this advantage does not seem to 
extend In the same degree to the orgynians themsdm. 
Plankton is nuturiuusly patchy in its distribution and its 
study requires specialized statistical treatments of the 
kind that have been developed as part of 1BP*PM (Cassie, 
1%2. 1963). 

An even more profound difference between oceanic and 
temMiial systaim arises from die fact that the trophic 
structure of the former extends in three dimensions. Apart 
from a scarcely significant aerial plankton and its avian 
consumers, the biologically important components of the 
air are disseminuies without trophic activity, for exampkt 
winged seeds, pollen, spores, flying vertebrates and insects. 
But aqueous habitats, because they provide buoyancy and 
a fuO range of nutrient elements, can support trophic ac- 
tivity throughout their depth. Hence, whereas all trophic 
levels in a terrestrial ecosystem coexist more or less in the 
same phuie, those to aquatic ecoqrstems beconM separated 
vertically by the sinking of dead organisms or their residues 
under the action of gravity. Primary production takes place 
at the weltiUiuninated fringes or at the surface of oceans 
and lakea, and sncce'^sive trophic levds attam greater piomi* 
nence with increasing depth. 

It is unfortunate tint planktonic, pelagic and benfltle 
zones have generally been studied separated hv mari.ic 
ecdogists, no doubt because each requires different equip- 
ment and expefttae. As a result, their trophic connections 

arc still very little understood. NcvcrthclLss. il sccr.is lIcji 
that an area of sea should be regarded as a single ecosystem, 
superficially rather uniform, but witfi a vertical stratifica- 
tion of trophic levels. Indeed, it would be as artificial to 
separate the benthos from the planicton as it would be to 
separate ground plants and litter In a woodland ecosystem. 



PRIMARY PRODUCTION IN OPEN WATER 
ENVIRONMENTS 

Before I can discuss secondary production, it is necessary 
to show how the fundamental differences between ter* 
restrial and aquatic ecosyslem? outlined above influence 
the character of the primary producers and thereby ail 
those that depend upon them. Plants in aquatic ecosystems 
exist for the most part as single cells of very small size 
widely dispersed in the surface waters. They can enjoy the 
advantages of tiiis form because Am niedlttm la bu<^ant 

and because the supply of nutrient salts is not limited tD a 
particular stratum. Wliat are the advantages of unicellular 
dispersion? 

In all biolc^t;ica! s\ ^tei'ns, whether anima!, plant or social, 
the larger the size of the organism the longer is the path of 
diffusion or communication and the less efRciently H can 
work. BureacracicN. fur example, are much less efficient 
than families; the larger they are the worse they function. 
In animals, small size is always associated with a high poten- 
tial rate of metabolism but in plants smallness has two fur- 
ther advantages. For a given quantity of plant tissue a large 
area to volume ratio not only allows more light to be inier> 
cepted but also provides a greater Surface atet across which 
nutrients can be mobilized. 

Phnts on land are less fortunate. Befaig confined to the 
plane of the earth's surface, they need roots to obtain water 
and nutrients and shoots to obtain light. In terms of com- 
petition, as distinct from absolute efficiency, there is a 
premium on size. Indeed, large terrestrial plants have come 
to resemble some human institutions in which sheer size 
gives them the advantage of being able to smother their 
rivals despite the accompanying loss of efficiency and the 
quantities of dead wood that become built into tiie sup- 
porting system. 

F^ie 1, taken from McFadyen's (1964) comparative 
account of early work on terrestrial and aquatic ecosystems, 
shows that the conversion rate of the same quantity of 
solar energy taito secondary production is about ten tbncs 
as great in aquatic as in terrestrial ecosystems. This is the 
well-established index of "ecological efficiency " which can 
be used to measure die transfer of energy from one trophic 
level to the next. However, a more spectacular contrast be- 
tween aquatic and terrestrial ecosystems is seen in the very 
low standbig stock of aquatic ecosystems (10^30 kcal per 

sq. meter) and the cntimiously greater quantity of living 
matter in terrestrial ecosystems (2,000-5.000 kcal m''). 
AHhou^ the biomMS of the aquatic lystems Is more than 

two orders of magnitude lower, their production and rela- 
tive transfer of energy to herbivores is higher. A more com- 
plete set of data for a number of ecosystems is given in 
Table 1, which includes productivity (P) per unit of biomais 
(B). Values of P/B are generally a function of size of pri- 
mary producen and it is dear from the table that the micio- 



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SECONDARY PRODUCTIVITY IN THE SEA 

ENERGY FLOW IN ECOSYSTEMS 



69 / 




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FIGURE 1 Energy flow palhs for primary production o< lix aco- 
tystsmi, from McFadyan (1964). The boxM r«prmt biomaai, tha 
tolar input it thown antaring «t 6 o'clock, ar>argy loa* in ptiotoayn- 
ttiaaii at 9 o'clock, plant ra^>irition at 10 o'clock, nal primary pro- 
duction avaJlabIa lo harbivorat at 12 noon, and mortaHty loaaai 
availabia to dacompoaars at 2 o'clock. Uniti mad ara itandard 
nutritional units par l)actara wfhich ihould ba multipliad by 100 
to eonvart to keal m~ 



scopic primary producers of all aquatic systems have very 
high efficiencies in terms of P/B. Since most of these or- 
ganisms are unicellular, with divisions taking place every 
few days, the values of P/B are of the order of 100 yr'' . 
Not only are rooted plants larger and therefore slower 
growing than microalgae but they also contain a much 
larger proportion of material which is metabolically Inactive 
but which is nevertheless included in the biomass. Such 
substances as cellulose, lignin and cork constitute a high 
proportion of the biomass of a forest ecosystem. 

RELATIONSHIPS BETWEEN PRIMARY AND 
SECONDARY PRODUCERS 

Differences in the physical structure of the terrestrial and 
aquatic environments have led to primary producers with 



75 

very different sizes, forms, growth rates and constitution. 
These differences have in turn given rise to an entirely dif- 
ferent relationship between the primary producers and the 
herbivores that depend upon them (Crisp, 1964). The very 
large standing stuck of plant life in all natural environments 
on land is immediately obvious so that even an untrained 
observer could hardly overlook the dominant role played 
by plants in terrestrial ecosystems. However, the significance 
might escape him. 

Evidently much of the terrestrial plant tissue escapes 
being eaten by herbivores and is dealt with instead by de- 
composers. Furthermore, with few exceptions, land-living 
herbivores are not wholely destructive of the plants on 
which they feed: they consume part, usually foliage, leaving 
the rest of the plant to regenerate. Sometimes the damage 
does not greatly affect potential plant production (e.g., 
Trojan. 1967) though sometimes it docs (e.g., Varley, 1967). 
The indigestible character of much terrestrial plant tissue 
may discourage herbivore attack. At all events herbivores 
do not effectively control the biomass of land vegetation. 
Consequently the balance between plant and herbivore can- 
not be a simple matter of the available food supply; some 
other limitation, such as control of herbivores by carnivores, 
must e.xist in plant dominated terrestrial ecosystems. 

An entirely different relationship applies to the open 
water ecosystem. The small size of the primary producers 
precludes any amicable arrangement whereby the herbi- 
vore browses on a permanent field of vegetation capable 
of continuously making good its losses. Microalgal cells can 
only be eaten whole. The phytoplankton survives only be- 
cause the remaining cells become too sparse to support 
continued herbivore grazing, yet retain a sufficient repro- 
ductive potential to recover after the herbivore population 
has diminished. 

The active herbivores of microalgae are the microcruj- 
tacea. mainly copepods in the sea and cladocerans in fresh 
water. From purely mechanical considerations the predators 
of microalgae must themselves be of small size (Parsons and 
Le Brasscur. 1970) and will, in consequence, have high 
metabolic rales and food requirements. 

The second group of marine herbivores are the sedentary 
niter feeders. Since they have evolved fine filtering me- 
chanisms to strain off the microalgae from the water, their 
size does not have to relate to that of their food particles 
and so they can attain dimensions considerably greater 
than those of the microcrustacea. Their food requirement 
per unit of biomass ought therefore to be lower. But on 
account of the demands of a pelagic larval strategy (Crisp, 
1975) and their often dense accumulations in places where 
there is a convergence of streams of water from a wide 
productive area, they are prolific consumers of primary 
as well as detrital energy, especially in coastal and 
estuarine regions. Thus, in the sea. both active and seden- 
tary herbivores are capable of consuming very quickly most 



76 



of the energy tlut the primeiy imodiicen nuke available, 
and so keep the standing stocic of phytoplanlcton at a (da- 
lively low level. 

In contrast to the chaiacteriftic temttrial situation In 

which herbivores are limited and vegetation permanent, in 
Uie mat ine environment herbivores control, and are con- 
trolled by, stocks of phy toplankton. Such a Atvf^ predalor- 
prey relationship at the base of the food chain is likely to 
produce severe fluctuations in biumass and production, and 
may account for the preponderance of opportunistic life 
styles in the sea (Crisp, 1975). 

MICROCRUSTACEAN HERBIVORES 

Copcpods arc the most important herbivon-s nf murine food 
chains and have duly received most attention. Cu&hing and 
Tungate (1963) attnnpted to measure the grazing rata 

Calami': in patch of water kept under constant surveillance. 
The production attributable to the four main diatom species 
present was estbnated from the change bi size of ffustndes 
during the period of the survey (rii<;hi'in,, t'?5.si, nnd also by 
integrating solar radiation through depth and time and apply- 
ing the lelationship between division rate and energy demon- 
straled by Lund f 1950). The difference between the observed 
algal biomass and that expected from the production data 
represented the total mortality from all causes, and tiie re> 
gression of mortally on beibivore weight was assumed to 
give the grazing mortality per unit herbivore biomass. When 
the algal grazing was partitioned between Cakmus and other 
herbivores, it appeared that initially the amount eaten was 
greatly in excess of that required to maintain the observed 
increase in body weiglu ofCalanus, whereas towards the 
end of the season the amount of algal food available wai 
insufncicnf for the needs uf the copcpoJs. Cushine con- 
cluded that dunng the period of abundant algal food, the 
oopepoib wan consuming algd celb at a rate frailer than 



their needs (Cushbig and Vucetic, 1963). Towards the end 

of the season, however, they were unable to obtain lufB- 
cient food tu maintain egg laying. He accused them of 
**superfluous feeding** (Cuihing, 1964). 

Marshall and Orr's laboratory studies on Calanus failed 
to give support to this indictment; in contrast they showed 
that the female Qdanus was an efficient egg-making 
machine with a rise in output as the ration of Skeletonema 
cells was increased (Marshall and Orr, 1964). 

Cushing's results imply that under natural conditions 
with abundant food supply copepods have very low assimi- 
lation efficiencies. Pelipa c' f l'>70) measured zooplank- 
ton feeding rates under natural conditions from the gut 
content and rata of digestion and also from metabolic 
requirements. The copepods included under herbivores 
in their Tables 1 and 2 need a dady ration of up to 200% 
body weight par day. the flgnres being very variable but 
distinctly larger for the rapidly growing nauplius and 
copepoditc stages. These values agree in order of magni- 
tude with the mean of Cttriilng*s determinations. However, 
the assimilation efficiencies worked out from Petipa's 
tables (though I am not clear if they are experimentally 
derived or assumed values) are bi the range of 80%, whidi 
agrees with the extensive work of Marshnll .nui Orr (I9SS). 
Marshall and Orr's values range from 0.6 to 0.95 for the 
assbniiation efficiency of Caknus fimardtkus fed on a 
great variety of diatoms and flagellates. However, their 
phosphate tracer method may slightly overestimate the 
ratio. Nevartheless, then Is considerable furflwr support 
fhnn the large number of laboratory experiments which 
are summarized in Table 3 for the view that copepods, 
even when passing food rapidly through the gut, can utilize 
it efficiently. 

Growth rate and gross growth efficiencies are similarly 
high for marine herbivores. Values of F/B published by 
MuUin and Brookes (1970) for two Pacific copepods show 



TABLE 3 Assimilation Efficiencies of Copepods from Laboratory Studies 



Spedet 


Food 




Mean(A/C)' 


Author 


Cakma fttimoKhicus 


Skeletonema cosiatum 


Phosphate tracer 


0.69 


Marshall and On (1955) 




Lmderia (old culture) 


Phosphate tracer 


0.58 


Marshall and Orr (1955) 




LauOtria (young culture) 


Photphaie meet 


0.98 


MaiihaUan4lOn(1955) 




Ckutoctm 




0.99 


llsniuaBiMlOfr(l95S) 




Chtamydomonat putmtOa 




<K9S 


Marshall and Orr (1955) 




Chromulimi pusiUa 




0.S0 


Mauhalland Orr (1955) 




FtHtUnium imchaldeum 




0.76 


Marshall und Oti ( !Q5M 




GymHodmium vililigo 




0.92 


ManhaUandOn(l955) 




Skeitiommm 


Nitrogen balance 


0.63 


Corner c/d/. (1967) 


Ctlamu heigoiandicut 


Set too 


Diffcicace rood-fecet 


0.82 


Comer (1961) 




fUtMnMiisp' 


DifTeieace food-feosi 


0.72 


OMHwera9i«> 




JfxHvMliSP- 


IiKUieiik fecal cootent 
Avenge 


049 
0.70 


Cenovar(l96<) 



Copyrighted material 



MOONDM V raOOUCnvrrV IN THE tEA 



77 



the expected variation with size and temperature. The 
tralUermuplhtt Mages weighing in the order of a few 
micrograms give P/B ratios of about 100 yr'' , while the 
adults, weighing in the order of 100 micrograms, give 
vilues of about 60 tt 1 5 *C md about 30 at 10 'C. Graeze 
(1970) quotes values of similar order for Acartia clausii and 
Centropagts ponticus of 0. 1 2 and 0.09 days' ' (44 and 33 
yr'' ) raqMCtively. There to veiy good agreement ganerany 
diat grOM growth efficiencies, P/C fC - consumption), are 
also hi^ for copepods. The index P/C is always strongly 
ag»Klependent, being much larger In the early, rapidly 
growing, stages Since most copepods appear to be reason- 
ably short-lived, the overall growth efficiency must there- 
fore be hi^. Comer ef of. (1967) gave a detailed budget 
foi Catanus finmarchicsis in ;erms nf hndy nitrdccn, sepa- 
rating the treatment of the growing stage from that of the 
adult stage. The aniount of total reaowce put into grotvtb 
by the former was 34%, while the reproductive output of 
the adult female was 14% of the amount of food eaten. 
Derelopmental and mature stages were approximately of 
equal duration, so that the growth efficiency over the 
whole life span of 10 weeks was, for the female, 24%. 
Mullin and Brookes (1970) provide exactly siniilar infonna- 
tion for the developmental stages of Rhinocalanus nasutta 
and Catanus hetgolanJicus paciflcus reared on two differ- 
ent species of diatoms, with growth efficiencies ranging 
from 30-45%, not counting the material incorporated in 
the cast skins. 

In most offshore waters, itie other marine herbivores 
and mixed feeders are in a mlnoilty compared with the 
copepods, neverthelfs';. beire orennisns of a similar size 
and longevity their growth efficiencies ought to be similar. 
Some of the pobltohed Russian work suggests that thb to 
indeed so; thus Grccze (1970) and Pavlova (1967) record 
P/B values for marine cladocerans ranging from 70-1 10 
yr'* . while Pietipe et oL (1970) give values ranging around 
25 yr"' for a variety of herbivores anil mixed feeders. In 
the inshore waters, where there is a large annual influx of 
very small rapidly growing invertebrate larvae, the produc- 
tion per unit of biomass is bound to be very high. At tlie 
other extreme, the relatively large Euphausiapacifkat 
studied by La*er (1966) and reviewed by MuOin (1969). 
produces 0.9 mg carbon m~' d~' from an ingestion rate 
of S.S mg carbon m~* day'' at a mean standing crop of 
1 10 mg carbon m~' . The calculated growth efRcleney Is 
therefore about 0.16 percent, and the P/B ratio 3.0 yr''. 

Productivity /biomass ratios are strongly dependent both 
on temperature and food supply. There is a natural ten- 
dency for biologists to choose to work in spring and sum- 
mer when both these factors are optimal so that it would 
not be surprising if a cursory survey ot the Uterature gave 
a bias towards hifM values. Mullln's (1969) review eon> 
tains an excellent summary table in which the season and 
location of the measuiements are recorded. Moreover, the 



text draws attention to the many dubious approxinutions 
and assumptions, the ambiguities and downright mistake* 
that are far from uncommon in this literature Taken over 
the year as a whole with allowance for age class distribution 
and winter starvation, P/B values in temperate waters might 
wdl be reduced to S-20yr~' aoeordingtothesizeof the 

OOMPARISONS BE1WEEN MARINE AND TERRES- 
TRtAL HERBIVORES 

Productivity indices of phnktcinic herbivores may now be 
compared with those of their terrestrial counterparts. One 
must here distinguUi between cold* and wirm-blooded 
terrestrial herbivores. Grasshoppers serve as a good example 
of the former, since there have been several studies which 
agree tolerably wofl. The asrimHation efficiency, as ni moit 
insects, is low, tfia values given for Mdanoplus (Weigert, 
1965) being tlMMilMSt at 0J7, while slightly lower values 
are gWen by Odnm ttwL (1962) and by Smalley (1960) of 
0 J3 and 0.28 for Orchelunum. The utilization of plant 
food by grasdioppers is therefore only half as efficient as 
the utilization of phytoplankton by copepods. However, it 
must be remembered that land plants are different from 
microalgae in their biochemical composition though the dif- 
ference might not be apparent in calorimetric measurements. 
Relatively indigestible material is r^uired for structural 
strength, for resistance to desiccation and perhaps also to 
defend the plant against excessive herbivore attack. Such 
refractory components will result in knv atdmllatioa effi- 
ciencies unless specially powerful en/ymes have been 
developed. Plant bugs, which restrict their intake to cell 
sap, perhaps alTofd a fUrer comparison with aquatic haiU- 
vorcs. they have assimilation efficiencies nf over 60% (Wei- 
gert, 1964). The growth efficiencies of insects similarly 
compare unlWounbly vridt those of copepods, as one 
rriif.bt expect on size criteria alone. Also, the more ey- 
treme range of temperature on land implies a greater pro- 
portionate reduction in productivity during the cooler 
months. Weigert and Fvans (1967) quote P/B figures for 
grasshoppers of 3-5 yr'' , an order of magnitude below that 
of marine herbhrores, and their figures for other heibtvorous 
insects are of the same magnitude. 

The larger, warm-blooded herbivores present a somewhat 
different picture. Many have high assimilation efficiencies. 
From the tables presented by Weigert and Evans ( 1 967) dear 
ntice and ground squirrels have efficiencies over 60%, spar- 
rows greater than 90%, but elephants, notorious for their 
fecal output, are only 33% efficient (Lamprey, 1964). No 
doubt choice of food plays an important part in optimizing 
efficiencies in higher animals, seed-eating birds, for exam- 
ple, being proficient in this respect, while symUonts may 
greatly assist in providing celhilase and other enzymes 
capable of breaking down otherwise indigestible materials. 



Copyrigliico r:ia:.chal 



78 



But whatever advantage warm-blooded animals may gain 
by these refinements, they more than lose by maintaining 
tiie body tampenture draws tint (rf tiw nimwiidingi. The 
inflvttildt mult of an over heated biochemical system is 
hi^ respiratory losses which depress the growth erficiencies 
well below those of poikilothemu. Generally, the P/A (A ■ 
assimilation) values for homeotheims He between 0.01S end 
0.05, only about one-tenth of an average poikilotherm 
value. The domestic pig, whicii ut all homeotherms must be 
regarded n hiving been deaigiied for higji productivity, and 
which has an assimilation efficiency of 76%, can bowt of a 
gross growth efHciency (P/C) of only 10%. 

The issue of outstanding iroportanoe is the ecological 
efficiency of marine planktonic herbivores, that is. the 
extent to which they transfer energy through the food 
chain. As I have shown, on the basis of their smaller size, 
higiier metabolic and feeding activity, and more efficient 
ratios of assimilation and conversion, they clearly qualify 
for a rating well above that of terrestrial herbivores. But 
whether these merits are in fact put to man's advantage 
depends upon two vital relationships. First, whether in 
marine ecosystems a high proportion of primary energy 
in fact passes through herbivores, and secondly, whether 
the further transfer to higher trophic levels is efficient in 
giving yields which ire Meful to nun. 

In terrestrial ecosystems, the amuum i ii primary energy 
passing through herbivores is surprisingly small, even if 
one includes organisms which feed on dead leaves and wood 
litter. As Table 4 indicates, herbivores rarely ingest more 
than a third of the plant tissue avallahle above the ground. 
Lvon where the proportion ot plants bcmg grazed is favor* 
able, as in naturally grazed grttdind. the primary produc- 
tion available to the herbivores is rather small and the 
herbivores themselves are poor assimilators of ingested 
energy. 



Intuitively, one tends to the view that since litter and 
detritus of pUnt origin are conspicuously absent from 
marine environments, the bulk of primary produetioa 
passes through the planlctonic hlfbivore chain. But if one 
attempts to produce a table corresponding to Table 4 for 
the marine enviroiunent, there are no firmly based obser- 
vations to support it. The reason is clear. For while it is 
relatively easy on land to account for the loss of plant 
material and tu trace its path through a series of organ- 
isms wliich can be kept under constant obseivition, to 
(race (he food web from microscopic plants through a 
sequential pattern of swimming organisms in a turbulent 
medhim is not at present possible. Instead, planktologists 
have made two alternative or combined approaches: either 
to rely on laboratory experiments or to erect models based 
on very crude and often aecond-luuid statistical data. Lab- 
oratory experiments on pelagic animals and plants are 
probably valid only insofar as they can be extrapolated to 
low densities of organians in wall-less contabien. As exam- 
ples of such problems, one can cite the difficulty experi- 
enced in obtaining copepod filtration rates similar to those 
hi nature (Marshall and Orr, 19S5:Comer, 1961) and in 

measuring natural metabnlic (Petipa, 1966) and reproduc- 
tive (Mullins and Brookes. 1 967) activities. Models and 
theories are, in my view, an even poorer siibstitnte for the 
relevant facts, though they may have a value as a "Cedenken 
experiment" provided that all assumed or cannibalized dau 
are critically assessed, clearly exposed, and correctly calcu- 
lated. 

The available literature giving indications of the fraction 
of phytoplankton consumed by planktunic herbivores lias 
been well reviewed by MuUin ( 1 969). Table I , colunm 6, of 
his paper records values between 0.0002 and 0.58 for this 
quantity, while the text cites one or two impossible results 
where tlie vahie exceeds unity! Restiicting tlie choice to 



TABLE4 Primary P i wlii i i t lu ii id Utiiatiow by H uhir w es In Tefrestrl<l gcosystems 



HabiUI 


Net Primary Production 
(kcal m"' ) 


Heibivorc Ingestion as hraciion 
ot Production At)ove;round 


Author 


S. Car'.ilina guss field 


1,075 


0.12 


Odum<-/o/. (1962) 


Michigan grau field 


1.360 


0.01 


Weiigert and Evan* (1967) 




6485 


008 


Teal (1962) 






0.38 


Lamprqr(l964) 


Uganda 


750 


Oj60 


FMfidct and Swaalc (1865) 


Managed range nuximuin exploitatioo 

l-'orcst 




0.45 


UmhetaL (1956) 


Coniferous 


2, ISO (litter) 


0.19 


Kitazawa(l967) 


Warm tempeiate 


5.650 (litter) 


0.28 


Kitazawa(1967) 


Tempeiale (Canada) 




0.05-0.08 


Bny (1964) 


Tmpeialt dedduoiM (AMadimdhMt) 


IMOlttOatis) 


0.0S6 


Relchto and CmOw (1967) 


VaeeMo-Myrtim-PlHMm 


3.030 {Miags and Utter) 


0.016 


Kactmaidc (1967) 


Pinv-wk-aldw 


5.060 (foUace and Utter) 


0.17 


Kacamaiek (1967) 


VMaloctep 


676gdqrwL(?}iaaiMt 


0.115 


-rtajaa(l967) 



Copyrigliico r:ia:.chal 



SECONDARY PRODUCTIVITY IN THE SEA 



79 



those ca&es where the calculation is based on the whole of 
tlie looplankton, or on the dominant oifuikm preient, 

thrrc remain several in the region of 0.25-0 5, mainly for 
temperate waters. The intuitive assumption niiglit also be 
drawn from Men»] and Ryther's (1961) observations tlut 

higher values '.vi1! apply to tropica! seas In this whole Add, 
new methods and more critically determined facts are 
badly needed. Turning to the question of food chain efTh 
ciency beyond the second tropliic level, the results arc ex- 
tremely fragmentary and no general conclusion seems at 
present ponible. Steele ( 196S. 1974) has cogently argued 
that in order to account for the observed high fishery yields 
in such areas as the North Sea, it is necessary to assume, not 
only high ecological efficiency, perhaps approaching the 
vahies which Slobodkin (1962) considered maximal for 
aquatic systems, but also direct food chams, with little 
branching, between phytoplankton and tish. Support tor 
thbvfew is afforded by the high growth emciencies of 
pelagic herbivores and carnivores, as for example in the 
tropical Sugtitii hispida which has a growth efficiency of 
0.36 on a nitrogen basis throughout iu life (Reeve. 1970). 
However. Reeve's statement that a large part of the marine 
food chain passes through secondary carnivores, such as 
chaetognatiis, would not be reconcilable with Steele*s views. 
Gulland (1967), in considering potential plobjl fishery yields, 
also supports Steele's argument that high ecological effi- 
ciendes are necessary. Yidds are likely to be particttlarly 
high where fish can short-circuit the food chain by feeding 
directly on phytoplanltton, e.g., sardine (Lasker, 1970: 
Ryther, 1969) or can recover energy from detdtiis, e^., 
mullet (Oditm, 1970). 

DETRITAL FOOD CHAIN 

When planlttonic organisms die, their remains join the feces, 
east dcins and various other particulate teaidnes as detritus. 

Detritus, together with its associated saprophytic organisms, 

constitutes an important source of energy and ultimately 
links the plankton food chains with those of the benthos. 
Another important source of energy frequently overlooked 
is the leak;fpe of soluble nutrients from aquatic algae, both 
planktonic and benthic (Fogg, 1971; Ignatiades, 1973; 
iChmlov and Burlakova, 1969; KhaOov and Fbienko. 1970; 
Sleburth and Jensen, 1^6'') The mode of utilization of dis- 
solved material is not understood, but its most probable 
fate is to became adsorbed on Inorganle particles and 
utilized by bacteria All these delrita! components, there- 
fore, tend to sink to the bottom and provide much of the 
raw material for benthic feeders. Obviously, witit increasing 
depth, the component of dead phytoplankton iriLR-ases as 
the component of living phytoplankton decreases, but below 
the eutrophic zone both plant and tntaud detritus diminish 
in absolute amounts. Furthermore, the quality of detritus 
becomes modified by the lost of the more biochemically 



active material as it sinks through the water column (Finenko 
and Zaika. 1970). Detritus Is fiedy utiliMd by many herbi- 
vore?, including copepods, while Ncctiliica, a saprophytic 
dinollagellate, often becomes extremely abundant at times 
when Urge algal Mooms are decaying, and then Itself be- 
comes a major souce of dead nrganic matter However, all 
detritus must originate from prunary production at the sur- 
face, and cannot be put forward as a source of food for 
zooplankton supplementing the photosynthetic production 
of a closed area, as Finenlu> and Zaika appear to suggest. 

Since phytoplankton and detritus are utDteed by herbi- 
vores and saprophytes as diey sink through the water column, 
it follows that in shallow waters the trophic chain will be ab- 
breviated and more material wiM become available to ani- 
mals living on the sea bed. Hence the productivity of the 
benthos is generally inversely related to depth, while the ef- 
ficiency of conversion uf plant material into zooplankton 
increases with the depth of the water. Qasim (1970) studied 
the primary production of a shallow channel in South India 
and tound a large surplus of plant material which was not 
required by the nther small numbers of herbhrores present 
The average yearly net primary production was 124 g C m"' 
yr'' of which only 30 g C m^ yr~' was required by the 
planktonic herbivores present in the estuary. Qasbn con- 
cluded that, in such situations, much of the phytoplankton 
must either die or be utilized directly by benthic inverte- 
brates and that this pathway could profitably be exploited 
by herbivorous or detriius<onsuming animals such as mullet 
and prawn. It is of course a general principle that shallow 
coastal waters offer the best conditions for benthic fisheries 
of all kinds, not only because of the ahbieviation of the 
pelagic food chain but also because such areas are frequently 
surrounded by productive marriiland which exports organic 
matter to the estuary fOdum. 1959, I960). It was the recog- 
nition of the potential of such areas tiiat led IBP-PM to em- 
phasiK their study. 

BIOHIASS OF THE MACROBENTHOS 

Russian workers have long been active in accumulating in- 
formation on the quantitative distribution of biomass on 
the sea bed, much of which is summarized in Zenkevitch 
(1963), and more It being fostered under ibp. Their data is 

given in (erms of erams wet weight m~^ of living or pre- 
served maciobenthos, including water, shell and other non- 
living matter. Table 5, abstracted from the above source, in- 
dicates the tremendous variation in biomass, and hence 
presumably in benthic production, in different seas of 
diallow to moderate dq»th. Leaving askle the obvious fea- 
ture that the biomass is greater in shallower seas, certain 
other trends can be readily picked out. it will be noted tlut 
the seas with prolonged ice cover have low benthos biomass. 
Although there is no clearly marked relationship between 
salinity and benthic biomass, in regions where there are well 



Copyriytinju rriaicrial 



80 

TABLE 5 Mtan Bioma»<^ of tht Macrobenthos {From Zenlwvitth, 1963) 



D. J. CRISP 





AppnniBiale 


Approximate 


Mean Biomaia 




Set 


Surface Salinity (%) 


Depth (Ri) 


Urn"') 


Notet 












liaxviiu am 




214 


100 


Pack icA HMMul in N £. 




25-2S 


110 


20 


£ flfiAntlu In gftwat 


KuaS. 












23-35 




50 


^Knrt uimmer ic^ frcp ocnrwl 




26-32 


100-200 


2-5 


ChnrI Uimmer icf frt^c t^ct\[-A 




15-26 


50 


100-300 


Short stiiTiTTier ice free oenod 


Baltic Set 










N. Gulf of Bothnia 


3^ 


((^140 


0.2 


S-7 in on till ice cover 


S. Gulf orioliinU 


4-4 


100-300 


12 




Gulf of FiMand 


6-T 


0-8Q 


57 




GuirofRigt 


6-7 


0-M> 


Jg 




Ballic. N. of 56° 


6-7 


100-200 


35 


AnaaraUe tfaao ufatar 


Baltic. S. of 56° 


7-8 


50-100 


60 




Belts and OresiMd 


t-2S 


7-30 


186 




Southern Soas 










Mick Sea 


17-19 


U70 


35 


Anaarobic daaplijfat 


Seaof A<ov 


10-12 


7.2 


310-400 


EmludiOK G. Ti|Hmg 


Gulf of Taganrog 


l-« 


4.7 


30-55 


Racalvoi R. Don 


N. C^spjun S. 




1 ijU 




Receives r\. voi^ 


S. Caspian S. 


12.5-13.5 


325 


30 


Anaerobic deep water 


Aral Sea 


10-14 


16 


16-23 




Atlantic and Mediterranean 










North Atlantic 


33-35 


14)00 (?) 


366 




Adriatic and W. Medilenueu 


35 


0-2JOOO 


185 




£. IMHMmHm lyirfMdM Si 


n 3$-}7 


0-2^ 


6 




'Bioaaaaa la aa iraaa wat wan 


Ikl. Teconvart 10 heal mT* mulMii 


ply by O.S-0.2 accoM 


llMlotlwwM«rM6f 


•Inml cootwil. 



raaiked hdoclines (the Centra] and E. Mediterranean) and 

stagnant bottom water (deeper parts of the Baltic, Bbck 
Sea and S. Caspian) the average level is depressed, even 
though the shallower regions may be rich. Shallow seas re- 
ceWing large riven (e^^ Sea of Azov, Northern Ca^ian) are . 

as rich as shallow ocean basins. 

The reduction in benthic biuniass with increasing depth 
is clearly established, not only by the work of Filatova 
(1960) and Vinogradova (1962), but also by that of Sanders 
el al. (1965). Despite the wide differences in the equipment 
uied and in the nomban of indlvidttala «Boo«l«d, wWch 
mukfs strict comparison impossible, the investigators agree 
that the density of animal life in the abyssal plains is less 
than fliat on the continental dopes by one or two ordan of 
magnitude, and is particularly sparse where the overlying 
seas are relatively infertile (e.g.. Sargasso Sea, Table 6). 

Bottom Bving species are divirible into (a) tlie epifimna, 

including free livino demer'sal fish and invertehrates (shrimps, 
whelks, etc.) and sessile forms living at the surface; (b) the 
infauna, comprising animals hidden beneath tlie turftce. 
Zatsepin (1970) further divides the macrobenthos into filter 
feeders which utilize suspended food from the water, detritus 
feeders wMeh oonaume material loosely accumulated near 
the surface and deposit feeders that utilize organic remains 
by ingestiiv the sediment itself. The abundance of each 



group can be related to depth and type of deposit. He diowed 

that, over typical areas of the Bannts Sea, the total biomass 
falls from 266 g m'* wet weight near the surface to 40 g ra'' 
at depths exceeding 325 m. With increasing depth the pro> 
purtiun of filter feeders falls while that of deposit feedSfl 
and detritus feeders rises Wart- significant, however, were 
the changes in leeding type with the character ot the de- 
posit. In coarser, gravelly deposits the filter feeders accounted 
for 70-80^ of all animals. Moving into the finer sand and 
silt deposits, epifaunal filter feeders almost disappeared and 
the infauna] filter feeders were increasin^y displaced by 
detritus and deposit feeders. Less than 209^ of tlw bentMc 
biomass was drawn from other trophic groups. 

PRODUCTION MEASUREMENTS ON MARINE 8ENTH0I 

The tn>phad3mainics of marine benthic organisms is known 

only from a few studies, some of which arc recorded in 
Table 7. Taking first the values of flu assimilation efDcienciet, 
those for browsing herbivores are about die sme asor 
slightly higher than those for in.sect herbivores such as grass- 
hoppers. The actual value depends much on the food source 
as Cai«feot*s (1967b) careM andysis of feedhig in Aplysia 
has shown, the softer and more delicate algae being preferred 
as well as being mon easily digested (Table 8). For the same 



Copyriyliicu iiiaior 



SECONDAfI V ^ROOUCnVlTV IN THE SEA 



81 



TABLE 6 Number) of Benthic Aiiimili par SquMt M e ttf from ModMatt to Qmt 0«plht, 

Stioinng Variation with Depth 



Sea Area 


Depth (m) 


Animals (m ) 


Observer 


E. Mediterranean 


1 00-200 


290 


Chukhchin(i963) 




200-1,000 


21 






1,000-3.000 


<2 




MagSw 


100-14NM 


521 


KMiiiaUav(1964) 




3.000-3,000 


lis 




KuiieUuMl 


0-50 


102 


K«net>ov(1963) 




50-100 


94 






100-200 


111 






200-500 


245 






500-1.000 


204 






ljm-2J0M 


26 




KE.fMlfe 


<4JBM 


2< 


Pilatava and Uvatwttio (1961) 


JavaTNnch 


6.000-7.000 


25 


Balyaav and Viaoiiidon (1961) 


W. Atlantic 


100-180 


1.790 


1V||l9aadlieliitne(t964) 


Off S. New England 


350-600 


1.170 




V>. A-.bntic 


Shell 


6.000-13,000 


9aiMlaf»tf«t(1956) 


Bermuda tiantcct 


Upper Slope 


6.00l>-23.000 






Luwer Slope 


1,500-3.000 






AbymliiM 


5OO-1.20O 






AbyiaipliiR 


M0»270 






Ditto SuganoSe* 


31-130 








140-850 





TABLE? 9Mand«vP^«dMetlonbvMariMB«n|hielnMfMmi1w 





PupuUtiun 




AuimiUtion 




AninHl 


rndoetiMdrT'') 


P/B(jrr') 


Effidenqr 


Aathor 


nemvores 










Lillortna Irrorata 


41lMalm~* 


0.7 




(Mum and SmaQey (19S9) 


l.itlnrina liltorra 


SOkcatm"* 


04 


0.45 


Guliiimc (1970) 


Litiorina planaxis 






0.4U 


North (1954) 


Apljnlt pimclalm 




7.3 


o.e7-a74 


Caiefoot (1967a) 


Cmiwvaa 










Namex btermit 






0«2 


Naa<196S> 


Daidmioais fromtoius 




18.2 


0.86-0.93 


QmrooM1967a) 


AfdUdorit psmdoaipa 




9.0 


052-0.93 


Carefoot (1967a) 


Suspension feeders 










Cardium eJule 


I.ISOg (wet wt) m'^ 

230 kcal m'' (?) 


4.0 




Zenkentch (1963) 


MyiUatter Untatut 


900 g (wet wO m'* 
180 kcal in~^(?> 


3.22 




Zealcevitch(1963} 




3Q0g(wet wt)m~' 


4.76 




Zaafeevitcli(1963) 




60 teal m~' (?) 








Modiolus demixsut 


16.7lMaa«''' 


0.3 




Kucndcr(1961) 


Tellino tenuis 


3.6 kcal m"* 


0.7 




TrevaJlion el at. (1970) 


Miu'd su^ension-detrinu faeden 










Pandora gouUktm 


6.2 g dry wl m~' 
25 kcil m ' 


2.0 




Sanders (1956) 


ScndkuUtrit/ilmta 




a6-0.9 


045 


HugtMs(1970) 


Sjmdnmym ovola 


377gwat wCm"* 
7Slualiii'*(?) 


1.0-2.05 




ZenkievJtch (1963) 


Depotii fecderi 










NtlMviliKlKir 


9.3 f. dry wt m"* 

37 kcal m'' 


116 




SaiMiin(l956) 


autnoUanaitUB 


1.7 f dry wl in"* 


1.94 




SaiMlen(19S6) 


YoUkSmttuk 


3.2gili)rwtn*^ 
ISkMlm'' 


128 




Sanden (1956) 



Copy righted maienal 



82 



O.J.CRI» 



TABLES Ikowdief Jiima4l«4p4«wp«wf>(»onlNffw^ 
(FroniGMif60t.1W7b) 





Order of 


AMimiUtion 




Alga 


Choka 


Kmciency {%) 


riiHismium cocciHfum 


2 


6-S 


7.3 


Kniewmorplm iiitttHiiaUt 


1 


>4 


7.1 


UIm ktetue* 


3 


75 


6j6 


Heum^koHla pbuHom 


4 


71 


%A 


Cryptopleura ramosa 


S 


71 


3.9 


Delessark sanguinta 


6 


45(?)* 


34 


Laminaria Jigitata 


7 




OA 


Oesmarcitia acuU-ala 


8 




0 



"f'/B calculaifd from (Vk- Wi)/y, (Wj • Wi ) x j65/t. where Wi = tnitial mean we^ht 

ind Wj = mean weight after t days growth 

^(?) indicalM mult* bwd on intufricieni materul iniciled. 



reason Ihe assimilation efficiency of carnivores is hi^, 
whereas that of detritus and deposit feeders, whose food is 
already highly degraded, is hlcely to be low. Haywood and 
Edwards ( 1962 ) for example found an efficiency of only 
4% for the freshwater mud snail Potamopyrgus ienkinsU. 
Furthermore the greater the depth at which henthic ani- 
mals live, the less readily assimilable is the food material 
and tlie lower its energy content. Allen and Sanders (1966) 
ihow that inch organisms have very large intestines for long 
retention of material andOWMdingly slow growth rates. 
Their productivity in consequence is likely to be of a much 
lower order than that of anfanals to which we are norniaily 
accustomed, but for obvious reasons no precise information 
is available. 

The values of P/B lor most oi the intcrtidal and shallow 
water species lie hi the region 1-S yr~' , not really diffierent 
from those of terrestrial invertebrates of similar size. Brows- 
ing intertidal penwmkies appear to have low P/B values, so 
also ham detrltua and deposit feeders, while those given 
for carnivores are relatively high as might be expected. How- 
ever, account should be taken of the fact that young stages 
of maibie tovertebrates are often hard to flnd and are not 
usually fully rcprc^fnted in samples, so that the P/B values 
of field populations may be too low. 

Marine benthic herbivores of temperate cUmaics fieedfatg 
on macroalgae are few in number. Like their terrestrial 
counterparts, they do not make serious inroads into the 
mass of algal vegetation that covers the intertidal and dullow 
sublittoral. The greater part of this vegetation must there- 
fore decay or be destroyed mechanically, entering the food 
chahi by way of detritus-feeding organisms. It is surprising 
that the rehitively soft tissues of the macroalgae are not 
more heavily browsed; perhaps the biochemically peculiar 
reserves or the presence of acids and phenolic compounds 
deter hitenshre attack. However, thoie herbivoies tfut Ihre 
by scraping and swecpini: rocV; siirfnces arc present in 
abundance-for example, the various groups of limpets, the 



littorinas. neritas and inMh;:!?, Tliese herbivores are clearly 
in the ascendant over the plants on which they teed, not 
allowing them to progress beyond the sporeling stage before 
they are cleared away. It is a surprising relationship (South- 
ward, 1956) since the evolution of some mechanism of 
herbhrore restraint would allow a much greater supply of 
plant material to grow on the rock and thereby permit a 
larger population of herbivores to be supported. The im- 
mediate consumption by the herbivores of the mimjte a^ 
aporelings as soon as they start to grow on the rock face 
suggests that herbivore productivity must be limited by 
food supply, and that strong competition for food and space 
must exist between individuals. This anfanal-4>lant relation- 
ship therefore resembles the balance between zooplankton 
and phyioplankton -except that the littoral herbivores are 
much longer Uved and slower growing than mlerociustacca. 

The most remarkable feature among shallow water in- 
vertebrates is the very high biomass and production of the 
populations of suspemion feeders. Secondaiy ptoductlon 
per unit area of such assemblages must be the highest in the 
natural environment. For example, the average density of a 
population consisting abnost exchisfody of MytUus edidb 
on the MurnMn Coast is given by Zenkevifch (1^6.^) as 5127 
gm'^. Assuming a 2-yr turnover (P/B = 0.5) Ihe pro- 
duction would be 2.5 kg m~' yr~^ or about 500 kcal m''. 
Considerably higlicr v.ilues of biomass have been recorded 
elsewhere with, presumably, a productivity several times 
greater. An interesthtg verification of the above figure is to 
be found m an older comparison of terrestrial and marine 
productivity by Johnstone (1908) in which he gives the 
average annual commercial yield from cultivated mussel 
beds in Morcambc Bay at 1 14 g dry wt. yr'', or approxi- 
mately 440 kcal m'^. Total production, including losses to 
natural predators, would presumably be somewhat higiict, 
perhaps in the order of 1000 kcal m~'. 

The fact that the production per unit area of populations 
of marine suspension feeders appears so high compared with 



oopy I lytiiC'u rnaicfial 



SECONDARY PRODUCTIVITY IN THE SEA 



83 



that of terrestrial and planktonic herbivores is really because 
the comparison it an ttnhir one. Suspension feeden grow in 

profusion whenever there are strong currents, so that the 
area which they nonnaUy occupy is only a very small part 
of the mt of m aurfice whfch supplies the primary energy 
on which they feed. Nonetheless they are probably in- 
triniicaUy efficient convertors of energy. They do little or 
no work in seeking their food. Unlike higher vertebrates, 
they do nut maintain an internal temperature, with result- 
ing: ficjt iDivb. but they nevertheless control their metabolic 
rate and activity effictently, so that it is acclimated to 
ambient tempentuie (Criq^ md Rltz, 1967; Wddowt and 
Bayne, 1971). 

MEIOBENTHOS AND MICROBENTHOS 

Two other groups of benthic organisms deserve mention, 
tnit laiaeiy because their importance has not been matdied 
by investigation. These arc the benthic mciufaun:i o r.sisi- 
tag of protozoa and invertebrates of the size range 0. 1 to 5 
mm. living inteiititialiy or on the surface of deposits, and 
the miLrofauna consisting of bacteria and other micro- 
organisms living within deposits. Both groups may play an 
important role in the recycling of nutrients that reach the 
sea bed. ui much the same way as bacteria and aoO micro- 
fauna do on land. Far too little is known of their significance 
in the tropic chahi, but from Wieser and Kanwisher*s (1961) 
observations of the uptake of energy by estuarine mud, a 
demand ofl 4-19 mg Cm"' h"' (UOOkcalm ' yr"' ) 
seems possible, liven higher values lor cstuarme shoals of 
425 g C m"' yr"' (4000 kcal m"' yr'' ) are recorded by 
Marshall (1970) while Mclntyre et al. (1970) for sandy 
beach conditions, estimates SO g C m'^ yr ' (SOO kcal m'' 
yr~').Tbey belleva the energy uptalce of the meiofinuu 
of intertidal sands to be derived from dissolved organic com- 
pounds percolating through the void ^aces and utilized 
first by bacteria which are then eaten by niterrtitial antaials. 
If this energy mute is capable of dealing with large quantities 
of material, shallow sands may play the part of natural per- 
cohting filters in brealctng down surplus organic waste. The 
land meiofauna indeed seems to be naturally tnlerant of 
lii^ organic loads and of other forms of pollution (Gray, 
1971). 

There are indications, therefore, that the meiofauiul 
chain may be particularly important in shallow water areas 
where the detrttal energy component is partkularly large. 
Encouragement of the meiofauna might also help in con- 
verting detritus into food in coastal lagpons. In managed 
prawn fisheries, for example, meiofauna might substitute 
the trash protein which is normally an expensive element 
rn the intlusiry A suitably managed mciofaunal chain might 
sumlarly miprovc mullet fisheries (Odum, W. E., 1970). The 
potential for improvement resulting from more rapid re- 
cycttng of detritus is well iQuatraled by the benefldal efliects 



of the introduction of Nereis divemcolor into the northern 
Caspian Sea (Romanova, 1960). 

A generation of fundamental study is required to duddate 
these processes. In addition to our vast ignorance of the 
activities of benthic microorganisms, tiiere are two other 
exciting areas ready for further exploration. First the work 
of Stephens (1963, 1964) on polychaetes and of the South- 
wards (1970, 1972a, 1972b) on Pogonophora has reopened 
Putter's old speculation on direct uptake of dissolved organic 
nutrients from the environment. These inquiries have been 
extended to other groups present in deposits (Stephens, 1968), 
io that the general significance to benthic trophodynamics 
needs to be assessed. Secondly, the role of the so called 
"thiobios" in releasing energy in the deeper anaerobic layers 
of aedimeat needs Investigation (Fcnchel, 1969; Fendid and 
Riedl. 1970). 

MARINE CARNIVORES 

1 have now reviewed the main types of herbivores responsible 
for secondary production hi the sea, and touched upon the 
great army of suspension, detritus and deposit feeders which, 
in company with other benthic organisms, clear up the fall 
of dead and dealing food that reaches the sea bed. As yet 
no account has been talcen of the terminal carnivores which, 
as has been shown, dominate the sea as plants dominate the 
land. 

Long before the advent of IBP, fish occupied the central 
pivot of marine biological research, and some effort was also 
devoted to the economically important mammals. But the 
bulk of this vast literature is less concerned with the place of 
terminal carnivores in the marine ecosystem than with the 
part their exploitation plays in the human economy. It is 
only Airiy lecendy thai studiM of fWi nutrition have been 
started and these have tended to he concentrated on freih* 
water fish which are easier to deal wifli. 

Table 9 Hita tiie uniformly hi^ vahies of aaaimilation ef- 
ficiency for a number of fish, freshwater and marine. Like 
most carnivores, fish are excellent assimilators, particularly 
of protein, with efRciencies of about 90%. SbnOarly, they 

arc efficient i-oiivcrt^rs of assimilated enet r;, into Hi'sli. hut 
the values of growth efficiency are of course dependent on 
age, as is bidicated by Table 10 for the Pacific aardbie. 

Pandian (1967) gives, for two species of fish, the exponential 
relattonsilip of consumption, assimilatioa, respiration and 
growth to weight, W. Both flsh give shnUar results which in- 
dicate that the first three variables rise as W*'-'" whereas 
growth increases only as W° \ Hence the growth efTicienGy 
Pyc must fall with increasing weight as W*'". Laslcer's 
data (Table 10) gives an identical relationship up to the third 
year of life but older fish put less energy into production 
than would be predicted by a W"''-^ ' law. Nevertheless, the 
above rdattonahlp, coiqiled with population statistics, might 
make it pooiUe to predict the food oonaunq>tion offish 



84 



TABLE 9 AMimitetlen EfRdtney in FMi 



S|Mciet 


Auunilatiun 
Efllcieacy <%) 


Notes 


nereicaoe 


Salytiriui fimtimilis 


90.3 


RecakuUled by HoMm (1967) 


Job f[9f,<!) 


Cyprinuf carpio 


89 






MttttoptcyprtHoida 


91.5 


cal wcl uxidatiun 


P.indun (1967) 




97.2 


Protein nilrogen 


Pondian (1967) 


OpMoeefMia urialui 


90.6 


cal w<t oiudatiM 


Pandian (1967) 




97.1 


Proteiii nitrogta 


PtauUan(1967) 


t,rpombtp. 


96-9B 


hottiBflitfagan 


Gerl(i]ig(l9S3.l9S4) 


Kpimphclus gullatui 


96.0 


Frotnn wlfoani 


Menzcl (I960) 


Plcuronecles platcua 


92 


caiorlM 


Biiketl (1970) 


SanHHoptcamOn 


90J 


Dfy wl (cccakiilitwl) 


Lnkcr(1970) 



from values of annual Hsh production. Growth efficiencies 
rather higher than those given by Luker for the active pel- 
agic sardine arc rfcordcJ fur the more lethargic Oat Hsh: 
14% for plaice (Peterson. 1918). 20% for 0 group plaice, 
flounder ind toibot (Muiler, 1969) ind 36% for young 
plaice and dab under optima! conditions (Edwards and 
Steele. 1968; tdwardterail. 1969). However, the rela- 
tion between ooMumption and production for wild popula- 
tions of fish is lilcely to l>e considerably lower than growth 
efficiencies measured in the laboratory since, in nature, 
growth will depend very much on feeding rate or "ration" 
and on searching activity. Mann (i%5) gives values in the 
region of 0 06 'nr populations of river fish. A factor of 10 
to IS is perhaps appropriate for converting fisli production 
into annual food requirement. 

Fortunately, fish yields are known from many parts of 
the world, and if these yields are sustainable and not a drain 
on the capital lesouices of the stock, they can give some bi- 
dication of total fish production, and hence of the significance 
of fish in the ecosystem. Gulland (1967, 1970) reviews this 
proUem and antoesat a flguie for iN North Sea of 0.2 and 
Oj6 t C m'' yr~' for demersd and pdagic fish nipectlvely. 



TABLE 10 Effect of Age on Comrtnion Efficiency (P/C) 
for Sardinopseaerules. Growth and Reproductive Output 
Included in Production; Assimilation Efficiency Assumed 
80 Percent throughout Adult Life (Laiker, 1962, 1970) 



Aie 


Walgbt' 


Food 


CooverikwIUilioor 
GiowdiEflkiiKyP/C 


EmlmjfuRle 




Yolk 


62.0 


0-1 


<20g 


Aftemia 


164 


1-2 


2(kS4g 


Artwnia 


9,S 


2-3 


54-106 g 


Artsmia 


6.75 


3-4 


106-140 g 


Artetnia 


3.S 


4-5 


140-I6S g 


Artemiu 


2.7 


5-6 


165-180 g 


Artcmij 


1.9 



'Weight given in gonad-free. fil-frce values. 



Steele (1974) assumed that fishing accounted for 80% 
mortality among demersal fish-the North Sea being a very 

heavily trawled area and 50''? aniens pelagic fbh. From 
total yields of 0.93 and 2.04 million tons fram an area esti- 
mated at S X 10* km' , employing Wtaiberg*s (1956) approxi- 
mation (I g wet wt. tlsh = I kcal) he obtained production! 
of 2.5 and 8 kcal m~' yr~ ' , which are close enough to 
GuUand'segtbnateg. 

FOOD CHAIN EFFICIENCY AND FISHERIES YIELD 

For the North Sea it is possible to construct an approximate 
scheme for the main energy chain, which may be typical of 
that of a cool temperature marine ecosystem. The representa- 
tion (Figure 2) tvas inspired by Steele's penetrattaig analytt 
of this ecosystem (Steele, 1974) though the treatment heie 
differs in detail. 

Figure 2 b divided bito a pelag^ food chahl on the lefl, 

based on primary production by microalpac and a bcnfhic 
food chain on the right, based on detntal energy reacliing 
the sea floor. The upper part of the figure talces prfanary 

production as its st artine point in the pelagic system and 
Aows the various sources of energy contributing to detritus. 
The secondary production by pelagic heibhores is shown 
to reach a value of 175 and 180 kcal m"' yr'' by two in- 
dependent routes. The supposed conversion of detriial 
energy by macrobenthic organisms is baaed on a very crudely 
approximated biomass of 20 kcal m"' , which is the order of 
magnitude found by Russian workers for the benthic biiK 
mass of fertile temperate sen. It will be seen that there is 
only just sufficient detritus to supply the macnihenthos, 
and therefore the energy available for meiobenthic and micto- 
benthic activity is only a small fraction of the total. 

The lower part of Figure 2 starts with the known fishery 
yields and leads to values, first of total pelagic and demersal 
list] production as outlined above, and thence to values oi 
the energy consumed by fish populations. Between the 
upper and lower sections of the figure the links are virtually 
unknown. However, it can be seen that the energy made 



oopy I lytiiC'u rnaicfial 



amMBMIV MOOUGTIVITV IN THE atA 



85 



Autochthonous 
WtmCoHmn 



Alloeftthonout 
Bmthot 



P-BOO (Microilgwl 



ID 



200 (OrtMi«tdO(«Mie| 



12) 



^-0 



Saoondwv 



(SI 



(6) 




ITS 



LwdD*rit, 30 

OaidMMroiwna 

Toul AvailaWt 460 
toSsnthos 



C-400 

_(iai 04) , 

0-30 U 




Tertiary 
Productiofk 



YMdioMan 



C- 120 



021 



(101 



C- 37.S 
^« 2:S 

7 (111 

2 



FIGURE 2 Energy (low hypothMt* for th« North Sm (in kc»l yr~ ). In ih* atiov* figur* anargy (low batwaan tropltk 
■noMn. but tfta diraetion of tha arrow rapraaantt tha logical darivatian of tt»a valuaa givM. ROt Mw diraetion of anaiw flow, 
from Mp to bMMm of Ad TiM douW* widtrliMd Miu« am bind on obiHVMionik 1^ 
do dfcuHWd u MlM^ili n , ddiOd Urn dotud Iwlw u i i iiiii oU in H— « IndhH moio ^midHw idlnlniWpg. In 



iavalt tt Itnltad by 
tmhidi if alwayi 



MidmiMio. 



(1> Fredtetton mIum taMd oo SlMimn NMtort (19801, SMlt (10B8). OtMit and Baird (Y961I. 

I?l Auumption that 20% of primary prcxJuctian is rataawd at di«olwsd organic matter (Panons and S«ki, 1971). 
131 A»umpt>on that 30% of diuolvvd photosy nthatic matarial incorporatad in banlhw bactaria. or in bactaria which an attachad to 
»tida« and enter the benthos. 
(4) AMumption that 7SX of mieroaigaa aatan by haibi»o n a. 
(0) 4 X diy «Ml|M valuaa of aoopiankion from Adiini^ VHOlBd hy SMto (1094). 
m riodn att eii /li l n wi 1 »mi « l ln iwMMd mU71at C l w i lo waldwl ai w laamiia m. 

17) P/C OC ffWrth flffflclMI9|f MMMMtf St MM* 

18) Animilation affieianey aaaumad 70X, faeat 30% af dOaMMIpllaii. (TaWdSk. 

19) Pure assumption, inaartad for complatanan. 

(101 PolayiL fnfi.ny mart-ilily ..iiurniid 60 V, nf total. 

(11) Oamarial (ifhing mortality aesumed 80% of total. 

(12) Growdt ifOilaway of Wd> papulation P/C takan aa 1/18 ONann, 1965). 

(13) BaiwWe Mow Utm at 100 9 iW^ - 20 haal wi-*. amatt HpMo frui WwiiaH wotfc (TaWa 81. 
(141 Pm fcr h tum twM Wteawa uliao m M mm 7U 

(Wl 



Copyriyliicu liiaiorial 



88 

TABLE 11 The Contribution of Different Typ«t of Saa 
Avw to Fith Produetion (RytiMr, 1969). Oc«ot Atm 





Type oi Scj 


Area 




Upwclliitg 


Coa&lal 


Oceanic 


Ttooentaga of ocns 








•KB, (a) 


0.1« 


9.9% 


90ft 


Mmary production 








kcal m"^ . r ^ iP| ) 


3,000 


ijOOO 


SOO 


I'icological (.'Hitiency pet 








Irophic level, (e) 


0.20 


0.15 


0.10 


Number of irophic leveli 








from plant production 








to lUi pwdwcUon, (n) 


IS 


3 


S 






J.* « lU 




l-iUi production 








lital m"^ yr"' (P,<;") 


270 


3^ 


COOS 


Total fish produi tmn 








lo' tons/year (Using 








Winbcrg's transfonnation 








Ikcal- UfidifMi) 








(341 aPie") 


98 


122 


lA 


Percentage of fiA 








production 


44« 


S4% 


0.7ft 



ivaflible by hcibivores and by macrobenthic producers lie 

not ereatly in cxces^s of the needs of the fish pupulatiotis 
that are supported by ihem. Hence no great part of the 
«nef|y flow pasan outside the main food diabi. There ap- 
pears to be an excess of only about 50-6(y"' of the energy 
used in fish production wliicli could be available to other 
petagic and bentliie cemlvoiw. The above flffiies are, of 

course, exceedingly spec.dative, but Ihev indicate that tlie 
tentperate shallow water marme ecosystem is clficienl in 
producing fittii^ orftniam oieAil to man. The food chain 
described would have a total efficiency of -{^^ with fuvi 
trophic levels, or 10% ecological efficiency at each stage. 

Lea is Icnown of other marine ecosystems. Rylher 
(1969) analyzed the probable relationships in three main 
types of open water situations. He supposed that the 
greater the fertility of the water and Hie greater its primary 
productivity, the fewer would be the trophic levels in the 
food chain and the more efHcient the transfer between each 
pair of levds. Thus, In rich upwelling areas (Table 1 1) fish 
such as the anchovy may feed in part directly on the phytfV 
plankton. The ecological efficiency of fcach step may be as 
high as 20%. Conversely in clear oceanic waters there may 
be multiple trophic levels between plants and termhial 
carnivores and each trophic step may be only 10% efficient 
The resull of this high gearing is that the upwelling areas ac- 
count for a very much greater potential of wofM (Ui pro- 
dnction than cither their area or their rate of primary produc- 
tion would indicate. Conversely, the deep oceanic areas with 
dear infertile water, despite their hnge extent, seem onlikely 



to provide a fishery yield oomparaUe With that of the ooastsl 
and upwelling r^ions. 

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habitat aspo|owvboiwawlbirMawiltioiilM]rclnBti.SHiii 

48 61-68. 

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oflfaehaWtat. 

aiecle. I. H. 19S6. Flant productiM on the Pladen ground. J. Iibr. 

Biol. Ass. UJC 33:1-33. 
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Univ.rMii.12Sp. 
Slatle^J.IL.aiidLE.Baird. 1961. MtttonttnliMHipftaiaiy 

production, chlorophyll and partindate eaibort. limnol. 

C-canogr. 6:68-78. 
Ste«men Nielsun. E. 1958. A survey of recent Danish measurementi 

of the organic productivity of IhO IM. Rap^ p.V. Qhh. iBt 

Explor. Mei. 144:38-46. 
Slap)mtt» G. C 1963. Uptake of organic material by aq tiatie inert*- 

hntaa II. Aceufflttlation of amino adds by the bamboo wwm 



Ctymrnfllii lorquaia. Comp. Biochcm. Physiol. 10:191-202. 
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DECOMPOSITION OF 
ALLOCHTHONOUS 
ORGANIC MATTER AND 
SECONDARY PRODUCTION 
IN STREAM ECOSYSTEMS 



N. K. KAUSHIK 



The extent of lecondaiy production bi moit ecosyiteins 

depends largely on indigenous primary production. AJthough 
the rate of primary production may be greater in streams 
than that in various lentic environments (Odum, 1956; 
Tominago and Ichimura, 1966), its magnitude is limited. 
Some of the important factors that adversely affect primary 
production In sttreami aie: unstable and sandy beds restrict- 
ing suitable substrate for phytobcnthos; torrential currents 
having devastating effects un phytoplankton; and turbulence, 
turbidity and shading reducing or eliminBting sufriigiit. That 
indigenously produced organic matter is generally not suf- 
ficient to sustain secondary production normally encountered 
in streams becomes obvious if comparison is made between 
the rates of gross primary production (P) and community 
respiration (R). It has been shown (Table 1) that in normal 
streams the P/R ratio is nearly always less than one and has 
thus Indicated that the bulk of the plant food material, 
which forrns the basis of the secondary production is not 
synthesi/.ed indigenously. Therefore must streams are iietcro- 
trophic, and obviously allochthonous oissnic matter is ini> 
portani for aecondaiy produetioo. 

DEGREE OF ALLOTROPHY IN STREAMS 

The role of allochthonous organic matter in stream economy 
trat suggested u early as 1912 by TMenmiann and dnoe 

then has been discussed by some limnologists (Hynes. IQ63, 
1970). However, the measurement of the degree of alio- 
trophy has been attempted only recently and by a few 

stream ecologists. Teal (1*557) attributed 76 percent of the 
energy at primary producer level in Root Spring, Massachu- 



setts, to allodithonous material. In a Georgian atrem, <6 

percent of the net primary cmisumer producfivity was 
found to have its origin outside the stream (Nelson and ScoU, 
1962). Similarly, bi UnetvOle Cieelc, Pennsylvania. It has 
been shown (Cummins ?f a/.. 1966) that the biomass of 
primary macroconsumers was almost the same as that of 
detrital macroconsumers. A study on Bear Brook, New 

Hampshire (Fisher and Likens, 1972), the only study that 
has itemized the nature of input in a stream, has shown tlut 
allochthonous organic matter accounted for 99.8 percent 
of the energy available at primary producer level, and that 
52.9 percent of this was in the form of particulate organic 
Utter and the rest as dlnolved oiguiic matter. 

AL LOCHTHCMKMJS ORQAMiC MATTER AS A FOOD 

SOURCE 

A perusal of the food h.ihjts of stream animals shows that 
members of all the important benthic groups consume plant 
detritus which in streams primarily consists of decomposed 
leaves and other plant debris of terrestrial origin. This has 
been shown for members of Plecoptera, Trichoptera, 
Ephemeroptera, Diptera, AmphipiMla and Isopoda— the 
groups that comprise the hulk of the biomass of secondary 
producers in streams. Studies on food habits of a broad 
spectrum of benthic groups (Minckley, 1963; Minshatl, 
l967;Hynes, 1961) amply show tlie importance of alloch- 
thonous organic matter. This is further substantiated by 
the flKt that there is a strong corretatkm between die dis> 
tribution of detritus and that of many members of stream 
benthos (Egglishaw, 1964, 1969). Even in a large river, like 



90 



OfGOMKMrnOW OF ALUXMTHONOUB OflOANIC MATTER 



91 



TAMJE 1 0«ts from Vwiow Aulhon Showing P/R RMhH 



Author 


Year 


Location of Study 


P/R Ratio 

(«Oj/m'/day> 


Odum' 


1956 


Ildiea Umi f EiiKland> 


0.1 to 1.1 






Lark Ri«w f Enriandl 


0.01 to 1.1 






White River, Indiana 








(ii) Zone of rCijovery 


3.2 






f E 1. 1 n^i p . 1 1 1 u ! I '.1 n 








\rir nnllutiful 


0.008 






outfall 








Potomac Ettmiy 


0.66 




1959 


ttouM Mwr tytMH 


0.2 ID 0.7 






(B sueamt) and other 








itreams in N. Caiolim 




Nelson and 


1962 


MiddlL- Oconee KliMtf 


0.1toOitf 


Scott 




Oeorgia 




Duffer and 


19M 


Bhw Rhnr, OkUioaia 


flMiilya4ia0i6 


Oorris 










1 1966 


AnkamlUttw, Japan 


O.StoOJ 


Ichimura 









'lactaidei faaiilia of odnr iMdiia diad by Mm airthoe. 



the Minouri, 54 percent of the ofgtnic matter iogeitecl by 

fish has been attributed to terrestrial "source's (Berner, 1951). 

From the foregoing it i& evident that secondary produc- 
tkm in itieum diould laigBly depend on aabnUabflily of 
allochthonous orpanic matter by stream animals. However, 
this is an area of work that has received iwgligible attention 
Cram aquatic ecologfsts. Haignwe (1970) hai Aown that 
Uyalella azteca. an amphipod, is unable to digest cellulose 
and lignin-like substances, two major constituents of leaf 
Biter. Amimflatian efRcienqr of. azteca for efan leavet 
W35 xliown to he only abuul 5 perciT.t, The overall assimila- 
tion efficiency of nymphs of Pteronarcys scoiti (Plecoptera), 
when maintained on a diet of leaf litter, it only 10.8 percent 
(McDiffett. 1970). This clearly indicates that most of the 
particulate allochthonoui organic matter is not readily 
ataibbla to stream detrithmet. bt this context it is also 
ntevant that many aquatic animals lack cellulase activity 
O^mov, 1972); and that the turnover of sediment by 
deposit-feeding invertebrates is very rapid (Gordon, 1966), 
indicating that only a small fraction of the total organic 
matter is directly available as food Dissolved organic matter, 
another nujor component of allochthonous input, may not 
be of mtidi conaequanoe in secondary production in ttieams 
unless converted into particulate organic matter. 

It has been speculated for many years that the dctrital 
energy source becomes avaibUe to detrithmes throuffi the 
microbes involved in its decomposition. At a later point in 
tlus paper the importance of microbes in the nutrition of 
stream benthoe wdl be discussed in more detail. It Aould 
suffice to mention here that factors controlling microbial 
activity during detrital decomposition also control the 



availability of food to detritivores and, hence, secondary 
production. Therefore, it is esaanUal to iwderatand factors 

influenoinp decomposition of allochthonous plant tissue, 
and those that control conversion of dissolved organic 
matter into particulate matter. 

CONVERSION OF DISSOLVED ORGANICSINTO 
PARTICULATE ORGANIC MATTER 

Processes involved in the formation of partkles from leaf 
leachates. a substantial source of energy in woodland strains, 

have been investigated recently by Lush (1970), and the 
factors outlined may be equally applicable to dissolved 
materials from the other sources. Leaves of two species of 
nuifit, Acer saccharrum and A. saccharinum, were placed 
in water and leached on a rotary shaker. To measure the 
rate of precipitation, aliquots of the leachates were removed 
at different time intervals and filtered onto a 0.4S /u pre- 
weighet! glass-fiber filter and teweipjied. Results (Figure 1), 
siiown as amount ol precipitate as a percentage ot the 
initial dry weigjit of leaves, clearly indicate fliat the forma- 
tion of precipitate depends upon leaf species or, in other 
words, the nature of dissolved organics. Lush (1970) 
thowied that such abiotic ftctors as turbulence, ffeeznig and 
the pH of water may also control the amount of material 
that is eventually precipitated. The initial pH of the water 
determines not oidy tlw amount of dissolved organic matter 
that leaches out of leaves and the amount that precipitates, 
but also the size of the particles that are formed. While in 
add watm the prec^tation is mudi ddayed and an abun> 
dant number of large particles are formed while neutral and 
alkaline waters result in smaller particles. In general, 
partides resulting because of abiotic lacton are smaller 




Copyrighted material 



92 



N. K. KAUSHIK 



than bOn in diameter. A few days al ter lurmation these 
prflcipttates are cdonizml by microorguiinM, bofh bacteria 
and fungi. Clumps resulting after biotic activity are larger 
in size and may grow to a few millimeters, depending upon 
the tttrbulenoe. There can be little doubt that these par- 
ticles are potential food for stream benthos (Egglishaw, 
1969; Brown, 1961). Since formation of the particles is in- 
fluenced by the nature of riparian vegetation and quality of 
the water, it is obvious that tfiese fa tors control the 
avallabiUty of food and hence secondary production in 
itreamt. 

DECOMPOSITION OF PARTICUU^TE PLANT ORGANIC 

MATTER 

Because of its importance in nutrient recycling, decomposi- 
tion of plant tisiues. tndudiiv leaf fitter, has been studied 
in detail by agronomists and woodland ccologists. It has 
been shown that the processes involved are extren>ely com- 
plicated. In contrast, aquatic ecologists have paid much less 
attention to these aspects especially in regard to the stream 
situation, where, as already mentii)ned, ti es? pro4;c<!ses are 
of utmost importance. In recent years it has been shuwn that 
leaves of dm. maple and wOlow, when placed in lotic en- 
vironmcnts, disappear much faster than thnsi- of oak and 
beech (Kaushik and hiynes, 1971 ; Mathews and Kowalczewski, 
1 969). These dtssfanOar rates of decomposition of various 

types of leaf may peifcaps be important in that th^ensuie 
a food supply in Streams for a lunger period. 

Obvioudy deoompodtion depends on the natuie of plant 

tissues that enter streams. Woodland ecologists have suggested 
that the rate of decomposition is controlled by such intrinsic 
factors as pH, water-soluble substances, C:N ratio, calchmi 
and nitrogen contents, total ash and constitutents like lignin 
and lannin. Temperature is another obvious but important 
Actor controlling decomposition. Ptdeadied autonui-died 
elm, alder, oak, beech and maple leaves, when incubated 
(Kaushilc and Hynes, 1971) in stream water kept at lO^'C 
and at 20 to 22°C, showed faster rates of decay at higher 
temperatures (Figure 2i,b). Similar results were also ob- 
tained when these leaves were placed in two southern 
Ontario streams. The effect of temperature on the rate of 
decomposition of plant tissue in soil has been studied ex- 
tensively and it hnsbeen shown tliat. althoiiph at higher 
temperatures breakdown ot cellulose and hemicellulo&e is 
aocderated, the effect is espedsliy marked on lignins (yftkk- 
man and Gerrctscn, 1031). Beech and oak leases have a high 
lignin content, and higher temperatures possibly accelerate 
decomposition of such plant tissues. 

Decomposition of allochthonous plant tissue nho de- 
pends upon the quality of stream water. Autumn-shed leaves 
of elm were separately incubated (Kaudiik and Hynes, 
1971) in stream water enriclicd with a nitrogen source only, 
or with both nitrogen and phosphorous sources, or in water 




*' 1 1. 

••r 




f i I « I • I • 



FIGURE 2 Percentage weigh! losi and protein content ein-i iUlmut) 
laavw kwpt for varioui lima inttrvati in itream water anrichad with 
only nitrogan or witti nitrogtn and phoiphorus. Mmo valuM t 95% 
eenfMMiM liniHi. M M« (c) M 10 *C «Ml(k) HI* lai «t 30 to 22 *C. 
WmMk and IV«m» ItVIk 



without added nutrients (control). The rate of decay in- 
creaasd bi the pfeaenee of an added nitrt^sn source and was 

further accentuated when phosphorus was also added 
(Figure 2a. b). Similar results were obtained with alder, oak, 
beech and maple leaves. Possibly other nutrients are also In- 

voKcJ, I: gglishaw (1968) has shown that htcakdown of rice 
grains in various Scottish streams was faster in those with 



Copyrighted material 



DECOMPOSITION OF ALLOCHTHONOU8 ORGANIC MATTER 



93 



higher cakium concentration. These results clearly show 
thai dinohed nutrients tai stream water are important in con- 
troDioB mieraUil bnikidown of detritus. 

DECOMPOSITION AND QUALITY OF FOOD 

Woodland eculogists (e.g., Bocock, 1964) have found that 
leaves decomposing on forest flours show an increase in 
nitrogen content. Similar observations have been feoerded 
for various leaves decomposing in aquatic environments 
(Mathews and Kowalczewski, 1969; Kaushik and Hynes, 
1971) (Fipire 3a, b). To determine tvhether tMs ineicue 
represented an increase in the absolute quantity of nitrogen. 
Kauafaik and Hynes (1971) incubated leaves for various lime 
palods in Stream water with and wMioiit tdded nutrients. 
The amount of nitrogen found in the leaves at the end of 
each sampling time was calculated as a percentage of the 
initial weif^t. The leaves kept in eniidied waters Aowed a 
significant iriL reasc in the absolute quantity of nitrogen; thIS 
increase was more pronounced when both the nutrients 
were added (Figure 3c, d). Uptake of exogenoas nitrogen 
was confined to a certain level that was attained in one to 
two weelcs depending upon temperature; once this level was 
nached only small further changes occurred. The level of N 
uptake also depended upon leaf species. e.g^ dm and maple 
gained more nitrogen that did oak or beech. 

Since the increase in nitrogen content of decomposing 
leaves is mostly in the form of microbial protein (Figun 
2c, d). this implie? (hat the quality of f<n^d available to 
benthos largely depends upon the capacity of plant tissue to 
support microbial populations. Thus, a stream receiving dm 

iriJ maple leaves probably provides better quality food than 
one that receives oak and beech. It may Iw noted that dur- 
iflg decomposition of allodidionous organic matter diere 
is only a slight change in the caloric value (Kaushik and 
Hynes, 1971 ; Mathews and Kowalczewski, 1969) but be- 
cause or mcreaseo proiem conient, accomposeQ organic 
matter is n food of better quality foi stream benthos. Since 
assimilation efficiencies are determined partly by food 
quality (Boyd and Goodyear, 1971) it b evident that 
microbial decomposition of organic matter should increase 
avimilation efficiencies by detiitivores and this can lead to 
hi|her seoondaiy production. 

DCCOMTOSmON AKID FOOD PREFERENCE 

Observations, similar to those of woodland biologists, that 
many invertebrates prefer to feed on certain types of leaves 
bve recently been recorded by aquatic biologists. Elm, 
maple, ash and alder leaves are preferred by various orga- 
nisms to those of beech and oak (DOlling, 1962; Wallace et 
d., 1970; Kaushik and Hynes, 1971; BSrlocher and Kendnck, 
1973). Many stream Invertebntes have been diown to prefer 
dscompoaed leaves tlut support microbial growth over those 



ELM 




FIGURE 3 H>\roq»n coment of «lm l»avBs kept for various tim* 
intarvals in (traam watar enriched with only nttrogan or with 

nitiogan and photphorui. M«an vakiM t 9SX oomMmm* limits. 
Wand Id M 10 'C and Ibl and Ml et aO toa*C (KaMblk 
aad Hyim, ItTII. 

that are freshly fallen and lack microbial growth (Kaushik 
and Hynes, 1971). An interesting study on the role of fungi 
in food preference by Gammarus pseudolimnaeus has 
recently been carried out by BSrlocher and Kcndrick (1973) 
They showed that given a choice between maple leaf discs 
and colonies of dlflerent Iqrpiiomycetes, orighuUy isolated 
from decomposbig leaves, tiie anbnds preferred ftmgi. 



CopyrigliiL.o na.u lal 



N.K.ICA1IMIK 



Amongst die fiiniti again they found an order of ptefeienee. 

Food selection in dniK'nann is not only influenced by the 
type uf leaf but also by the lungus it supports. It appears 
that leaves like elm, maple and ash are prefened by stream 
animals perfiaps because they, in comparison with beech 
and oak, are better substrates for preferred fungal types. 

Hynes(1961, 1963) has shown that streams gsnerdly 
support a lariMr Momass of benthic organisms in winter. 
The reason could possibly be that allochthonous organic 
matter becomes available as food during these months when 
the water temperature in most temperate streams is very 
low. Barlocher and Kendrick (1973) have shown that at 
winter temperatures aquatic hyphomycctcs (letradadium, 
Wcladium. AnguWotpon) tie able to colonize leaves where- 
as at higlier temperatures terrestrial hyphomycetes become 
important in leaf degradation in streams. Thus, it appears 
that microbial decomposition of leaf Htter, one of the major 
sources of allochthonous input in streams, is dominated dur- 
ing initial phases by fungi, especially aquatic hyphomycetes. 

DECOMPOSITION AND SECONDARY PRODUCTION 

Allochthonous organic matter supports a substantial bio- 
mass of stream invertebrates and initially this organic matter 
is not very attractive food for anunals. However, its nutri- 
tWe quality becomes enhanced because of microbial decom- 
position, and iJctnliviir.,.-> l ave the ability to select and feed 
on such plant tissues tliat support microbes, it has long been 
believed that lake detrltlvores derived their nouridunent 
from bacteria engaged in the decomposition of detritus 
rather than directly from organic detritus. The ability of 
chtronomid larvae to grow on Tiltcr paper to which suitable 
bacteria had been added (iviev, 1945) and ofSimulium 
larvae to grow on a bacterial suspension (Fredeen, 1960, 
1963) clearly show the nutritional value of microbes in the 
food of stream invertebrates. Recently it has been shown that 
the amnhipod, Hyalctla aziccu, is :ih!p to assimilate 60 to 90 
percent of the ingested bacterial biornass (Hargrave. 1970). 
Simibuly, many soO invertebrates are capable of growing on 
microbial diets (Burges and Raw, 1967). Selective feeding 
on fungus by soil-dwelling members of bnchytraeidae has 
been reported by OXkmnor (1967). Under laboiatory con- 
ditions Tnmoccrus is reported to feed selectively on fungal 
spores. Mycelia of Trichodenm and Phoma also serve as a 
diet for Collembola and tiwy diow very h^ growth rates 
when fed on these fungi (Hale, 1967). 

The processes that control decomposition of allochthonous 
organic matter also control the buildup of microbial popula- 

tions, and hence the protein content and the quality of the 
food that ultimately becomes available to stream benthos. 
Sbice allochthonoua organic matter supports a major part 
of the biomass of stream iiivertebrates, it is conceivable 
that their production should mainly be governed by the 
pi o c e sB B s involved in the daoomposltioii of allochthonous 



organic matter. Althougjh no study has att e mp t ed to 

directly elucidate this relationship, results from various; 
publications show the importance of sonw of the processes 
governing decomposition, and of the quantity of alloch- 
thonous input in relation to secondary production. 

Jewell (1927) observed that prairie streams, being almost 
devoid of imported organic detritus, support a sparse fauna 
as compared with savarmah and woodland streams. Streams 
in heavily wooded ai eat in Sweden have been reported to 
have more invertebrates than are found in simOar but open 
streams in Wales ( Babcock, 1953). In Morgan Creek in 
Kentucky, Mmshall ( 1968) observed that the stretch of the 
creek passing througti an area cleared of forest had decreased 
species diversity and fewer numbers of individuals. 

Not only is quantity of allochthonous input important 
but even quality can atlcct secondary production. Replace- 
ment of deciduous forests wttb ooAiferouswoodlaiid (TINb 
and Pi<■l^^l^ lias been shown (Huet, !9Sl) to have caused re- 
duction in benthic launa of nearby streams. Although Huet 
attributed this to the changed water pH and the toxins re- 
leased by needles. Kendrick (personal eommunication) 
speculates that the result was because of comparatively 
slower decomposition of the coniferous needles. Fidier 

( 1 97 1 ) and Triska ( 1 970) have sh own that most of the 
particulate organic matter that enters a small stream is pro- 
cesaed in the itrem. This prenmably depends upon the 
nature of particulate organic matter. Coniferous needles, 
having a slow decomposition rate, need more time for 
procesring and eventually consoinpthM by banthoa. Thus, 
there is greater chance that needles will be lost downstreun 
deprivii^ benthos of food and causing dacraaaed produ^ 
tion. 

Perhaps the only study that has attempted to show a cor- 
relation between the decomposition of organic matter and 
the standing stock of invertebrates in streams is that by 
Egglishaw (1968). He recorded that m Bine Scottish High- 
larul streams with varying Liileiurti eoncentTations, the 
higher the concentration ot Ca" and liCUj ions, the faster 
the rate of daoomposition of dead |dant tissue. The straams 
with faster rates of decomposition showed lareer standing 
stock of many invertebrates and presumably had Irigher pro- 
ducthrtty. 

It is evident from the preceding that the factors involved 
in the decomposition of allochthonous organic matter in 
Streams can hisve important ecological implications. Other 
factors being equal, secondary and tertiary production in 
streams depends upon the quality of organic matter. There- 
fore the manipulations of the ri^t kbids of detritus and 
microbes could lead to better fish production. Since microbes 
and detritus are primarily responsible for trapping nutrients, 
the more efRctently this is done and incorporated into re- 
movable secondary and tertiary production the smaller the 
quantity of nutrients continuing downstream, thus slowing 
lake eutrophication. 



W ALUWMTHONOM ORSANIC MATTI R 



96 



ACKNOWLEOGMENTS 

Imcnlenil lo Dr. Lndi foriloiriiigtlic meof nnpubliilMd tofoma- 
don from Ms thesis aad for critkslly going through the mnusciipt. 

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Drotininftholm 35:21-37. 
Bailocher, F.,and B. KtiiJrkk l'^'^? I un^i .ir.d food preference of 

Gammamt ptetUtoUmnaeui. Atch. HydrobioL 72(4):501-jl6. 
Bemer. L. M. 1991. UmaUiiy of Hw kwtr Mbmuil ii«tr. EeoL 

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^ m a^, N. 1972. CtebohydrsiM in CUnmomm, Cammtnu md 
HUM Trfchopisn lam*. Otkat 23:261-363. 

Bocock. K. L. 1964. Chtngei in the unounts of dry matter, nitrogen, 
eathon and entity in decomposing wunjijiid Icjf litter in rela- 
tion to the activi net of the soil fauru. J. ixol 62 273-284. 

Boyd,C. E..andC. P. Goodyear. 1971. Nutritive quality of food in 
ecolaigtcal tyttcmu AiA. Hydtobiol. 69:256-270. 

iMm, D. S. 1961. Tlw food of tfie l««M of GIJiMattd^Mim 
Md awlfr lAodM (Hettt) (biMem l|M«nofopien). J. Ania. 
BcoL 30:SS-7S. 

Bu/itet, A., and F. Raw (ed.) 1967. Soi Molonr. Academic ttm. 

New York. 532 p. 
Cummins, K. W.. W. P. Coffnun. and P. A. RofT. 1966. TkOfMc Mir 

tiou In a mnll woodland stream. Verb. int. Verein. the of. aitgcw. 

UnaoL 16:627-638. 
DOi^L. l962.DnAntiidcrTi•^Mlta•d«MldMt«wwUnM^ 

WMWihoden. Verh. Zool. BoL Got. WIen tOi-102:SO-«S. 
Dijfff:. W R , anJ T C. Dorris. 1966. Primary productivity in a 

southern Great Plains Jtream. Limnol. Occanogr 1 1 ; 14.1-151. 
Egglishaw, H. J. 1964. The distributional reUimniiups bv ;*ct. n the 

bottom fauna and plant detritus in streams. J. Anim. ivcol. 

33:463-476. 

Ek^tdmr, H. J. 1961. TlM qtmnlitedra ntadaniidp betMMi bot- 
tom loima and plant detritus in streams of difbrent calcnmi 

concenlraliun. J. Appl. Ecol. 5:731-740. 
Egglishaw, H. I. 1 969. The distribution of bentliic invertcbrafet in 

fasl-flovbing sircams J Anim. Ecol. 38:19-33. 
Fnhcr.Si C. 1971. Annual energy budget of a small forest stream 

eeuyttcm: Bear Brook, West Thornton, New Hampshire. Ph.D. 

dimeitaiion. Dartmouth Coiiqie, Hano««r> New Hamiiehire. 97 p. 
ndNr.&G..mdG.E. Likens. 197X Streim ooovMam: Otpnic 

cnersr budget. BioSci. 22:33-3S. 
Ficdeen, F. J. H. I%0. Bacteria as a source of food for MacWIy 

larvae. Nature Lond lh7 :%3 
Ftedeen, J. H. 1 963 Bactena as food for bUcMly larvae (Diptcra: 

Simuiiidac) in ubont(^onNai««idiiiaatnnltin«ns.GBn. 
i.ZooL 42:527-548. 
GaidBn,D.C. 19i6.1lMaffiM«riw4«|NMttlMlntpa6'C*wlr 
/iMitarii foiddi Oil Iho iniwtldal sadlmaMs of ■untiMe 

Hirhor. Umnot. Oceanosr- Il:327-33r 

Hale.W.G. 196 7. Collcmbola. p. 397-»ll /'i A. Burget and F. Raw 
(ed.) Soil biology. Academic Press, New York. 532 p. 

Hargrave, B. T. 1970. The utilisation of benlhic microflora by 
UyaUkazteca (Amphipoda). J. Anim. Ecol. 39:427-437. 



HosUn. C. li 1959. Studim of oxygen metaftoUim of stieame of 

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l ink.) Verh. int. Verein. theor j;:>-l-u. ! minol. 11:198-200. 
Hyncs, H. B. N. I%1. lite invertebrate fauna of a Welsh mcMintaln 

stream. Arch. Hydiobiol. 57:344-388. 
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Hyncs, H. B. N. 1970. The ccolo^iy of running waters. Liverpool 

Univ. Press .s.vs p 
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1727-1759. 

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298. 

Kaushik, N. K .and H. B. N. Hyncs. 1971. The fate of the dead 

leaves that fall into streams. Arch Hydrobiof hHi:4 ) 4^5-.": 1 5. 
Lush, D. L. 1970. Uissolvod organic matter in streams. M. S. thesis. 

Univ. of Waterloo. 78 p. 
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leaf Utter ■ad ftteoBtiilmiion loptoductioa in Rim TlmiMa. 

I. Ecol. 57:513-582. 
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11:124. 

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WMIace, J. B., W. R. WowUI. and F. F. Shettetger. 1970. Biaafe- 
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(Plecoptera:Peltoperiidae). Ann. Entomul. Soc. Amer. 
63:562-567. 



CopyrigliiL.o na.u lal 



NUTRIENT CYCLING 
IN FRESHWATER 
ECOSYSTEMS 



O. W. SCHINDLER, D. R. S. LEAN, and E. J. FEE 



ABSTRACT 

Fhw* in lotic or neUiodolafy haw oflMi cuued enoncous 
condusiuni to be drawn from chemical axperhnants in tmk water. 

Some cxamplM rollow. 

ITic jcid molybdjlf itu'|!'.<jJ u.;is fnumi In picjtly uvcrfslirnatc 
phusplule cuncendations in many lakes. Phosphorus found to 
be hydrolyzcd from organic lutelaiMet te lllleicd lake water hy the 
add moiybdate leacent. 

The ■*€ bottle Moonay tednriqu* ii often mi*an>IM to 
nianainnent qacttiont. It wm demontualed thai while lake 227 
became eutrephic as the reiult of addiiloni ot phosphorus and 

nitrogen bioasuys indicated Ihjl Lar'iMii '.vjs !_:riiiinr ilir Mii-haUt 
much of a lypical Jjy. Carbon limitatiuii wjs ihc ris;il( i>!, Tather 
than Ihc cain'j i:r, ^iitrdphicalKin. In spilt ni low carbon conccnlra- 
tkins, cfiougli CU, was able to invade the lake from the atmosphere 
to allow algal blooms to develop. Comparisons witb data Trom tbe 
Uttientlaa Greet Lakes indlcaie that ibere it no possibility of car- 
boa Kmilaiion being of any significance to entroirtiiGation manage 
meatinthoeewatet*. 



INTRODUCTION 

The futility of the tndltianl approach to nutrient itudies in 

fresh water, i.e., the measurement of nutrient concentrations, 
has been soundly demonstrated during ihc past decade while 
IBP Itudies have been in piogre«> It it paiadoxical that 
biological invesdpators. while attempting to make precise 
measurements of rates of movement of one element, carbon, 
dirough Motie components trf" the aquatic ecosyitem, have 
used only concentrations, i.e., pool sizes, of other nutrients 
to characterize acqualic ecosystems. To use sudi informa- 
tion to chef acterise the role of nutrients is equivalent to 



using alpal standing crop as an index of biological produc- 
tivity. In some circumstances it may give useful informa- 
tion about the dynamics of the system, or it may tell 

nothing at ail 

Several new approaches to nutrient cycling have ansen 
during tiie time of the IBF studies. Some of these appeeied 

early enough to be incorporated into pr>it;rams; other tech- 
niques show promise, but have not yet been fully tested, still 
others have been oveiloolced nearly completely. The purpose 
of this paper will be to examine some of the approaches to 
aquatic chemistiy, and to expren some opinions ahnut the 
viability of these approaches as appHed to ecosystem pro- 
ductivity. 

Some e.xceUent examples of tlie impotence of the tradi- 
tional approach to nutflent chemistry have been afforM 

by the recent controversy over limiting nutrients (Likens, 
1972). Althougli most limnologists believe phosphorus to 
be the element limiting phytoplankton production and 
abundance in the majority of freshwater ecosystems (Hutcb' 
inson. 1957) and also responsible for the majority of eu- 
trophication problems (VoUenweider, 1968, Anonymous, 
1969), their evidence does not appear to have convinced 
legislator*; and industrialists in the United States. It is para- 
doxical that antagonists m the controversy have often used 
tlte same data to support their arguments, e.g., the con- 
centration of molybdatc-reactive phosphorus. Much of the 
following information bears on the problem of interpreta- 
tion of such data, since it is bdieved that many of the same 
errors have been made in attempts to interpret the effects 
of nutriiHits on biological productivity in fresliwater eco- 
vstems. 



^L.(..y I lyi lied material 



NUTRIENT CYCLINQ IN FRESHWATER ECOSYSTEMS 



97 



NUTRIENT BUDGETS FOR LAKES 
Phosphorus 

The monograph by VoUenweider (1968) presents strong 
evidence that the quantity of nutrient nipplled to a lake, 

and not nutrient concentration, :? 'he factor of importance 
in assessing eutiophication. A later theoretical paper (Vol- 
lenweider, 1909) elaborates the dynamic aspects of tiiit 
conclusion. The result has been a convincing condemnation 
of phocpborus as the primary villain in eutrophication. 
Sadly, theie are a large number of peisons who do not 
recognize the superiority of this approach over older, static 
conMpts like Sawyer's < ! ^47) Limits. More about enoia 
in concentration-based approaches will be presented below. 

For studies described to date, estimates of phosphorous 
input have ranged from 0.016 g P/m^ year (ultraoligotrophic 
Char Lake in the high Arctic) (Schindler et al. , 1 974b) to 
nearly 20 g P/m' year (hypcrcutraphic Grcifensee, SwitZp 
erland) (Pleisch. 1970). Corresponding figures for nitrogen 
range from 0.1 to 45 g N/m' year. No input data are avail- 
able for the extremely productive lakes of central Africa 
and Norih America but hydrological and gcolnpical diffi- 
culties may render this impossible. The addition ui phus- 
phofUB and nitrogen appear to cauae eutrophication under 
any climatic regime, even in the high Arctic (Schindler el 
at, , 1974a). Predictions relating the trophic status oi lakes 
to nutrient input and mean depth (Vollenwelder. 1968: 
Anonymous, 1969, Vol. 2, fig- 3 I ) appear to be re- 
markably accurate, and it would be pointless to discuss 
them further here. 

The warning bv Rigler (196f», 1968) that the standard 
acid-molybdate technique may overestimate orthophosphate 
concentrations bi natural waters by 10 to lOOX has largely 

been overlooked, and most investigators still rely heavily on 
this technique. More recent work (Chamberlain, 1968; Lean, 
1973a, b. c) has demonstrated that colloidal substances In 
lake water, mostly of apparent molecular weight > 1 0'' , 
play a major role in aquatic phosphorus dynamics. Our le- 
cent unpublished work has shown that the acid-molybdate 
technique hydrolyses phosphate from the above-mentioned 
colloidal substances, causing considerable overestimates of 
phosphate in many cases. It has been found that true ortho- 
phosphate concentrations may be less than 0.1 pg/hter,* 
even in eutrophic waters (S. Lcvinc, unpublished data). The 
relative importance of colloidal material vanes greatly from 
one water body to the next, however , and in some instances 
reasonably accurate phnsphaie results may be obtained With 
tiie acid-moiybdate test. 

if the role of the phoephate "pool" in fresh waters is to 
be evaluated, concentration, temperature and demand by 
phytoplankton must be considered. We have tound rate 

• True oithophosphaie tont-enirations may \x estimated with 
rcavmabk- jccuracy by bl>>.>^sjy iKigler, lM6),orty iSOtOpe 
ptrtiiion using sepludex (Lciin, 1973a). 



constants for turnover of phosphate in natuial trcsh waters 
langbig over S ofderi of magnitude. On the otiier hand. If 

the phosphate demand of the sestonic phcspluniT.is priol. 
wiiich is a crude measure of phytoplankton demand, is 
consklefed, total lange is lethioed to 3 orders of magnitude, 
(egaullc^ of trophic status of the water body (Table 1). 

The extremely small phosphate pool must be rapidly and 
continuously replenUhed in order to maintahi even short> 
term stability in most aquatic ecosystems. Recent work has 
uncovered two important biologically mediated mechanisms. 
Lean (1973a, 1973b) found that when radioactive phosphorua 
vras added to unfiltered lake water, most was rapidly taken up 
by phytoplankton and bacteria. Within rainutea, some of the 
radioi^hi^sphorus was excreted as PO4 , and some was traa^ 
I'erred tu the high molecular weight colloid described above. 
The colloid was not a direct source of phosphorous for 
phytoplankton. When phytoplankton were removed from the 
water by membrane filtration there was no movement of 
phosphate to the colloid, suggesting that the biota, rather 
than chemical factors, were responsible for the process. Pre- 
liminary evidence suggested that a phosphorylated algal or 
bacterial excretory product, of molecular weight about 250, 
was produced which bound to the colloidal material, re- 
leasing PO4 from the colloid in the process. The mode of 
operation of the mechanism, and its evolutlonarv signifi- 
cance, are obscure, but regeneration of piiosphate phos- 
phorus is poMible via thia pathway, as a supplement to PO4 

excretion. Both freshwater alp.ae and bacteria are capable 
of releasing wch excretory products, as well as orthophos- 
phate (Lean. 1973a,b,c). The seston takes up and reteaaes 
phosptiorus cumpounds at :i very high rate. The direct re- 
lease of phosphorus from ultraplankton is the most impor- 
tant factor in tite rapid turnover of this dement (Lean, 
1973a). 

Paten (1972) found that most of the phosphorus ex- 
creted by zooplanlcton wasin true phosphate form (Peten 

and Lean, 1973). While this is contrary to many of the 
conclusions of earlier workers, there is a logical explanation. 
Psten found that excreted orthophosphate waa rapidly 
taken up by bacteria in the culture flasks. Since incubn- 
tions by earlier authors lasted several hours, it is likely that 
the bacteria may have taken up the excreted phosphate and 
then been iiKluded in analyses for dissolved organic phos- 
phorus, due to their small size. Haney (1970) found that 
zooplankton in many fresh waters graze from 10 to over 
100 percent of the phytoplankton standing crop per day. 
If assimilation rates for zooplankton are 10 to 90 percent, 
as indicated in the literature, zooplankton excretion is 
anotiier important source of pho^hate nipply. 

CariMNi 

Cycling of carbon, where important chemical reactions com- 
plicate biological processes, is also poorly understood. Once 



D.W.flCHINDLSIIitaL 



TABLE 1 Tuvmwtr Tlmw, R«M OofHtami, ■nd Flux Rmm tar niotphonn in i Variiiy of NMml WMMt. Ml 
from the Upper Euphotic Zone, from June, July, or AugilM.Tra«Oi1lM|riMt|riwtlCanMnlr«tiamWmOMrii^ 
botofM Partition Uitng S«phad«x (Lmii. 1973s) 



An 



Uke 



Chariic(cri7ation 



Tolal PO4 Rale 

i>iti. PO4-P Conitint 

n*.»«g/l> (Mg/I) (k, min"') 



239 



227 



228 

Chiu Lake 



RCMltttC 



Red Rivet 



Precanibnati Shield 10 
Oligotrophic 

N. Tcmporale 

Preciimbiun Shield 8 
ArtiflciaUy eulrophleil 
N. Temperate 

Precambrian Shield 7 

Ultra-utigottopllie 

N. Temperate 

Limcitone 3 
Ultra-olifOtrapUc 

N. Polar 

Mofine Bay 40 

Ultn-oliiotroplnc 

N.PoUr 

Fertile cley ISS 

Valcjriiwr 

N.Tnnpente 

•n«Wd,^gricMlf»ei 



Flux Setlonic 
(dg. PO4 P/mift) (P.in/I) 



Mux 

Oig, PO«-P/wi> Water 

Sestonk Temperatim 

(P/min) rC) 



O.OS -0.12 



0.10 -0.26 



0.0s -0.013 



0.60 X 10 



0.26 X 10' 



-a 



0.63 X 10 



,-3 



151 -0.86X10'^ 2.6X10' 



IS 



0.22 -31 X 10"^ 0.6S X 10" 



37.7 -0.70 X 10"* 0.26 X 10"* 1 



50 



0.20 X 10" 



0.33 X 10 



11.34 X 10~ 



0.26 X 10 



0.52 X 10" 



21 



0.17 X 10 ' 24 



17 



1.0 



-1.7 



-20 



again, proper consideration has not been paid to kinetic as- 
pects of the cyde. Biologistthaveeonoentfated their efforts 
on the measurement of one rate constant, the uptake of dis- 
solved inorganic carbon (Die J by phy toplankton. and on 
the fneasuKmeot of pool sIzm, i,e., bicarbonate, lesloiilc 
carbon, etc. The mode and rate of leplenWunent of DIC 
has barely been considered. 

Most of our knowledge of chemkal kinetica affeeiing 
DIC has come from chemical experiments with pure solu- 
tfama of inorganic chemicals (Kern, 1960). Recently, com- 
plicatlom have been found which may signlflcantiy affect 
chemical equilibria. Ion-pairing has been known to affect 
critical reaction rates for some time (Wangcrsky, 1972; 
Wigley. 1971). At least one author <Wet2el, 1972) has sug- 
gested that chemical reactions in natural waters may be slow 
enough to cause freshwater phytoplankion to be carbon 
limited. 

A second shortcoming of our knowledge of carbon 
cyeUflg has been the lack of reliable information on in- 
vasion of carbmi dioxide into natural waters. This sdmltted- 

ly difficult problem has been a major stumbling block in 
evaluating the claims of several investigators (Lange, 1970: 
Kuenuel. 1969; fUtnetaL, 1970) that the alleviation of 
natural carbon deficiencies by sewage additions has caused 

many eutrophioation prohlenis Our studies ot" nutrient 
balance in natural oligotrophic and ardlkially cutrophicd 



experimental lakes have allowed us to obtain some insight 
into the above problems. 

In natural lakes of the Precambrian Shield, and in other 
areas, the concentration of dissolved COj gas is usually 
dlghUy above atmosidierie cquURwhim, pf obably due to 
regeneration of the jns by decomposition of both autoch- 
thonous and allochthunous organic matter in the water 
and aediments. On the other hand, in some hi^y eutrophie 
Inkes, the partial pressure of CO; in the eiipbntic /nnc may 
be far below that of the atmosphere, due to algal demands 
on die Dtr system and tiie anall poob of bicarbonate and 
carbonate- present (Figure 1). Such deficits do not exist 
in any oligotrophic lake, nor do they exist in most bicar- 
bonate lakes at temperate latitudes, including the St. 
Lawrence Great Lakes. This lack of a partial pressure deficit 
indicates that there is no significant denund on the UlC 
reservoir by phytoplankton, i.e.. they are In no way carbon 
limited. 

it is noteworthy that the carbon deficit in Lake 227 is 
more extreme than in almost any other lake studied, in- 
cluding some where carbon-limitation has been "proved." 
More detailed information on carbon cycling in this lake 
is instructive, therefore, since it is possible to obtain in- 
formation on carbon dynamics under perhaps die most 
extreme conditions anywhere in nature 

Dissolved inorganic carbon in Lake 227 before fertiliza- 



Copyriytiicu riiaierial 



NUTRiffrr cvcuNo IN frnwi wA TCT icomnMi 



09 



• LAKE ERIE. IM ICCIW OAT* REPORT) 
LlOOMIMIli^TIl 




muHti 

• MMIlbl 

tropMc takes. All graat ItkM arc 
ri>0«vn on tfve (UlrophiC graph. 
Pqq^ >i c«lcula(»d froin ■Ikalinity. 
pH and Mmparatur* or from total 
COa.|lM and taanfMratura (Lakat 

317 Md 239 only) wino 
MRtt of QmmIi m« CMM IIMBt. 
Char and Mwwtta IMm, M 7S 'N. 
lat.. are ie*-eovar«d for all but a f«w 
waaks o< tha pariod shown. Od«ar 
natural oligouapliic lakaa aMminad 
I annual 



T — I — I — r — I — I I [III — I — I I I I I I I ■ I I I I I I I I I I I I I * I I 

» ezftlft «s s istftls »» s isis(» IS a 
•MY I JUNE ■ JULY ■ AUGUST I SEPT I OCTOeER ' 



Uon, and bi similar lakes in the Canadian Shield, was 
ulually SO to 150 /uM/liter in midsummer, at pH's or 6.5 
to 7.5. A quick calculation reveals that the DtC reservoir 
bdieiefore 10 to 40 times smaller than in most lakes of 
economic importance. Yot by adding phosphate and ni- 
trate to Lake 227, we have been able to increase phyto- 
pliiiktfmitaiidingerop(iidiloro|ilij^a)fn>m I toS to 
lOO to 300 , i.e.. if is now highly eutrophic. 

In its eutrophic state, Lake 227 shows many symptoms 
of tt>«alM eaibofl limitation. Euphotic zone pH is over 10 
in midsummer, with DIC of about 4 to 10 ;jM/1 at midday. 
Under such conditions, gaseous COj is a mere 10*^ pM/lt 
six Ofden of magnitude Mow atmoapheric saturation.* 
Under such conditions, production is extremely low ant! in 
bottle bioassays response to nutrients other than carbon is 
aegligiUe (Figure 2). These cireumstances have been caused 
by the algal increase due to fertilization of tlic lake with 
phoq)honu and nitrogen, it is clear tiut bottle bioassays 
do not necessarily give useful Information about what mi* 
trient has caused eutrophication problems. They merely 
tell what nutrients are limiting at the time of the assay. 

Consideration of dhimai CO] and 0] dynamics in Lake 
227 reveals some interesting facts. At dawn the midsummer 
DIC concentration is usually SO to 60 ^M/liter. This is de- 
pleted by algae to 10 /uM or less in the next two hours, in- 
dicating photosynthetic rates similar to a healthy sewage 
lagoon (Fipiire \) Very little algal "production" takes place 
during the remainder ot the day. 

* IM( sp.vics jnd Pco, calcul.itcd from total OIC, pH and lake 
lempeuiure, using the conttitnts ul' GaireU and Christ (1965). 



Nighttime regeneration of Die and consumption of 0} 
is equally instructive, particularly if coupled with sealed 
dark-bottle measurements. The in situ change in concentra- 
tion dufing night is due to respiration plus invasion from 
the atmosphere and hvpolimnion I'haf in the sealed bottles 
is due to respiration aiunc, liicrclorc invasion may be cal- 
culated by diffeieooe (TiUe 2). Aaiuming that invasion 
during daylight is equal to that at night, the supply of ear* 
bon via this source can be highly significant. 

Calcobted CO] exchange it several times that for wtygen 
due to the fact that chemical enhancement, i.e., the hydn^ 
tion of invading COj , keeps the partial pressure of CO} gas 
in the lake low (Hoover and Berkshire, 1969). The observed 
enhancement factor agrees reasonably well with theoretically 
calculated ones (Schindler ei ai, 1972a; Emerson. 1974), 
but fwtiier work is needed. 

The annual carbon budget of Lake 227 is interesting, 
wtien compared to that of an oligolrophic Canadian Shield 
lake. A high proportion of the annual carbon faicoroe comes 
from the air (Table 3). The lake is slowly correcting its own 
carbon deficit, with an increase in carbon content of the 
water column averaging 35 percent per year. While limitation 
of phytoplankton pr . Jik ikm: by carbon IB apparently pos- 
sible in such a lake, algal standing crops are many times de- 
sirable levels before the deficiency becomes serious. More- 
over, a lake appears to be able to correct its own carbon 
deficiency from the atmosphere, i.e., the deficiency will be- 
come less pronounced ttom year to year if inputs of phos- 
phofusand nitrogen remain constant. 

When D!'*C is added to lake water containing phytoplank- 
ton, it accumulated on the colloidal fraction much as ^'P was 



Copyrighted material 



100 



O. ML CCMHIDtifiR ttiL 



FIGURE 2 Rt^MDM by ptiylo- 
pltnkton taktn from Ltk« 227 
(tM Figure 1) at midday to ■ 
variaty of light and nutriant co<v 
tfitlom. All MinpiM war* run in 
• liflit inmbaitaf •! apWiMiion 
liiiii iw iM W. AMMom «f iw- 
trianu v»ara int/l of PO4-P, 
BO^g/l NO3-N, aod I.OOWl o< 
HCO3 C. From 
Faa. 1973. 



n 

^ 12 
1 

8 

r 



2< 




IT JULY 1972 



I5* 



05 



— I — 
06 



09 



(Ly/minJ 



fouml to do. Binding of carbon to colloids appears to be much 
4ower than phoaphonis, with equilibrium conditiom reached 
after several days, instead of in minutes, S;i far tk? investiga- 
tions of the role of this colloidal fraction in regeneration of 
DiC have been made, but the fraction cannot be utilized by 
phytoplankton directly (Lean and Schindlcr, in prep.). In 
Canadian Shield waters, colloidally bound '^C appears to be 
reiponsibie for the conectJon for fOtntion error propoaed 
by Arthur and Rlgler (1967)(Schindler etoL, 1972b). 



CARBON LIMITATION OF PRODUCTIVITY 

In recent years a claim that carbon added with sewage is 
responsible for the eutrophication of many natural waters 
(Kuentsel. 1971) has confused die eutrophication iasue, 
causing delays in critically needed anti-phosphor us legisla- 
tion. Few aquatic scientists subscribe to the carbon-limitation 
theory, but moat will agree to a platttude like "dlfKmnt 
nutrients an limiting bi different situations.** Such unquali- 




^L.(.y I lyi lied material 



NUTRIENT CYCLING IN FRESHWATER ECOSYSTEMS 



101 



TABLE 2 An Example of Components of the Diurnal COj 
«id Budgrt for L«lis 2Z7. M* an tar • Diplli Of OB m. 

31 July-1 August 1972. All Values are in nmokitMttr, 
PrcMluction Figures are Ghran for CO2 Only 













1 


/a $itu dianiB/lir at night 








|>iB«ailoii+se«iki 




*iM 


-1.91 


2 


DafkbottblaaAil 










(■ reapisalioa/hr) 




♦I.S6 


-1.72 


3 


Invasion (+) or BvH 


iioa(-)/hr 








(' ® - ® ) 




♦ 1.48 


•0.19 


4 


Net observed thanj 


• indaylWit 


32 




5 


24 hr inva<iion 




36 




6 


Net productioa 










(- «> ♦ ® ) 




68 




7 


24 hr resplraliaii 




ii 


41 


8 


Cros'! production 
(=©+(£) 




lOS 





fied statements are totally meaningless when considering 
cnHM of eutiopliicalioii. It is necsMiry to specify whether 
nutrient limitations arc causes or results of phytoplankton 
blooms, and whether they operate live percent ol the tune or 
lifQr, on a daily asweU asan aninul icde. Lake 227 ofTan 
SOOie excellent illustrative material. 

There is no doubt that pho^horus and nitrogen were 
Rspomible for the eutrophicatioii of Lake 227, since addi- 
tion of these two elements causes an enormous increase id 
phyt(^lankton despite extremely low Die. Four years of ex- 
periments in large isolated columns (Sehindler, unpuU.) 
have showr that the increase in phytoplankton could ntit 
have happened without the phosphorus, but that it would 
have been smaller if no nitrogni bad been added. Carbon, 
in either inorganic (CO2 gas or bicarbonate) or organic 
(sucrose, glucose or acetate) form caused little or no increase 
in standing crop, whether added alone or along with phoa- 
phonuand nitrogen. 

Yet our data indicate that at midday in sununer photo- 



synthesis is definitely carbon limited, and phytoplankton 
win not respond to liffit, or to any nutrient except DiC 
(FigWfe2),even thoufii at d;iwn the lake exhibited a typi- 
eam^t<ontrolled response (Figure 4; Fee, unpubl. data), 
with csrbon-flxation of sewage-tagoon pfopottkwa (up to 
25 fM of C/1 X hour) The total daily productinn. even 
though it may take place in only 2 to 3 hours, is far higher 
than bi oligotrophic lakes of the area. As mentioned above, 
both respiration and atmospheric invasion :ire important 
in the diurnal repknishmenl of COa in tlw euphotic ^one. 

Scrutiny of the internal kinetics of the carbon cycle are 
also of interest. Just after dawn in midsummer, when gross 
production in excess of 20 tiM/l hour is observed, at a Die 
concentration of 50mM/I and a pH of 10, dissolved gaseous 
COj is 7.4 X IQ-^ iMI\. If all DIC is supplied to phyto- 
plankton via the gaseous COj pool, this pool must be re- 
plenished with a rate constant of 0.75/sec, i.e., its turnover 
time is 133 sec. This is the same magnitude as the slower 
rate constants for equilibrium reactions in DIC cycle, as 
found in pure solutions by chemical means. It is therefore 
unUkely that organic substances dow chemical reactions 
directly, although under such extreme conditions just colli- 
sion frequency and membrane efficiency may be important, 
sbice there are only 10^ COj molecules/cell in the eui^iotk 
zone. 

Demands by phytoplankton for gaseous CO2 in other 
I»odttcthre systems are lower than in Lake 227. For example, 

p]]\ tu>pl.u'.kri)n in ;!ie r xUfmely productive sewage lagoon 
described by ICing (1972) would require a rate constant for 
rei^enidunent of gaseous CO] of oidy 0.06/sec to meet 
their demands, if calculated in the same manner. If we a^ 
sume that phytoplankton utilize UCO)~ directly, i.e., it 
is not first di^ydrated to COj , the supply of Die in Lake 
227 is even lower in relation to other lakes. It is clear that 
in the tew natural waters where carbon is "limiting", to 
pliyiuplankton, it must be regarded as a symptom, rather 
than a cause, of eutrophication. 

It is obvious that complete access to the carbon, Ditrogan 



TABLE 3 A Summary of the Phosphorus Budgets for Lake 239 (Oligotrophic I and 
Lake 227 (Artificially Eutrophied by Addition of PO4 and NO3). All Data are in 
g/im>Xyr 





Phosphoras 








Carbon 






L. 239 


L.237 


L.239 


L. 227 


L. 239 


L227 


Pi ri ijTiMlioB 


0.05 


0.05 


0.67 


0.67 


5.31 


5.09 


Runoll 


0.10 


0.06 


1.03 


0.93 


38.9 


54.12 


Atmospheric gases 


0.00 


0.00 


•> 


f 


0.0 


22.60 


Total natural input 


0.15 


ail 


1.71 


IM 


44.1 


81.82 


Fertiliser 


0.00 


a48 


0.00 


6J0 


0.00 


0.00 


Total lapst 


0.15 


as9 


1.71 


7.90 


44.1 


81.82 


Outflow 


0.04 


008 


0.81 


1.C3 


28.6 


37>I5 


Retention 


0.11 


0.50 


0.90 


6.27 


IS.S 


MA 


% Reicntion of input 


73 


S5 


54 


79 


35 


S4 



Copyrighted material 



102 



0.1IIILteillNDLBII«al. 



FIGURE 4 ReiponM of Lak* 227 
ptiytaplanktnn takMi at diffMSut 
1 0f tfty to four dIffSiMt lif^t 



II VtfOM of OVC Ot tflO timet tOM|llM 

.vrrr rnkBn m»y t)« obMined from 
Figure 3. Alttiough phosphate <i»- 
mand by tht phytoplanfcton was 
unaormly hl«h all day <h - 0.24 to 
028 for lha PO4-P pool), and tha 
yliytoplinklon tton^kif crop 



IITOliI oMmphvi lA) WPN to 
fnMiuliOii of tfio Mm wWi ^o^ 

phata and nitnta, th*r« was no d« 
tactabla rfiort t»rm incrawn m cat 
bon fixation dua to phoaptiata 
addition*. In moming (DIC > 50 to 
60mM/I| OKlfMHlvMtfi photoayn- 
iMMiflll^C 
>of<iol l »t i oipow 



eurva was typical By midday 
IDIC ■ lOy M/l) pholCHvntheiij 
was er 1 r ernalv I L»v jrid c i3iiT i o^led 
by availabia carbon Iim Figur« 2). 
Similar lakat «whMi did not racaiva 



writh an atymptolo (maximum 
fynthatk ratal from S to 2& 
that of Laka 227, 
Fao, 1973. 



I.»oJ 

i 

m 

! ••I 

o 

b 

K 

U 




JU9L 



•.It 



and oxygen budget*, as bt Lake 7Tf, cannot be achieved In 

great lakes and ixeans. Yet estimates of gas exchange for 
these elements in such waters are important tu a number of 
critical enviTonmentai Issues besides eatropMcatlon. For 
example, the rate at which the culturally caused increase 
in atmospheric CO2 can be dispersed in the oceans has long- 
term ^obal implications for climatic change (Broecker et al., 
1971). 

WVito gas exchange in such enormous systems has been 
measured by using bomb-produced and natural (Craig, 
19S7; Broecker and Olson. 1960) and the naturally pro- 
duced radioactive gas Rn (Broecker, 1965; Broecker ei 
oL, 1967; Broecker and Peng, 1971), only recently has it 
been poofUe to oompaie the lesultinK nwdeb to enipM> 
cally measured chemical enhancement (Schindlcr et al., 
1972a; Emerson, 1974). A reasonably accurate picture of 
atmoqphere^witer exchange of cat bon and nitrogen hi 
fiesh waters should emerge during the next decade. 

RETURN OF PHOSPHORUS AND CARBON FROM 
SEDIMENTS 

Understanding of sedimentary "feedback" and its control 

must be a major goal for limnologists In the next decade. It 
has been invoked as an important factor in freshwater chemi- 



cal cydes since the dasslc work of Mortbner (1941-42). par- 
ticularly in the control of phosphorous feedback from sedi- 
ments by predpation with iron (Einaek, 19J6; Hutchinson. 
1957). Posrible chemical interactions at the mud^ter ^nte^ 

face have been modelled in great detail (Stumm and Leckie, 
1971). As late as the mid-1960's, the belief was widespread 
that sedimentary return would render attempts to rehabilitate 
culturally eutrophied lakes useless. The Idgh concentrations 
(if phiisphonis and ndier tintrients lust above sediments dur- 
mg late summer stagnation was regarded as evidence for 
'feedback.** More recently, the rapid recovery of Lake Wash- 
ington after diversion of sewapc (Fdmondson. 1970. l'^'^2) 
cast considerable doubt on the above belief. In mass-balance 
studies of Lake Mhmetonka. Mepid (1970) has riiown that 

althnu4;h return of phosphorus from sediments occurs, net 
retention of phosphorus by sediments is extremely high. 

In radtotiaoer txpethnenta wheie "C and were al* 
lowed to equilibrate with seston and to sediment in in situ 
water columns in Lake 227, no significant return of either 
radiophosphoras or radiocarbon from sediments has been 
detected for a period of one year, even under anaerobic 
conditions (Lean and Schindler, in prep.). In a second ex- 
periment, where a ferric hydroxide-phosphate coprecipi- 
tate containing both *' Fe and "P was sprayed over the 
sediment surface in the anaerobic hypoUmnion, there was 



Copyrighted material 



MuniiiNTeveitNO m nmnmnn teovnrwm 



103 



no significant retufn of either element. Mass-balance 
iliidiM of input, output nd changes of nutrient in the 
water column of the entire lake also indicate that sedi- 
menury return is insigniflcant (Schindkr and Lean, in 
pmi: SchimOer, unpubl.). 

Micrdbial rather (han chemical tnrces appear to regulate 
movement of phosphorus and carbon at the sediment-water 
Hiterfaoe in our iakies. Lean and Schlndler (in prep.) found 
high phosphate uptake hy 5<?ston in anoxic hypolimnetic 
waters of theii isolated column experiments in Like 227. 
Once in particulate form, the element wu again sedimented. 
Further studies by Schindler and Frost (unpubl.) have shown 
that (1) biological pioceaes for sedimentation of phot- 
phonn and CMbon an extremely efficient when oxidizing 
conditions aie pieaent at the mud-water interface, and (2) 
that sedimenlatian efficiency of phosphorus and carbon is 
much reduced in the absence of the sediment biota (Figure 
5). 

On the other hand, it is clear from the study of Burns 
and Ross (1972) that significant return of phosphorus from 
■dtneots does occur in Lalce Erie. The reason for fheie 
differences is obscure, but since the molvbdate-tesl was 
employed in the above woik, the amount ot true ortho- 
phMphate letnmed itunlaiowo. 



OVERVIEW 

It is not difficult to see why freshwater ecosystems appear 
OOmpliBX, and why relatiottstiips of biological dynamics 
to chemical phenomena appear to be obacoie. The tndl- 
ti(inal approach to freshwater chemistry has been a static 
one. where chemical concentrations serve purely as baclc- 
ground bifonnatlon-a sort of decorative tapestiy upon 
which limnologists have displayed the so<aIled "dynamic" 
processes, such as energy flow. These processes have been 
of intentt for the past tiiree decades. The smaU amowit 
of information which we have summarized here damCNt- 
stiates the sterility of such an approach. 

The flux rates of nutrient dements are extremely 
flexible, and it is possible that small nutrient pools turning 
over rapidly furnish the same supply of nutrient as lar^ e 
pools turning over slowly. The measurement of pool size, 
i.e., concentration alone, may therefore b« completely 
misleading when roles of nutrients are assessed. 

Modern techniques, such as radiochemistry, allow many 
important chemical mechanisms and rates to be examined 
without interfering with ecosystem function, in nuich the 
same manner that "*C is used in the study of primary pro- 
duction. Only by using such approaches can sfanifaurities 




■ mm . ExpariiTMnls war* <ton* in 
«Mo IH«f iMakart contatning 200 ml 
olMdiment and 500 ml of epilimnion 
W, kapt on ■ laboratory ihalf in 
. Moat of til* racUophoa- 
i ratfiom^Mi reiuaninn to 
'MB>10'liiiiMtawlar 
iMiifM. m dmrminad by Safihadax 
fnetionation. On day 55 ndlmanti 
nara mixi-d vviih -..^uiirr und allowad 
to laattla. Moi t ol tha radiophot- 
phonit and radiocarbon waa ratumad 
to Ndlmanti in Hm i 



MjivM ■ p»rea«ii of hoMpi 
■^4«Ml «• Me 




• sees 



Copyngliico na.u lal 



104 



O.W.fCMNOLEfl«al. 



or diflerenoes in ecosystem Function be accurately judged. 

It is believed th;il sune of the apparent overwhelming com- 
plexity of ecosystems will disappear when such functional 
rdatioiuhipe for major mjtrient dements have been 
analyzed. 

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Braecker, W. S. I96S. The application of aatunl radon to probleint 

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on Difniiioe In Occam and Fiedi Wataia. LamontGooL Obaenr., 

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Braecker. W. S.. and E. A. Olson. I960. Radiocarbon from nuclear 

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Broecker, W. S., and 1.11. Peng. 1 97 1 . Tlic verticil distribution of 

radon In the BOMI X .ircj. Karlh Planet. Sci. Utters. 11 99-108 
Braecker, W. Y. H. Li, and J. CromtweU. 1967. Radiuffl-226 and 

iidea-222: Concmltatlon in Adanlk and Hdlk Oceans. Sci- 

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Bums, N. M., and C Ron (cd.) 1972. Oxygen-nutrient lelauondiips 
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Edfflondson, W. T. 1970. Pliosplmriis, nitrogen and algae In Lake 
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Copy righted material 



NUTRIENT CYCLIf*G IN FRESHWATER ECOSV SI tMS 



105 



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Cc( , J od material 



PRODUCTIVITY AND 

MINERAL CYCLING 

IN TROPICAL FORESTS 



FRANK B. GOLLEY 



ABSTRACT 

limited information on tropical forest ecotyMcmt suggest that bio- 
mm of vdgetttion, pemni of the Miricnt iawitofy in tlw Womas*, 
and tapUHy of nutrient cyding is higiwr eompared to temperate 
foiest eyitems. Mean tropical forest net primary productivity is 
about 23 mt/ha/yr. Mean tropical grassland productivity is higher 
and savamnah is lower than tropical forest net produiiion TropK il 
forest appear to use about 70-80 percent ot the ^ross energy con- 
verted in photosynthesis in maintenance of the plant mass and, 
Iherefofe, fomt gfon pnnury production is neat 70 mt/ha/yi. 

The region of the earth termed "the tropics" includes por- 
tions of Asia, Africa, the Americas and Oceania. While the 
image conveyed to many persons resident in temperate le- 
giont is a hot, humid, lowland covered with tali forest, ac- 
lually, the tropics include a wider range uf ecological com- 
munities than any other portion of the earth. These tropical 
communities can be arranged in a matrix with altituile on 
one axis and quantity and duration of rainfall or evaporation 
on the other (Figure 1 ). Forest communities tall in the lower 
and mora humid pofdon* of this matrix, as distinct from 
savannahs, grasslands, deserts and high altitude vegetation. 
Forests, themselves, form a continuum ranging from the 
wet tropical rain feraat as found in Quibdo, Colombia, to 
the diy deciduous forest in the Gangetic Plain of India. 
Further, in most tropical areas disturbance of the land- 
aeape has resulted bi widcapread seoond'growth forcita of 
tUfTerent ages. Research on these various forests is uneven. 
In some we luve considerable detailed information on the 
structure and function of the ecdoiical qntem: in others 
we have merely lists uf qieciae and miloellineotti natural 
history observations. 

106 



Review of production and mineral cycUng of tropfcd 

forests ideally would establish the range of variation in 
these two functional parameters for each type of forest, 
the frequeflcy.distributlon of each parameter and the 
mean or median condition. Unfortunately the available 
data are inadequate to develop a review in thu depth. 
Neverthelett, the objecthw of thb paper will be to describe 
the range of production and inineial cycling in tropical 
forests, within the context of eco^stem stnM:ture and 
function, as far as existing information will dlow. The 
source of data in summary figures and tables has not been 
listed; the reader should go to the cited papers for 
references. 

OHAnACTERISnCS OF TROPICAL FORESTS 

An ecological ^stem has nun>erous stntcturai and func- 
tional characteristics, which, together, explain its behavior 
over space and time. Structure includes biomass, diversity, 
and chemical makeup; function includes energy flow, 
productivity, mineral cycling, phenology, resiliency to 
stress, and linkages with other systems. Because of the 
variety of types of tropical forests, and the taitemal com* 
plexity of any single forest, it seems best in an analysis 
of this type to adopt a strategy which will not only pro- 
vide a review of our knowledge of the Amction of troplcsl 
fnre<t<;. but also will consider function in the context of 
the ecosystem and the biospiiere. This strategy adopts a 
black hw approach, and focuses on the tropical forest as 
a unit of study, with linkages to other ecosystems through 
the environment (Figure 2). This unit can be analyzed into 



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CopyrigliiL.o na.u lal 



loe 



FRANK a GOLUV 



BIOSPHERE 

4 



Tropical Biooe 

TROPICAL 
FOREST 



ocaon 



FmietiMt] 

Groups 



( 


;ontfolle 


J 








prod. 


d*comp. 







Species 
Popnlstioiis 



10^+ SpMiM 



FIGURE 2 Div«ntl»a««in««w 




I to 4m OeCMM. HM f OfMt 

group* md into 

•f 




I wiety of subunits which interact togrthM to pioduce 
fhe IwliiwiiQf of the whole lyitam. 

In this view, tropical forerti m miidB up of a variety of 

chemical compounds, organiasd tattO functional groupings 
which include producers, decomposers, and controller con- 
sumers (Figure 2). These groups are composed, m turn, of 
qiecies populations, which an the fundanwntal unit wtddn 
the cominunity These groups are linked through the trans- 
fer of energy and materials, so that changes in one part are 
tiananitted thfou^HMit the vatem and steady state can be 
maintained. 

With this basic conceptual framework we can conceive 
of the trofrfci] foiest asan eedo^ed unit exposed to the 

environment and linked to other units through the environ 
ntent. Two aspects of the envixonment are of interest in the 
context of prodtictlon and mineral cycling. These ire the 
energy input to the system from the sun jiid tlie mineral 
input to the system from rain, dust and the substrate. 



Net radiation to the system is the difference between 
the downward flux from dlreet and diflRiae aunUiht nd 

thermal infrared radiation from atmosphere and clouds, 
and the outward flux from retlected sunlight and thermal, 
faifnied radiation from the ground. The net radiation gain 
is dissipated hy cvuporation of moisture, condensation of 
moisture or conduction and convection by wind. If soil * 
moisture is adequate, evapoiation b usually proportional 
to net radiation. Budyko's (P^^, 1*'S6) data mapped by 
Gates (1962) show that net radiation is higher near the 
equator and over the oceans. At the equator net radiation 
ranges from 60 to 140 kcal Vrn'/yr, according to Gates. 
This energy powers the movement of water through the 
ecosystem. Sbioe water is the solute for most essentU de- 
ments, the movement of water powered by net radiation 
energy is the basic process underlying mineral cycling. As 
ht as I know. Odum ( 1 970) is the only person who has 
studied this phenomenon on an ocoqratem baslB in tiopiesl 
forests. 

Vegetation captured through photosynthesis only a few 
percent of the acdar energy incident to the canopy. This 
photosynthetic energy is employed in the maintenance of 
the ecological system and, if the system is growing, in ttie 
construction of new tissues. Production or productivify in 
ecosystem terms is the new organic matter prown by a sys- 
tem, in a steady>sute system the amount of matter 
transferred or availahle to be transferred to die next fbne> 
tinnni trophic grouping. Net primary productivity is thus 
that material available for maintenance of the other non- 
plant parts of tte steady-state system. If the system Is not 
growing there is no net ciimiiuinity p:odu<.-tiun; if it is 
growing there may be net community production. There 
must always be net prtmary production, althougli it be> 
comes smaller in amount as the steady-state condition is 
established. Thus, the physical-chemical description of the 
tropica] forest ecosystem fequifesinlbrmation on the 
energy input for the work of maintaining the system and 
on the chemical kinetics of the elements which are essential 
in the construction of the IWing astern. These two funda* 
mental processes are included within the topics of produ^ 
tioo and mineral cycling. 

PRODUCTIVITY 

This review will concentrate on production ot vegetation 
tai ccoeystemawMdi we HMuroe are at or near steady^atate 

conditions Few data on true community production in the 
tropics are known, it is well understood by ecologists tint 
tfiei* are two Mnda of production of vegetation by Hie 
primary producers, as they arc often called. The total energy 
capture by the plants for the work of the ecosystem is the 
gross primary production. After some of this energy b ex- 
pended via respiration in the work of maintenance of the 
vegetation, the remainder is available for other populatioru 



Copyrigliiuo r:ia:.chal 



PRODUCTIVITY AND MINERAL CYCLING IN TROPICAL FORESTS 

in the system. This remaining energy is the net primary 
production. Since man is one of these "other populations** 

we are especially interested in net primary pr<)d\iction, and 

we tiave numerous measures of its magnitude. Cross primary 
productkm iileueadly meaiufed tnd the data ire fewer. 

Tropical forest productivity has been examined in a re- 
cent iiymposium sponsored by the International Society of 
IVopiical Ecdogy, INTECOL. and the bdiin Nationd Sdenoa 
Academy at New Delhi In February 1971 (P. M. Goliey and 
F. B. GoUey. 1972). Summarization of the available data on 
net primary production (Figure 3) suggests that the distribii* 
tUm of data is skewed toward lower productivities, and Ihe 
mean is about 23 t/ha/yr. Mean tropica] grassland net pro- 
duction is slightly higher and savannah iuwcr than lurcst 
plodnetfcMU Ueth'S map showing the distribution of net 
primary production over the earth (Figure 4), fflustratettbe 
heterogeneity of production in the tropics. 

It b not nuprfaing that the fiteqoeney diitifbution of 
net production is skewed. Production like any other process 
b limited by enviroiunental factors and we would expect 
flint tliere wiD be relatlvdy few eeologiea] dtuatlon with 

optimum producticin conditions The expected curve should 
be skewed to lower productivities with a long tail to the 
highest production levels. The envhotmental iacton ctm- 
trolling tropical production nedMcilbed and ilhiatnled In 
GoUey and Ueth (1972). 



- 








1 


, 1 , 


1 1* » li 40 ■• 



i; 



]_[ 



Savannah 



0 10 » 30 

N€T PRODUCTION (»/h4/»»l 



FIGURES Fraquancy dictrikuiian of priimry Mt production of 
tropical communltiM In iiwMa torn per hOBlan INT year, alMr 
titiaa). 



109 

Cross primary production are too few for graphical pre- 
sentation. At this stage of iiwestigatfon, abowt all we can do 

is correct the net pnidiK (ion data by calculating the amount 
of energy utilized in nuintenance of the plant mass. Tropical 
forests appear to use 70 to 80 percent of the gross energy 
intake in maintenance, leaving 20 to 30 percent for net 
production. The frequency distribution of maintenance as 
• |Wfe«nt of gross production for all vegetation (Figure 5) 
ilOWl two peaks. One peak represents grassland, herbaceous 
vegetation and growing plantations of trees; the other peak 
represents mature tropical and temperate forests. With this 
correction we can calculate that the average grots primary 
production of tropical forests is about 67 t/ha/yr or 28 X 
10^ kcal/m^/yr (GoUey, 1972a). It is not appropriate to 
put a range on this mean value, since the peroentagB of 
gross primary production used in maintenance may «uy 
depending upon growth conditioiu. 

Jordan (1971) also hu examined trapleal prtaiaiy pro- 
ductivity from the point of view of the efficiency of pro- 
duction. Efficiency was defmed as the sum of energy stored 
in wood, in leaves, fndt and litter over the total solar 
energy available to the community. Jordan found that thiO 
rau of wood production in intermediate-age stands on 
mesic sites is similar in tropkal and temperate lefloos; 

however, the rate of leaf .ind litter production is higher in 
th^ tropics (Table 1). In contrast, efficiency of wood pro- 
duction Is hitfier at highw latitudes. Jordan hypothesizes 

that where solar energy is abundant, as in the tropics, there 

has not been selective pressure toward maximization of 
wood production. 

The data on primary production give an estimate of the 
energy available for vraifc within the tropical forest qrstem. 
Odum (1970) also has c^culated the other ecosystem energy 

flows for a montane fonst in Puerto Rico. Incoming insuli- 
tion in that forest is 3830 kcal/m^ /day and gross photo^n- 
thesis is 131 kcal/m^/day. Evaporation and transpiration 
amount to 2975 kcal/m^ /day, which contribute to drbdng 
a mineral flow of 0.24') >;rams/rri^ /day from wood to 
leaves. We would expect a similar range ot tluxes in other 
tropical forests, depending to a large extent on the aMiS' 
tute levels tvailaMe bi ^ aoQ and the evuvotfanspbtUon 
ntet. 

MINERAL CYCUNQ 

There ate about 90 chemical elements that m%^t occur 

naturally in the environment, hut not al! of these are es- 
sential for life or occur commotUy in living tissues. The most 
abundant elements fan the Mospheie are oxygen, carbon 
and hydrogen, which occur in amounts greater than 10* 
kg/ha (Oeevey, 1970). These elements plus boron, nitrogen, 
fluorine, sodium, magnesium, silicon, phosphorus, sulfur, 
chlorirte, potassium, calcium, vanadium, chromium, manga- 
nese, iron, cobalt, copper, zinc, selenium, molybdenum. 



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CopyrigliiL.o na.u lal 



NioouGTivrrv and mncii al cvcimo m tromgal FORKit 



111 



14^ 



z 

M 
a. 
O 
c 

lU 

s 
S 

i 



20 40 60 80 

R AS A PERCENT OF GROSS P 



100 



FIGURE S Th« t t rnt/ ums j of stand* of v*9«tat>on with niiotrofriiic 

I IRI a • POTMHt of imi primary production (growPI. 

I In «M fifMi* itmn <Mkv. 



tin lod iodine are eiwndil for Ufe. Nitrogen, cakium, potaa- 

sium, silicon, magnesium and sulfur occur in quantities of 
toon than 100 kg/ha in the biosphere; the leciMining 
dementa usually occur fai trace amounts. These dements 
are accumulated in the living tissue of the community and 
are cycled between the varioui tpedts populations and eco- 
sjnttm components. The movement of elements wtthfai the 
biologica] part of the ecosystem can be called the biological 
QTcle of elements (Duvigpeaud and Denaeyer-de Smet, 
1970). 

The chemical elements in the biological components are 
derived from the substrate and the atmoapbeie. The gedo^ 



cd piooeas of erodon and deposition move mineral elements 

through the Uthosphere and hydrosphere. In terrestrial up- 
lands, elements may enter the system through rain or dust 
and from weathering of soil minerals and are lust to ground 
water and streams, comprising a geological cycle of dements. 
The biological cycle forms a shunt on this long term geo- 
logical process and is characterized by its intensity and 
rapidity. 

The geological cycle is mainly under the influence of 
water movement and availability, temperature, and to* 
pography as well as the parent rock materid. Hi^ year* 

around temperatures and abundant water found in certain 
tropical forest areas result in a relatively rapid geological 
cycle. It hu frequently been suggested in the literature 

that this t;cological process is so accelerated in tropical forest 
environments that the biological cycle has of necessity taken 
a spedd form in order to conserve the esaentid dements 
for life. Specifically, i! been suggested that nutrients 
are stored in the biological part of the system where they 
can be protected from erodve forces, and that the time the 
elements arc in the substrate where they can be leached 
from the system is minimized by a variety of ^ecid biotic 
adaptations. In flib part of the review we wffl briefly con- 
sider the inventory of nutrients in tropical forests, the in- 
tensity of the biological and geologkal cycles, and evaluate 
the adaptations to preserve nutrients against the geological 
flux. Only certain macroelements wffl be discussed here due 
to limitations of time and space. 

Mineral cycling in a tropical forest can be considered in 
tenns of a simple diagram which is merdy an expandon of 
our earlier mode! ( Figure 6). The amount of nutrient in each 
compartment is determined from its biomass and the c«hi- 
oentiation of nutdent in that biomass. A hrge biomass is 
generally characteristic of tropica! forests (Tjble 2). The 
quantities of wood, especially, are large in iropual forests 
»id swetage about 300 t/ha, compared with about 1 SO t/ha 

for temperate forests. Tlicrc also is evidence that the con- 
centration of chonKal elements differs from tropical to 
temperate forests (Figure 7). Rodin and Badlevieh's (1967) 

excellent suminar>' of data suggests that tropical forests con- 
tain in their biomass larger percentages of silicon, magnesium, 
sulfur and trace dements and smaller quantities of potas- 
sium than do temperate forests. The effect of these different 
quantitiaa of biomass far surpasses the efliect of differences 



TABLE 1 Comparison of Rata and EffldMcyofProduelionhiOlffBfBnt 

Vegetation (After Jordan, 1971) 



Forest Type 



Rata of Production (s/m'/yt) 
Wood Leaves 



Effkkncy of 
produciion/tolal sohir eMigy) 



Wood 



Leaves 



Tropical foiests 350-900 180-2,300 0.28-O.SO 0 15-1 15 

Temperate fofWtt 410-2.407 270-500 0.42-1.81 0.21-0.44 



Copyrigliiuo r:ia:.L.i lal 



112 



FRANK B. OOtLtV 



»64 




A 6^ 



Herbivorei 








A 8,9 


CarntvoTM 


C9 





Roots 



FIOURE* Oli|fHia«niiMnrieydin|ina 
Hm f f Um m >omii < iiIii an I nd l ind fcy <w do w l It 

c— ipp w ia m idantifiMi at iioxat, outiid* MNircM m ■morphoui 
flgMiM. Hi* tranatar functtan* ••« itMlicalad bmtwmn eompofMnti 



in concentratioa, wHh die mult Ilut tropical forests usually 
have larger inventories of nutrisoti in didr bkMnan than do 
other types of forests. 

These between bkmie comparisons should not conceal 

the great variation in chemical concentration within the 
tropical forest. Comparing the averages of Rodin and 
Bazilevich (1967) with data from forests in Panama (GoUey 
etid^ia press). Puerto Rico (Jordan et al., 1972) and the 
Amazon (Stark, 1*'71 , Table 3 gives an indication of the 
extent of tiiis variability. These few data show the low 
nutrient status of the Amazon forest on podiolk sands, 
which has been so well described by Stark, aS Compared tO 
the hi^er levels in Panamanian forests. 

If we compara the Standing crop of akmaats in the 
biological part of the tmpica! forest ec<isystem with that in 
the active part of the soil, we can judge the role of the vegeta- 



tion in sequestering nutrients. In five forests in Panama 
(GoUey etal., in press) only phosphorus and potassium are 
held consistently in large percentages in the vegetation (Table 
4). Apparently it is advantageous to the system to con- 
centrate phosphorus and potasshim in vegetation because 
of their mobility, small inventory or both. In the nutiicnt- 
pooi An)u/.on podsol sands, ^tark (1971) has presented data 
suggesting that a larger number of elements are stored in 
the vegetation than in the Panamanian tropical forests. 

totalled infoimation on one important part of the bi- 
ological cyde, litter fall, is available for a number of tropical 

forests and serves as a rough index to the rapidity of the 
cycle. Rather than reproduce these descriptive data, it will 
be man useftd to consider them bi terms of the niventory 
of nutrients available in the vegetation mass. The ratio of 
element inventory in biomass to annual Utterfall is a measure 
of turnover time. For the maerodcments phosphorus. pota»' 
sium. calcium and magnesium, turnover time is dimensioned 
in years and is almost always less than 100 years (Table S) 
and nwiages about 20 years. Clearly, the biological cycle is 
quite rapid for these chemicals. 

There are many fewer data on the relation of the biological 
cyde to the geological cycle in tropical forests. One example 
from the Tropical Moist forest of Panama will provide some 
insight into the process. The flux from these ecosystems is 
represented by discharge to streams; input is by rainfall; 
the difference between input and output is weathering of 
soil minerals which recharpes the soil inventory. Phosphorus 
and potassium appear tu be in balance in the system (Table 
6). The input from rain equals output to streams, and ap- 
parently the recharge from weathering is relatively small 
Calcium and magnesium recharge, in contrast, must be large 
to balance input and output of the system. The amittal up- 
takc of phosphorus, potassium and calcium by the vegetation 
exceeds the disciiarge, while for magnesium the reverse is 
true. These comparisons, together with those on inventoiy 

of nutrientf; (Table 4). jiup^est thai the supply of potassium 
and phosphorus is relatively poor and mineral cycling adapta- 
tions have developed to conserve Ihese elements. These 
adaptations include storage in biomass and rapid intemal 
cycling rates. The rate of calcium cycling is rapid, yet this 
dement is abundant in the sofl and is not stored at high 
concentrations in the biomass. For the other elements, the 
environment appears to provide nearly adequate supplies 
for system maintenance. 

Jordan era/. (1972) have found a similar pattern in the 
Montane forest in Puerto Rico, but Stark (1971) in the 
Amazon shows a much wider spread of possible nutrient dif- 
fidencies. She has postualted a direct nutrient cycling mech- 
anism in the forests growing on podsols in which there is a 
mycorrhizal connection between dead organic matter and 
roots allowing tfie direct transfer of nutrients between them. 
The inevitable small leakage will eventually result in such 
poor nutrient conditions that the forest vegetation cannot 



Copyrighted material 



mOOUCTIVlTV AND MWtllAL CYCLINQ IN TROTtCAL KMem 

TABLE 2 BtomMirf PofMtOiMtmiMiilfw(inMrto«Diiidivwt/lw) 



113 



rofMt 


Canopy 


SMni 


VIMMIKH 


t Rools 


LnMr 


Thiftcal foiests 












Thittuid, nin fomt 


8^ 


360 


2.4 


33 


3.5 


llMiHid. mORHMM fbiwt 


3J 


Ml 


10 


25 


- 


11ulmd» tfiy evetgieen foiMt 


5j6 


229 




- 


- 


Puerto Rico, mangrove 


5.4 


40 


- 


5 


— 


Ghanii, inci'-l tropici) forest 




187 


- 


25 


13 


Congo, scconUitiy forest 


6.5 


116 


- 


31 


S.C 


Puerto Rico, lower montane foffMt 


8.1 


269 


- 


71 


19J 


BnzO, mottBtain wtiyan fomt 


9.1 


131 


- 


33 


- 


Ptann, tnpleri mailt diy 


73 


252 


3.9 


13 


6.2 




lU 


35S 


1.7 


10 


2.9 


PluunMf pmnonttnc wt 


IdLS 


258 


0.8 


13 


4.8 


hnama, riverine 


1U 


1,163 


I.I 


12 


14.1 


Panama, matigrove 


3.5 


159 


0.1 


190 


102.1 


Temperate roieilt 












Ptoe fofMt 


6.4 


122 


4.0 


29 


37.5 


ConifinMis fomt 


104 


114 


zo 


38 


36.6 


Dedduotttfomt 


16 


142 


3jD 


37 


lOJ 



z 

UJ 

> 

a: 
O 



o 
yi 




FIGURE? Comparitonof 
(whits bar) foratta. Oau from Rodin 



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114 



FIMIIKI.OOLUV 



TABLE 3 CompMiwn of Element ConceirtratiOM In 
Tropical Forect Vaflmtion (% dry wtight) 





N 


P 


K 


Ca 


Mg 




lAQ 


0.14 


i.29 


1.42 


0.25 


AwrtoRIco 


0.70 


0.J7 


0.51 


0.S8 


0.17 




1.40 


0.13 


0.31 


0.16 


0.16 


OwMll' 


1.22 


0.10 


0.82 


1.14 


0.28 



*NoMrllluaetic meM. 



TABLE 4 Percent of Total Element Inventory in the 
Vegetation in Panamanian Trop*c«l Forests Represented 
by SptcNIe Nutrimit Eiiowiili 



Potest 


P 


K 


Ca 


Mg 


Na 


Tropical moiit 


89 


89 


12 


16 


16 


PnaonUoe «e( 


96 


8S 


4S 


22 


47 


Riverine 


99 


97 


61 


3S 


14 


Mangrove 


75 


97 


32 


89 


75 


TiopKjl moist 


82 


58 


17 


5 


2 


second grawtk 












(6 yi) 












Avera{;e 


88 


85 


34 


33 


31 



TABLE 5 Turnover Time in Yearj of the Mineral 
in VagrtMion by Litter Fall in Tropical Forests 





Elements 










P 


K 


Ca 


M< 


Tropical moist (Panama) 


25 


37 


22 


25 


Premontanc wet (Panama) 


9 


28 


17 


10 


High forest (Ghana) 


12 


10 


9 


6 


Deddttoos eveigfeen 


S 


6 


9 


8 


(lliailaBd) 










Moatne (Puerto Rico) 




14 


9 


10 


Bamboo dhuma) 


8 


3 


12 


9 


Dry deciduous (Thtfland) 


5 


7 


12 


5 


Div tli-i i-liious (India) 


38 




16 




Dr)' acacij (Senegal) 


27 


57 


27 


9 


Riverine (Panama) 


94 


93 


79 


'■ 5 


Man|ia*e (Panama) 


23 


8 


24 


5 


TABLES ConvMlMmof 


Biel«#e 






riCydtt 


in 1 TIrapinI Moht Forait 










Geological Cycle 




Biological Cycle 


Input Rain 


Stream Output 


Annual Uptake 


Btancnl (k«/ha/yr) 


(k»/ha/yr) 


(kl/ba/yr) 


P 1.0 


0.7 




11 




K 9.3 


9.5 




187 




Cb 29 


163 




270 




Ml S 


44 




30 





be maintained, in which case renewed erosion will permit 
new nutrient sources to be developed. This very interestiBg 
hypothesis should be tested by study of the mineral dy- 
naoiician Iheie podsol loai. 

CONCLUSIONS 

While the data on tropical fore?! produciion and mineral 
cycling are very limited, we have sutlicient intormation to 
devdop hypotheses for the deiign of the next stage of our 
work. We speculate thj( as one moves from cold temperate 
to moist tropical fuiest conditions, the biomass of vegeta- 
tion, the percent of the nutrient inventory in the bkmais 
and the rapidity of the biological portion of the mineral 
cycles will increase. These patterns have not one single 
eiuse, rather they are an exprenion of the change in envlron- 
ment providing improved growth conditions in the tropics 
but also more rapid chemical kinetics. The result is that in 
certain locations (podnk In the Amazon) and for certabi 
essential elements (P and K in Panama) the nutrients may 
become limited due to the intensity of the geological por- 
tion of the mineral cycling process. These situations may 
result in fragile types of ecosystems, even though they con- 
sist of a large mass with high diversity. Disturbance of these 
systems could require a very long time for recovery , s;nce 
die rapidity of the chemical kinetics would woik 8gHiiit 
establisliment of stability. If this is true, then, recovery 
would be very expensive in terms of lime and money. For 
this reason alone, it is worthwhile to increase support of 
tropical forest stiidies, which shmild be directed toward 
establishing the tragility ol the system, the steps required 
for recovery of disturbed systems and the role of the tropi- 
cal forest system in influendog the geological and hydiokigi^ 
cal cycles. 



REFERENCES 

Budyko, M. T. 1955. Atlas of the heal tjalance. Leningrad. (From 
Gates, 1962). 

Budyko, H. 1. 1956. Hw heat bilancc of the earth'* nirface. Traat> 
htion P» 131692. UJ. Dapt CMMMiee, Office Ttch. Servieei, 
WadilngtMi, DjC 

Decvy. E. S.. Jr. 1970. Mlnent cyde*. SeL Am. 223:148-1 S& 

Duvipicaud, P.. and S. Liinjtvcr De Smet. 1970. Biological cyclinf 

u( mmeralt in temp^ijie deciduoui forest, p. 199-225. in D. E. 

Reichle (cd.) Anjiysis of tcmpetate Ibiast eciMyiWti jp ii iiiat 

Verlas, N«» York. 304 p. 
Gatei, D. If. 1962. Eaeigy eMhanit in dw btaplMte. Harper and 

Row. New Yotk. ISl p, 
CMIey. P. B. 19728. Smmaiy. p. 407-413. /« P. M. Goley and 

P. B. Gollcy (compUers). Tropical ecology, with in BWiphiah 

on organic production. Atheni, Georgia. 418 p. 
Cillcy. I . b 14 ':b 1 iKrgy (lux in cc^sv Nicmv p 69-90 /-i J. S. 

Wieoi (cd.) l-cosy^tem ttructure and function. Oregon Slate 

Univ. Press, Corvallis. 1 76 p. 
Galley, F. B., and H. Lietb. 1972. Bases of oiguijc productioa in 

the Irapfes. Pi 1-M. /• P. M. Goley airf F. B. Coney (CQOipan*). 



Copyrigliico r:ia:.chal 



niODUCTtVITY AND MINERAL CVCUNO IN TROnCAL KMUtTI 



116 



TNpieal ecology, with an oiiflurit on ovate PiwImIIml 
A1hcll•,G•Ol|te.41B^ 

Gglhr. P. B.. I. T. McGiimls. R. G. OeniMlB. G. t ChOd ud 

M. J Ducvcr (In prc^s) Mineral cycling in a tropical moist 
fofeit tLOsyslcni Univ. of Georgia Press. Athens, Georgia. 
GoOey, P. M.. and i B. CoUey (compilers). 1972. Trupicjl ectlngf, 
with an cmphaui on organic pioduction. Athens, Cicorgia. 
418 p. 

HoUridsB, L. R. 1967. UfexoMOcalagy. IrapicilSdeiiGeCBntw. 
Stn Jote. Ooita Ma. 

Jordan. C F. 1 971 Producrivity of a tropical forest and its relation 
to a world pjllcrn of tnergy storage. J. Ecol. 59: 127-142. 

Jordan. C. F.. J. R, Kline, .md I). .S Sasscer. 1972. Relative sUbilitjr 
of mlnenl cyde* in fomt ecosyttemi. Am. Nat 106:23 7-2S3. 



Lieth, H. 1964. Vemich einen kartopaphischcn Darstellung der 
ItodBkltoHit dw FOuiwJocfcB mf dor Ende. p. JJrW. In 
GeoenphiKlietTueiimbiich I964-6S. M. Stehiw. WMjoden. 

Odtini. H. T 1970. Rain forest structure and mineral cycling hy- 
pothesis, p. H3-52. In H. T. Odum and R. F. Pigeon (cd.) A 
Tropical Rain Forest. A study of irradiation and ecology at 
El Verde, Puerto Rico. Div. of Tech. Info., U.S. Atomic Energy 
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Rodin, L. and N. L BuilBVicii. 1967. Prodwtioa Ud miMiri 
cyding in NiimuU >tp>lilloiii OUvor ind Boyd, EdtatMniilk 
288 p. 

Siarl^ N. 1971. Nutrient cycUqg. II. Nutrient d^tiibution in 



Copyrighted material 



ANALYSIS OF CARBON 
FLOW AND PRODUCTIVITY 
IN A TEMPERATE 
DECIDUOUS FOREST 
ECOSYSTEM* 



W. F. HARRIS, P. SOLLINS. N. T. EDWARDS, 
B. 6. DINGER, and H. H. SHUGART 



ABSTRACT 

Cubaa ncUibaHsm of a imiic Uriodendnm ttdlpiftta forect it 
tummarizAd biMd on twent etlimates of pools of carbon in 

ctosyslfm i.oniponent5 and annual flux« of carbon within the 
system, hsiimjtes of metabohc parameteri of the lulal ecosystem 
are derived from component processes (e.p.. ph mIi ■ ym 'A-sis, auto- 
tfOphic retpiialion, heterotrophic respiration). Kesidcnce time of 
caiboo in the foiett ecosystem is comparatively short (10 years) 
beeaute of dw iai|e carbon afOux in rei|iintion,«««n UuMigh some 
compooonti such as woody blomais and aofl organic nnttar haw 
residence limes of tOO to 150 years. Experimental constraints on 
interpretatiim of the current summary of ecosystem carbon metabo- 
\\\r.: .-.u: JiiLuv^fd with cmphjMs on improved measurement tech- 
nology and the need fur similar analyses ol ecosystem metabolism 
for diverse ecosystem types in order to adequately atieai the nia of 
die btosphare in ragulatinf global carbon balance. 

INTRODUCTION 

The International Biological Program has entered Ftiase III, 
tovoiiving qrafhMis ind exehangB of data pthered during the 
program. Synthesis involves drawing together all the available 
inlormation in order to answer or clarify specific questions 
and (o deterailne tckntiflc gmeraltties underlying the fonc- 
tional organisation and interactions among organisms, popu- 
lations and ecosystems. The variety and amount of informa- 
tion available for wdi ^thesis ii awesome. Theiefow^ to 
lealise die poimtlal contifbulion of Hm IBP to its primaiy 

* Research supported by the Eastern Deddnous Forest Bioroe, US- 
IBP (Contrtbntian No. 54) findcd by tha National Sciaaoe Founda- 
tion undar IntttaBaney AgfaamoM AG-199, 40-19349 wiiii Hie 
Oak Ridge Natioital Laboratory, which ii operated by Union 
Carbide Corporation for the U.S. Atomic Energy Commission. 

116 



objective, incrcasci! urdcr^tandine of productivity in natlUCt 
Phase lU has three tasks: 1 ) to summarize our understanding 
of trophic level components of various ecosystems, 2) to 
complete syntheses which emphasize coupling of trophic 
levels to evaluate both the total ecosystem behavior and the 
influence of particular ecosystem proceoes on the response 
of the total system and 3) to define areas requiring further 
research. This last task helps set the stage for the logical 
development of ecosystem studies to follow. 

Ecosystem Analysis In order to integrate the results of 
large, multidisciplinary researdt hito a holistie eco^tiem 
framework, a formal basis of analysis is needed (Reiciile 
and Auerbach, 1972). Considering the ecosystem as afonc- 
tional unit composed of a trophic hiersrdiy dispersed in time 
and space provides such a framework. Trophio4eval analysis 
of ecosystems relates flows of materials between components 
to overall metabolism of the system, in turn, fluxes of matter 
to and from the ccoqrstcm couple it to adjacent systems. 

providing some insight into the function of larger landscape 
units. Conceptualization of how the ecosystem fuiKtions 
forms tfie bvis for intensive observation, measurement and 
manipulation of system parameters. This body of data in 
turn supports expression of ecosystem behavior as sets of 
mathematical ftinctions. Together these operations of eco- 
system analysis are a powerful technique with which to ex- 
amine ecosystem properties, derive inferences about eco- 
system functioa, botli natural and following pertorbntion, 
and define asaaa of additional research. 

CSrhm Qwife As an example of ecosystem analysis and its 



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<Mi»LVlltOPCWI10iyWjOW«IPWIOIHICTWtTVIWAT l lll» tM ^ 



117 



potential for contribution to IBP synthesis, this paper sum- 
marizes progress on analysis of the carbon cycle of a tem- 
perate deciduous forest (Reichle etai, 1973a). Additional 
data have been obtained, particularly on below-ground car- 
bon dynamics and autotrophic metaboliim, which provide 
a clearer, but certainly not final, i M e incn t of carbon 
dynamics in this ecosystem. 

A thorau^ undeistandiiig of carbon dyiumJet In ttw bio- 
sphere is necessitated by the role of carbon in the chemistry 
of living systems, the coupling ol biological systems by car- 
bon thrauifi a conunon atnoipheric pool rad the interaction 
of biosphere and atmosphere to regulate ^obal carhnn 
balance. Man's activities (largely combustion of fossil fuel) 
are reaulting in an increase in atmoepheric carbon dioxide 
content of 0.2'^- per year (^"7 ppm by volume). Die observed 
increase in atmospheric carbon dioxide content represents 
roughly ono-hdf the carbon dioxide emitted In fonil fuel 
combustion (Anonymous, 1970). Uptake and storage in the 
biosphere and oceans account for the remainder. Recent 
discusatons (Olson, 1970; Whittaker and Likens, 1973) con^ 
elude that the role of terrestrial ecosystems, especially 
forests, previoiisly has been underestimated in assesiment 
of globd productivity and carbon dynamics. Evidence is 
accumulating that the total impact of man's activities has 
reduced biological production significantly and therefore 
altered the capacity of tlie global teriesttial ecosystem to 
regulate atmospheric carbon Mianoe (Olion, pp 33-43). 
However, it has been difficult to assess recent trends of 
global carbon exchange, much less extrapolate future trends, 
because of a lack of meanuements of carbon itonge and 
flow in different types of terrestrial ecosystems (Olson, 
1970). Questions of how terrestrial ecosystem processes in- 



fluence cartran turnover, its residence time in the bicH^hAra 
and, ia turn, atmoapheiic carbon balance wgently need our 
attention. 

METHODS AND RESULTS 

Anmial Budget €f CartMHi 

Site Description Tlu- study site is a second-p'owtb, meso* 
phytic deciduous forest on karst topography withm the US. 
AEC Reaemtion at Oilk Ridge. Tenneane. The fomt it 
established on a deep, alluvial, silt loam soil (Emory series). 
Mean annual temperature is 13.3 C, annual precipitation 
averages 126.5 cm and total riiort^wtve radiation averages 
\23.^ kcal cm"' yr"' fSnllins et al., 1973). The forest is 
dominated by yellow poplar (Liriodendron tuUpifera) in- 
terspersed with various oaks (Queraa yehit^. Q. alba, and Q. 
rubra principally). Understory species include redbud {Cerds 
cmadauis), flowering dogwood (Comus florida) and oc- 
casional btackgum {Nyssa sylvatica). Virginia creeper {Par- 
thenocbtus quinque folia), woody hydrangea (Hydrangea 
arborescens) and Christmas fern (Polystichum acrostichoiiies) 
account for approximately 90% of the ground cover bio> 
mass, although many other ^edes are present (Tayhir, 1974). 

Conceptual Model A conceptualization of the forest as a 
series of oompartmenls repressnting strueiuftl ooinpoaents 
in a functional notation is shown in Fi(UM l.lMlcOlll* 
partmentalizatioD sened as the basis for cdcuhtton of a 
budget which describes amounts of oiganic mattet 1) in each 
comparfmcnt and 2) transferred annually along each pathway. 
An annual budget synthesis is useful for preliminary descrip- 



ItS-INM 



FIGURE 1 Oiagnni of eonoiptuai 
modal of organic m«tt»r/carbon 
■torage and flow in a tamparata 
foreit ecosYftam. Pt " nat pttoto- 
■ynUiaais^ * aiitulfvplife vHipi* 
laStoiv Wn ■ hilwIiiBplile fplm- 
Hmu L - lo«» 4m to UMwM er 
^ooc tftou^ilna* LItlw Mid soU d^ 

compcMan include both microbiai 
and invartabrata arg«n»nit. Standing 
d— Chaood is ioelucM in tha branch- 




CROM MMMRr pmoucnoN nm 



NCI MHMMV PMOUCTRW lO^ -R.) 

m lYMt 

METCMIMMt MSMMTIQN 



CANOPY «l»'MROPt»S 




SOa. (MMNK 
MATTEM 


.JO 




''S4> 



Gopynghled maiei ial 



118 



W.P.IMIIIIIt«l«l. 



tbms of tfie tystan bdiavior. Theie Ixidiiett «Im lepretent 

initinl steps in the construction of iyumic unuUtion 
models (Reichle et aJ., 1973). 

Forest Carbon Budget Determinattnn nf a forest carbon 
budget requires use of a broad spectrum of data from physi- 
ologleal mdywi to structural and population parameters 
(Rcichlc i'f a/., 1973a). Iinlcpcndcntly derived estimiites of 
transfers using rates determined by diverse methodologies 
(e.g., huvest/aOoawtric analyies vi. gaaometrie uialyib to 
estimate production parameters) serve to focus attention on 
pioblemt of methodology as well as to verify estunatea. The 
time leioliition appropriate for paitlcalar interpretetiooi 
helpedelenitine which data eetl ice emphasized. Short- 
term environmental influences on physiological processes 
are not addressed when interpreting data on an annual basis, 
but information about total qntem dynamics can be ob- 
tained which is not readily appmnt when viewed at inofe 
detailed levels of resolution. 

The carbon budgat for the yellow poplar foiast it um- 
flMliEed in h igure 2. Carbon determinations were based on 
flame photometric detection following high temperature 
pyrolysit and catalytle liydioganation (Hortoa m cf., 1971). 
Estimatea of autotroph aboveground and ceo ttal root carboo 



pools (8j03 kg C m'' ) rates of annual, abowground aocumu- 
latkm (0.166 kgC m"' yr"' ) were based on allometrk ro- 
tations of weight of tree components and diameter breait 
hei^t(Sollitttand Andenon. 197 1; Harris efal. 1973). 

periodic inventory of tree diameters (Sollins fff a/., 1973) 
and excavation of stump and lateral root bionuss (Harris et 
al., in pieis). 

Underground autotroph carbon pool and associated phyfiF 
oiogical processes are the least accurately measured and 
least understood forest ecosystem components. Mean stand- 
ing pool of lateral root carbon (0.76 kg C m"' ) was deter- 
mined from a series of soil core data collected through the 
year. Net compartment uicrement was detsradned from net 
seasonal differences in lateral root bioraais pools to ht ^-8% 
for stands with S.0 to 10.0 kg C m'^ . Tumover of bteral 
roots was estimated from the summation of net decreases 
in standing pools determined monthly duiiag 1971-72. 
Significant death of roots <0.5 cm diam occurred in late 
q>ring and late autumn, while root production occurred in 
late whiter and midaummer (Hanls et hi piett)i Eariy 
spririB increases in biomass of roots <0 5 cm were accom- 
panied by apparent decreases in biomass of roots >0.S cm, 
suggBithig growth of the smallar roots at the expaoae of 
stored carbohydrates. Radiotracer experioMots using late- 



OmSL-OWO 74-1454 



CANOPY 
PREMTOIIS 



FIGURE 2 Annual carbon cycla in a 
Mmparata daeiduoui farMt. Ma^ 
AlMMtnaMl 




llnOwi 

of eftch box; net annual ir^cr^Ti.f^nt Is 
Aown in ttx lowar, right corner. 
Unit* of maaHir* ara 9 C m~' yr~ 
and gC m'^. A HMMiiarv of ««e- 
1 1 m Mhe H wii (s H n I j aadwii 



afv 4town fo fh9 H^if of tfia fla^i'a. 

Valuer! of PJPP and NEP in p«r»nlh««« 
ars bmmi on h»r»««t/»Mom»tric m«th- 
Odt; other yaluet are ba5«d on gaao- 

matric aiMlytM (raviaad aftar Rtichia 

mek, Itnal. 



CANOPY 
HERBIVORES 



7 \ 



OVERSTORY 

CANOPY 



UNOERSTORY 
CANOPY 



BRANCH - BOLE 
STUMP 



LITTER AND 
LITTER 
DECOMPOSERS 



HERBACEOUS 
STRATA 



LATERAL ROOTS 



■Ra 



Rh 



SOI L ORGA-VIC 
MATTER AND 
DECOMPOSERS 



Copyriyliicu liiaiorial 



MMtVM OF CARBON Pim AND HKNNICTIVITV IN A TCMPf RATE OMIOUOM PORItT ICOmnM 



119 



ftD inoculation of tract wifli ' ^Cowerote raveded i iharp 

elevation in '*C activity in small roots Lorrcspunding to the 
eariy«ipring period of active growth (Shugart and Harris, un- 
puMUied data). Root turnover thiou^ death largely occun 
from roots <0.5 cm diam. However, cyclic renewal of large 
support roots >2.S cm diam has been obierved by Kolesnikov 
( 1968) in orchards. Large dead roots attadied to living trees 
also have been observed in our soil munolith analysis of oak- 
hickory, pine and mesic hardwood forest ecosystems (Harria 
e/ al., in press). The rate of cyclic renewal of large roots is 
unlcnown. On an annual baalt, we luve assumed turnover of 
bfya roots to he very much slower than that of small roots. 
Other data on decay rates of various sized roots tend to cor- 
roborate diis assumption (Harris, unpublished data). 

Mean annual sundme crop ot O, and Oj litter layers was 
237 gC m'^ based on monthly collections. Soil organic 
matter dccieased Atom 4.fl%C9b dry weight of aoU) in the 
upper 1 0 cm of soil to 1 ..1% at 2 1 -30 cm depth. The total 
amount of soil carbon was estimated to be 12.3 kg C m~^ 
to a de|»di of 7S cm, amndng S8% carbon content of aoil 
organic matter (after Jackson, 1958) 

Calculations of the carbon pool present as canopy arthro- 
pods utlized weeldy measurements of population densities 
per leaf with conversion to a unit area bioriuss basis (Reichle 
and Crossley, 1967). Using the mean carbon content of in- 
tact tbsoe of 45%, carbon pools of canopy heibivores and 
predators were 101 and 27 mg C m"^ , respectively. Litter and 
soil invertebrates were estimated from population analyses. 
Litter invertebrates amounted to 520 mg C m'^ , whOe soO 
invertebrates (primarily earthworms. 6)(7<»/<j5(u/«) averaged 
6.4 g C m'' (Moulder and Reichle. 1972. McBrayer and 
Reichle, 1971). The mean annual carbon pool in total litter 
and son microflora based on A TP analysis was S8 g C m~^, 
with approximately 6S% in funci and 3S% in bacteria (Aua^ 
mus, 1973). 

Annua! Carbon F!tixr<: Fl:ixe<; nf carbon in net photosynthe- 
sis and autotroph respiration were determined under natural 
temperature and i^t conditions by means of gas exchange 
analysis in controlled environment thambers (Dinger, 1972; 
Retchle et al., 1973a). Data from several hundred hours of 
measorement were used to determine average daily and 
seasonal flux (ussumin^; a 180-day gmwin^: qcLison) in con- 
trast to the limited data employed in the earlier summary of 
caibon metabotim (Reichle et el., 1973a). Converting CO, 
fluxes to carbon resulted in a gross carbon uptake of 2. 1 5 
IcgC m~' yr~' . This value of total carbon influx is a minimum 
estimate of true gross photosynthesis in that light respira- 
tion of foliage was assumed aqint to dark respiration of 0.20 
kg C m~^ yr~' . Recent measurements of yellow poplar suggast 
that light respiration is approximately 4 times as great as 
dark respiration (Richardson efef., 1972). 

Respiration of lateral roots was estimated from mano- 
metric determinations and monthly biomass density (Reiciile 



er of., 1973a). Total annual carbon efflux firom this com- 
partment was 0.392 kg C m"' yr"' . Estimates of shoot 
respiration are based on data of Woodwell and Botkui (1970). 
Total carbon loss by branch-bole tissues was 0.660 kg C m~' 

yr"' . Preliminary analysis of woody shoot respiration of 
Liriodendron suggests good agreement with their data. 
Foliage respiration evolved at least 0.4(X) kg C m~' yr~'. In- 
cluding minor contributions from forest floor autotrophs, 
total autotrophic respiration was 1.44 kg C m"* yr"' . 

Total heterotrophic respiration from the forest floor was 
measured for 24-h intervals througii the year using gas 
analysis procedures (Edwards and Sollins, 1973). Carbon 
evolution from the forest floor was 1.04 kgC m"' yr"' . 
Decomposer respiration from Utter was estimated to be 0.21 
kg C m'' yr ' . b.ised on monthly estimates of pool size and 
respiratory flux per unit weight determined manometrically. 
Respiration of canopy-feeding bisects was estimated from 
body size-mctahoiism regressions (Reichle, 1*^71 ) and mean 
body size for each age-class for the various insect species. 
Sununed canopy insect respiration (herlrivoroua and preda- 
tor> ) was 0.OT4 ? V m'' yr"' . 

Annual littetiail averaged 229 gC m"' . Leaves accounted 
for 78% of annual Htterfall. Over the eight-year period (1962- 
1970), tree mortality determined from stand inventory was 
assumed to have occurred at a uniform rate, 50 g C ra^ yr'' 
(Sollins et al., 1973). The loss of photosynthetic surface area 
through insect consumption varied by a factor of nearly 2 
over a three-year period. Actual foliage consumption varied 
ftom 1.9% to 3.4%. whde actual nsdoetion in photosynthetic 
surface due to hole expansion rangld from 5.6% to iO.1% 
(Reichle et al., 1973b). Using a mean carbon content of 
leaves of 50%, the carbon flux due to actual consumption 
wna4JgCm''' yr'*. 

DiSCUSStON 

Carbon Rml^rt Comparisons and Implications A total car- 
bon budget provides a basis for estimating ecosystem metabo- 
lism (Figure 2). Based on mass bahmce calcufaitions and field 

determinations, a lower bound on gross photcKiy nthesis was 
taken to be 2.1 5 kg C m"^ yr'' , net primary production was 
esthnated at 0.716 to 0.752 kg C m~' yr'' (baaed on gas 
analysis and allometric estimates, respectively) and net eco- 
system production was 0.046 to 0X)82 kg C m"' yr" ' . Auto- 
trophic respiration (R^) was estimated at 1 .436 kg C m"* 
yr"' and heterotrophic respiration (Ri^) was 0.67 kg C m'* 
yr'' . Heterotrophic biomass of <60 g C m'^ contributed 
31% of ecoqrstem respiration (R;^ ■)■ R|{ =2.11 kgCm"* 
yr'' ) due almost entirely to decomposer activity. 

Analysis of ecosystem metabolism provides insight to 
overall dynamics and relative importance of the separate com- 
ponents. Another comprehensively analyzed ecosystem is the 
xeric, oak-pine forest at Brookhaven National Laboratory 
(Woodwell and Botkin, 1970). While obviously differing 



'^'^[.'•j I lyi lied tnaterial 



120 



stnictunlfy from the LIrkklendron forest (compare total 

standing crops of autolrophs. Table 1 ), the two ecosystems 
had itanilar net primary production. Relative production of 
the two systems also is sfanHar. The observed variation be- 
tween the two forests is within the rnrpe i-rbsep- eii tToni 
yeai-lo-year williin the same ecosystem (Harris, unpublished 
data). Autotrophic respiration (R ^ ) of the two systems is 

similar (see Table I ) nu- ditfcrcnccs in metabolism are in 
heterotrophic respiration CRji^* for the yellow poplar 
forest was more dian twice diat of the more xeric forest at 
Brookhaven (Table I). The large and relatively larger R|| 
of theydlow poplar forest resulted in total ecosystem 
le^pication (R^) of 2.11 kg C m ' yr"' (2.08 times greater 
than the aak<pine forest). Basic to these differences is the 
apportionment of between R nnd R|j . the ratio of 
R^/R|j for the oak-pme forest was 2.5 (only 0.68 in the 
yellow poplar forest). The larger R^^ of the yellow poplar 
forest represents annual decay of 7 1 2 g C m'^ y f ' . while 
the oak-pine system loses 360 g C m^ yr' ' . Comparison of 
the ratios ofNBr to total standing crop (OjOS for oak-pine 

ar^d 0 007 for vcllow poplar) indicates that thiC Oflk-pilie 
system is accumulating carbon 7 times as rapidly as the 
yeOow poplar forest. Thus, while euraory examination of 
single components of ecosystem metabolism would suggest 
overall similarity, in fact these two systems are quite dif- 
feient. Bcocystem analysis malces these differences readily 
apparent. Additionally, the value of Rj, in the l.iriodendron 
forest confirms the existence of a high root tiunover rate; 
decoinpoiition of 222 g C m"* yr'* from Htterfall, tteid 
bole and frass inputs is substantially les.s than 712 gC m** 
yr"' in decomposer respiratory losses. The difference is wdt 
within the range of an independent estimate of root turn- 
over, 375 g C m"' yr"' . 

Cartfon Residence Times Interpretation of the global carbon 
cycle requires understanding of the ecological factors affaetF 
ing carbon turnover in local and regional terrestrial eco- 
systems (Olson, 1970; Anonymous, 1970J. Residence times 



TABLE 2 Turnover Rates and Residence Times for CwiMn 
In the Uriodendron Fofett at Oak Ridge, Tennessee. Turn- 
over Rates (yr~^ I Are Calculated from Flux (g C yr~^ ) 
Divided bf Compartment Size (g C m'^l 





Turnover 


VlL-Lin 




Ral«* 


Residence 


Compartment 


tyt ) 


Times (yr) 


Rapidly decompoiiiltelltlarlUi 


0.89 


I.l 


Lateral roots* 


0.49 


2.0 


Atwvcground woody camponent 


(J.(>()64 


IS6.0 


Total woody compOMat 


0.049 


aouo 


SaVoqiBnic matter 


tuami 


t07.0 


Pomt flcoaysiem 




IOjO 


*Tiitaovar rate uicalalad tnm tM 


a or R£ (total cart 


ton oflluxl to 


total ocoyrtMB cuton pool. 
^Lateral raois an aH raotaewept • 


iMcantralatmBp. 





of carbon in components of the Liriotlendron Ibrcst eco- 
system vary considerably depending in part upon rates of 
carbon efflux and caibon pool sizes. Components audi o 
foliage have turnover times of one year or less (Table 2). 
Our data indicate a surprisingly rapid turnover rate of lateral 
roots of 0.S yr'* (a residenoe time of years) largriy at- 
tributable to sloughing of roots <0.5 cm diam. Other com- 
ponents of the forest ecosystem have much longer residence 
times. The turnover rate (9.3 X 10~' yr'* ) of soil carbon In 
the Liriixiendron forest represents a residence time of 107 
years, witile turnover of carbon to litter through mortality 
ofwoodytfeeslsabodow(SOgCm~' yr~'/699gCm~' ■ 
6.4 X 10*' yr'* ) and represents a residence time of 1 SS 
years. The values of carbon residence time agree reasonably 
well with those reported by SCEP (Anonymous, 1970). The 
companthreiy long residence tfoMS of both of these pools 
suggests that forests have a large capacity to act as a carbon 
"sink," thus buffering increments to atmospheric CO2 con- 
tent, but only for a few decades as decomposition of a 
larger detrital pool would return increasln^y larger aOHNHItt 
of carbon dioxide to the atmosphere. 



TABLE 1 Comparison of Metatiolism and Structure of Two Tarreitrtat Ecotystems. Units of 
>afa hgCm'' and IcgC m~' yr'^ for Cmnpartmants and Fhnies Unlees Otfierwise Notad 



*ilevlwd aflar Rekhla ei aL, l97So. 
♦Wtoo d waB amd Botidii. 1971k 



Ruamcttar Liriodendron Fotest" Quercus-i^nus Forest^ 

TMal Handing crop (TSC) 8.T61«Cm'' S.W^Cm'* 

Net primary production (NPP) 0.73 kg Cm"^ yr'* IK60 kg C m"* yr~* 

Relative production (NPPATSC) 8.3% 10% 

Autotroph rsiptation (K^) 1^ 0.68 

R^/TSC M6 0.11 

Heleratraplireipitatiaa<Rj{) OidY OM 

Epaeymm reipiiatton (|tg;"Rj|,*Rt|) 2.11 1,01 

Net ecoayatem pcodwctlon (N&*Nfr.Kn) Oj06 IkU 

0.70 0.» 



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MALVmOr CMWON PMW AND mOOUenVITV IN A TMNIMTI MClOUOUt POHEtT iCOCVSTEM 



121 



When the forest eoosyttem is viewed as a sin^e entity, 

the overall residence time of carbon is only 10 yean (2.1 10 
gC m'* yr'' /2 1 ,1 50 g C m ' ^010 yr'' ). This more rapid 
turnover is the result of the large respiratory efflux. Viewing 
thesyitam in this manner detracts from the idea that forests 
act as long-term carbon "sinks." These data suggest that cat- 
bon residence time in ecosystems can be manipulated 
throu||idMn|eslneo(Mysteni napintion (R^ = Rh)- 
Thus, maintenance of younger forests with relatively high 
iKt primary production but witti luwer autotroph mainte- 
nance lespifation and smaller detrital pools cotdd result in 
increased carbon residence time in the biosphere (compare 
NEP and annual decay for forests in Table 1). Clearly addi- 
tional aununailes of carbon mataboilian of Averse eooqritsin 
types lie needed. 

Experimentii Constrdnu Estimates of carbon dynamics of 

ecos> stems are extremely sensitive to the accuracy of 
measurement of component processes. Some eco^stem 
pmnieters can be deteraiined directly as well as from 
meaaitrement of physiological fluxes. The degree to which 
these independently derived estimates corroborate one 
another is the only present check on accuracy and precision 
of uur measurement techniques applied to total eco^slema. 
While estimates of autotrophic processes in our forest seem 
reasonably well detmed by harvest techniques and measure- 
ment of physiological fluxes (NPP of 750 and 720 gC ra"' 
yr~' , respectively ), the difference between the two estimates 
yields values of net ecosystem production (.\KP) which 
differ ipproximBtely two^foM (Hgme 2). Thus a S% dif* 
ference in estimates of autotrophic processes is magnified 
20-fold in esiunation of NLP. Additional summaries from 
other IBP research wiO dariiy the range of likely estimales, 
precision and accuracy of methodologies, and perhaps lead 
to greater standardization of techniques and analysts. 

Estimates of carbon residence times, and particularly 
measurements of carbon efflux and carbon pool sizes, also 
are subject to close scrutiny. In the present example, a 25% 
change fai estimated carbon effhix (R^ Rh). or total car* 
bon respired by the ecosystem, results :r a change nf similar 
magnitude in carbon residence time. Because of the large 
pool of carbon, variations in estfanates of net carbon aoctunu- 
lation (M P or NPP) have little influence on estimates of 
residence time. Our data ernphasi/e the importance of ac- 
quiring estimates of respiratory (bodi autotrophic and 
heterotrophic) fluxei for diverse types of terrestrial eco- 
systems. 

Budgeting of ecosystem resources follows the principle 
of conservation of mass. Our present summary of hetero- 
trophic metabolism is based on the assumption that total 
soil carbon efflux is 1 .04 kg C m"' yr"' . Estimales of litter 
and root decay and maintenance of living roots were sub- 
totaled. The dift'erence, I ! 5 g C m'' yr"' , was attributed to 
the decay of soil organic matter. The accumulation and turn- 



over of soil carbon may be a major factor determining the in- 
fluence of terrestrial ecosystems on the atmospheric carbon 
balance. Therefore, direct measurement of, as well as knowl- 
edge of the factors controlling, the tnetabolism of soil carbon 
are laquited to aaaen this important rale of tenesttial eov 
systems. 

Another carbon llux requiring further analysis is the 
humiflcation of detritus. This flux represents the internee 
of cycles of carhop and other eletiients. Measurements of 
in siiu humiticatiun are at best approximate, and the chemistry 
involved is only incompletely understood for even die 
simplest nf systems. While nietfiodolngy and data associated 
with estimation of component processes arc subject to 
(brther analysis and intetpreiation. the fact lemains thet 
large variances will be associated with estimates of metabolic 
parameters of total ecosystems even though component 
processes may be known within 5% of their real values. Con- 

fidence in estimates of ecosystem metabolism initially can 
be gained through systematic comparison of results of cur- 
rent IBP smdiet at we await development of improved analyti- 
cal techniques. 

REFERENCES 

Anonymoui. 1970. Man's iaqnct on the globai environment: Aimh- 
nmt snd recomnwndstiom tot action. Report <rf' the study of 
critical envtroflinental praUaaM CSCEP)l Ike MIT hen. Cui* 
bridge, Mass. 319 p. 

Au>niu% B. S. 1973. Litter and soil microbial dynamics in a de- 
ciduous forest stand. EDFB-IBP-73-IO. Oak Ridge Nauunai 
LalMratory, Oak Ridge, Tcnn. 184 p 

DiniBW. B. E. 1972. Gimous exchanee, forest canopy and meteor- 
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Edwards, N T . and P. Sollins. 197? rtmtinuousi meaniremMtef 
COj cvoluiion from partitiuntd lutcsi flour components. 
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Harris, W. F., R. A. Goldstein, and G. S. Henderson. 1973. Analysis 
of fofett Uomaai pools, annual primary production and mrnovgr 
of Momass fcr a mixed deeiduaus foiest. p. 43-44. /« H. E, 
Yonng (ed.) ItlPRO Symporium: Poreft tnomis. Univ. tbine 
Press, Orono. 

Harris. W. I-"., R. S. Kinerson, Jr.. and N. T. (-Edwards. In prcvs. Com- 
parison of lielowground biomass ol riLitural deciduous forests 
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Horlon. A. P., W. D. Shulls, and A. S. Meyei. 1971. OeteimiiiitKm 
of nltraien Mifltt. i^eiplMtn sad earben in soiid eedoilal 
materials via hydraaeBatkm and cleBWii l la le c t l t e deteeliaa. 
Anal. Utters 4:61 3-421. 

Jackson. M. L. 19S8. Soil lii iiii il i—1yili rfimliri fliH. Inn , 
Lnglcwood Uiffs, .N.J. 498 p. 

Kolesnikov, V. A. 1968. Cyclic renewal of roots in fruit trees, p. 
102-106. iH M. S. Ghilarov, V. A. Kovda. L. N. Nmrichkowi- 
Ww0Ka.l. B. Rodin. aadV.M. 9wimilM«a(«ds.)lletliads 
oTpiedaellvliy sMdias in root tystemt and rhteospheie oi|a> 
vinnt. Intematkmal lymperinm. USSR, August-ScpMnbai 
t9f,K tiSSK AljJ o! Scis. Naukj, Leningrad. (RtpllMed Iv 
Biddies. Lis., Guildford, U.K. 240 p.) 



oopy I lytiiC'u niaiufial 



122 



W.F.IMIIRttMal. 



McBrayer. J. F.,andD. E. Reichlc. 19"! Truiihii slrjclurc and 
feedir^ rates or forest soil invcrtebrjcc pupulaliuns. Oikos 
22:381-388. 

Moulder. B. C, and D. £. Reichle. 1972. Sipiificanoe of «pidtr 
prcdttion is Ibc eociiy dynamlci of foNM fkMV ■ribraiMd 
coniinunitics. EcoL Monogr. 42:473-498. 

Olson, J. S. 1970. Carbon cycles and temperate woodlands, p. 226- 
241. /« D. E. Ri-ichlf ud.) Analysis of temperate forest eci^ 
systems. EcoJugicuJ studies 1. Springer-Verlag, New York, 
Heidclbcri;, Berlin. 

Reidile, D. E. 197 1. Easfgy ud mttdent meutioUim of toU uid 
linn i»«tafenlM,pw 465-477. Jii P. OmipiMiid (idj Ptadiw 
tMly of fiiwwt tCMyilmiia PiooMdingii BniMli SyMjMMhiin* 
Oelslier 1969. UNESCO, hrii. 

IUielll*.0. 1- , and S. 1. Aucrbach. 1972. Analyws of ecosystems, 
p. 260-281. /« J. Behnke (ed.) Future dircciions in (he life 
sciences. Oxford Univ. Press, New York. 502 p. 

Reichle, D. E., and D. A. Crossley, Jr. 1967. Investigation of heleio- 
trophic productivity in forest insect communitki, p. S63-587. 
In K. Ftlmtiwks («L) Secoadaiy pradnctirily of tctnitrid 
•e m in a im a , VoL II. ft oew din p of WofkbiB Meetiiig, JaMomt, 
1966. Polish Acad. Sci., Warsaw. 

Reichle, D. E., B. E. Dinger. N. T. Edwards. W I . Harris, and 
P- SolUns- 1973a- Carbon flow and storage in a forest ecosys- 
tem, p. 345-365. In G. M. WoodwcU and b. V. Pecan (eds.) 
Carbon and the biosphere. BtOOUltvetl SmWMlwn fal BMogT* 
A£CCONF-720Sia 

R«iiilile.D. E.. R. A. GoMrteiii. R. I. Vh Hook.«da J. Dodno. 
1 973b. Analysis of insect coMlunption In » foiMt C«IIO|iy. 
Ecology $4:1076-1084. 



Copyriydiuo rriaicrial 



Reichle, D. i , R V, O'Neill, S. V. Kaye, and P SoMitu 19^3 

Systems analysis as applied to modeling ecological processes. 

Oikos 24:337-343. 
RkhaniMn. C J., B. E. Dinger, and W. F. Hants. 1972. The lue of 

ftamlil nrfttaim, plio(ap4|nwii, hHnimi, mtav potential 

and radiation to cstiniate net pbotoQmtlieiii. EOFB-IBP-72-13. 

Oak Ridge National Laboratory, Oak Ridge, Tenn. 1 30 p. 
Sollins. P.. jiid R M Anderson. 1971. Dry-weight and other djU 

for trees and woody shrub* of the southeaiiern United States. 

0RNL-lBP-7l<<. Oak Rl^ie NatioMl Labontoiy.Orit lUdc«b 

Tcnn.BOp. 

SoOim. P.. D. B. RaiiMa, nd J. S. Ohm. 1973. Onanlc aattaf 
bUdftl Md atodal tm * aoMlUn AwahCMM Uriodendron 
foratt eDlni>lllP-73-2. Oak RidBB National Laboratory. Oak 

Ridge, Tenn. ISO p. 
Taylor, K C, Jr. 1974. Phenodynamics of production in a mesic 

deciduous forest, p. 337-354. In H. Lieth and F. Steams (eda.) 

Phenology and leaionality modeling. Springet-Veiiag, New 

Yoik.H«idalbeiK,BaiUn. 
HMttakar, R. H.. and G. E, Ucant. 1973. OHtam in the Moti. 

p. 281-302. /n C. M. Utoodwall Md E. V. ftcM (eda.) GHbm 

and the biosphere. BraoUMVan SjnRporfuB In BManr. ABC 

CONI-720510. 

Woodwell, G. M., and D. B. Botkin. 1970. Metabolkm of terrestrial 
etxnyatenu by gis exchaoie t ec h n iquaa: The Biookhav«n ap> 
pmadi, pu 73-W. /« IX E. RalcMe (ed.) Andy* of tempenle 
foiMt MoiyitanH. Bcolagicd ilndiea 1. Spiliwir'ViBil^ New 

m# Mfc- - 



PLANT NUTRIENTS AS 
LIMITING FACTORS 
IN ECOSYSTEM 
DYNAMICS 



C. O. TAMM 



INTRODUCTION 

A satisfactory model of ecosystem functions must enable 
Emulation of not only tteady itite conditions but also ef- 

fects of changes in nanipiilation or other external influences. 
Therefore, recognition of the various regulatory mechanisms 
in the system is (rf even greater importance than accurate 
description of processes within undisturbed ecosystems. 
While no one denies that lack of light, water, adequate tern- 
peiatures, or plant nutrienti may cut short the primary 
production of the ecosystem, thus seriously affecting all 
organisms depending on primary producers, few investigators 
iltve tried to explore the mechanisms involved in the adapta- 
Ikm of plant and animal communities to environnnents with 
a poor supply of certain nutrients. Experiences with field 
crops have initiated innumerable physiological studies on the 
effect of tnifooa plant nutrienti on growth and other proceoet. 
However, "nutrient deficiency experiments;" !iave become 
standard demonstration experiments, and the scientific 
frontier hat also moved in the diieetion of Mochemistry and 
molecular biology in plant nutrition work A few applied 
ecologists are still trying to explore the effect of fertiliza- 
tion on the species oompoaition of grass swardt, or the role 
of sewage nutrients in lake eutrophication Little Ulcnownt 
however, about how changes in nutrient supply afTect 
primary production, particularly in tenestiial ecoByatania» and 
next to nothing is known about the affectl 00 lecondaiy 
coruumeri and decomposers. 

The concept of Hmitfaig factors dates back to Ueblg's 
work of about 1840. His idea was that yield was proportional 
to the most deficient dement, as long as this element was 

123 



*'fai minfanum.** Later experience has Aown that LieMg'a 
**law of the minimum" was an oversimplification. Yet there 
an cases where his theory, as well as Blaclunan*s somewhat 
similar theory for factors lunlthtg iriiotosyntfaesis. describes 

fairly well what happens. The next great step was Mitscher* 
Uch's exponential equation for the relationship between 
added fertilizer and hanrest-the "law of dhninbhing re« 
turns." In its original form, this well-known curve accounts 
only for growth increases up to a certain maximum or 
"optimum." It b fairly simple, however, to include a factor 
which causes the harvest to decicMe when the independent 
variable increases above some optimum. 

Three-dimensional diagrams are one way of illustrating 
Mitscherlich curves, wtien two faldependent variable are in- 
volved, hut it is often more convenient to show a series of 
curves (Figure 1) (Nielsen, 1963). bvidcntly the growth of 
a grass award depends on both nitrogen and irrigation. One 
consequence of this conclusion is that the respons<' to 
fertilizer may be very different in ditlcrcnt years, owing to 
changes bi (necipUation. In other cases, differences in other 
climatic factors may interact with nutrition, e.g.. the length 
of the frost-free season. Therefore, field experiments with 
plant nutrients must be repeated, prefbraUy over a series of 
years, before contldcncc in the results can be established. 

Logistic functions, such as the Mitscherlich equation, are 
more laborious to woric with than are simple parabolas. The 

latter type of relationship is often satisfactory within a 
limited range but extrapolation may be very misleading. 

Different plant spedes react differently to environmental 
influences with plant nutrient supply being no exception. 
An ecologically important difference Is that between plants 



Copyriytinju rriaicrial 



124 



CO.TAIMM 



LiMl of IrriflMion 

518 mm 
432 mm 

374 mm 




3162 310 620 930 

/V APPLIED (kg/ha/yr) 

FIGURE 1 Than«poMlofariMis«rNo(ty«gn«gre«miM 
m M ft tawli flf liii^BtlQii 



having symbiotic n.xa'.ion ot nitrogen and those other plants 
which do not. This ditterence is also valid for whole plan! 
conununities with md wMiout lulroBBn^fixiog ipecio. Grait> 
clover mixtures react less to nitrogen aipply than do pure 
glass swards (Whitehead, 1970). 

As fiv as more natuial vegetation is eoncemed, much 
less is known about the requirements of dilTcrcnt species. A 
classical paper in forest science is that by Mitchell and 
Chandler (1939), where a number of Northeastem dcdduous 
trees were classified as nitrogen-dennrndin^:. nitrogen-toktnnt, 
or intennediate. Work was done with foliar analysis com- 
bined with field experhnentt in which nitrogen was supplied. 
A number of New Fnj^Jand forest sites were kLissiricJ with 
nqpect to their nitrogen regime. A conclusion Irom this work 
(Mitehdl and Chmdler, 1 939) ii Ihit ttw nitrogen regime 
must be one of the main factors In the competition l)etw«en 
tree species. Nitrogen-demanding species will be poor com- 
petitors on sites willi a low level of available nitrogen. The 
less exacting species, however, will not be able to take full 
advantage of a fertile soil 

On the other hand, it dues not necessarly follow that 
nutriant dioulation on a particular site must be differaot 
in a pure stand of a nitrogen demanding species from that 
occurring in a stand of a nitrogen- tolerant species. There are 
I difreienoes, but Ovington (19S7. 19S8) has 



shown that the most decisive factor for nutrient uptake by 
a tree species is its growth energy under the prevailing con- 
ditions. This b a result bi good agreement vrith more physi- 
ological investigations by In^csiad (1962). It is a well-known 
fact that nutrient uptake by plant roots does not always re- 
flect the nutrient demand; there is often a luxury consump- 
tion of ions in excess. DiUcrent plant species have varying 
abilities 1(1 abso'b and nccumulale different elements- both 
essential ones and othcrs-but this discrunmation is never 
complete. Therafon, studies of nutrient dreulatioo within 
an ecosystem usually reveal relatively little about the nutrient 
status of the various plants within this eco^stem. Full ad* 
vantage from nutrient circuUtion models cannot be derived 
until it has been complemented with information on the 
extent to which the nutrient demand in the dominant orga- 
nisms is satisfied (usually the primary producen). 

EXAMPLES OF NUTRIENT DEFICIENCIES IN FORESTS 

AND PEATLANDS 

Before proceeding further in the discussion of the mechanisms 
behUid the concept, 'limiting factors.** eommenu wfll be 
made on some typical cases of deficiency in one or more 
nutrients. It has long been known that lack of nitrogan may 
limit growth. Northern coniferous forests on medium and 
poor sites are one example, as shown first by Hesiabnan 
(1937) and Rome!! and Malmstrom (1945). 

An equally well-known case of deficiency in available 
nitrogen concerns heathland afforestation in Biitian 
(Zehetmayr, 1960). Growtb chocl< in spruce is common there, 
while other species, such as pines and larches, appear able to 
obtain more nitrogen from the sol bi Hw cariy stagss of af« 
forcstati<ni Tlie significance of this difference is probably 
that soil microbiological conditions, including mycorrhiza 
formation, provide an important regulatoiy nwchaniam for 
nutrient uptal<e by trees, and that some trees, or their mycor- 
rhizal fungi, are more sensitive than others. In Australia, 
iffBueerii species behive in much the nme way as spruce in 
European hetthlmd plantations (Richards and Bev^fs. 
1969). 

A number of cases of nutrient deficiency can be lelatod to 

man's activities. A deficiency in nitrogen in a forest may be 
the result of Utter removal. Such an operation was practiced 
for centatlH bi many Central European fbreits. 

Infertile soils, low in both total and avaflable nitrogen, 
may be the result of repeated or particularly intensive forest 
fire. In other circumstances, forest fire or prescribed bum- 
ing may, both in Scandinavia and elsewhere, help to maintain, 
or even to restore, the fertility of a forest site This is ob- 
viously the case m the southeastern United States, where 
prescribed burning soon leads to invasion by nitrogen-fixing 
leguminous plants. 

A^icuitural use tends to deplete the soil of organic matter. 
On sandy soils, soil organic matter is often the only cation- 



Copyrighted material 



nJkHT MUnrmCNTB AS UMmNO MCTORS IN ECOSYSTEM DYNMMCS 



125 



absorbing complex available. Therefore when fields are 
abandoned for cultivation and planted with trees, destruo* 
tion ut the ireanic matter may lead to « deficiency in potas- 
sium, or magnesium, or both. 
Dninaga of a peatland means a iMoround dumge in the 

nutrient regime. Many jjeatlands receive f;ome plant nutrients 
from floodwater during rainy periods. Tliis supply is cut oil 
by ditching, and tlie water movement in the root-aone is 
changed from predominantly horizontal to vertical. Potassium 
deficiency is a common consequence of change in the water 
and nutrient raglnw. Deficiency in phoaphonu is also com* 
men on drained pcatlands, when- a low content of phos- 
phorus is often a characteristic feature. Lack of phosphorus 
and potasrium on diainad peatlands limits not ca&y tree 
growth but also the production of the ground cover. 

The fact that drainage of a peatland may disturb the 
nutrient alattts by no means implies that undrained peat> 
kndtan nomially well supplied with nutrients. Few experi- 
ments have been carried out, but there is evidence that defi- 
ciency in phosphorus may occur on undrained peatland 
(Tamm, 19S4). Potassium and nitrogen also may well Umlt 
production. Gore (1972) has worked out an interesting 
mathematical model for an ecosystem on blanltct peat, 



dominated by triuphuntm vaginatum. I hc experiment con- 
sisted in the removal of vegetation by repeated clipping for 
several years, and the model suggests that the production of 
Eriophontm vaginatum is limited by available phosphonu. 

In die case of gnsdand,itis(|uiteclearflMt1heapplica' 
tion of Tiiiirients may increase productivity. TUiiawdl 
demonstrated by the results from the German IBF pfqjeet 
in Soiling (Figure 2). There an Indications that fertUnttoo 
with nitrogen mny he replaced tn some extent by lymMotic, 
and perliaps also asymbiotic, nitrogen fuation. Production 
and nitrogen turnover may be sU^ily lower in a grav/clover 
mixture without fertilizer nitrogen, than in a pure grass sward 
receiving large amounts of nitrogen, but so are leaching losses 
(see Figures 4-7 in Whitehead. 1970). It is hoped that the 
final synthesis of the lir grasriand work will died more light 
on tlieae problems. 

HOW iMaH OF NUTRIENTS RESTRICTS PRIMARY 
PRODUGTION 

The last section of this paper will be devoted to an ad- 
mittedly very incomplete discussion of the mechanisms by 
which nutrient deliciencies may limit ecosystem primary 




FIGURE 2 Enargv fixation in rwt primary production in 
I frani SdUna P^OlaB^ luppltod by M. Rynas. 



I I Litter (in fortst 



I 1 Gr»wip«tt 
■■ Bark 



Rootii, ^ g iMn dtam. 

Fine roots 
* Oiff«r«noe Maximum- 



4-f Eitimtted from da* 
compoution intmltl 

CakuiaM for roots 
m2Hnmdiiin.only 



nghne M(, NPKI and 



Copyriyliicu iiiaiorial 



126 



aaTAMM 



production. Some of this discussion will be based upon work 
canied out within the Swedish ii!P program. This is out of 
necessity since relatively little experimental work huyvt 
been completed on plant nutrition within the IW-VT pro- 
gram. 

A dosage experiment was started in 19S7 with nitrogen 
MippHed annually to a young plantation of Norway spruce 
on an abandoned Held an experinimt that was la(cr in- 
coiporated into the Swedish IBP program. Half the number 
of plots also received a combined P, K fertilizer. This experi- 
ment was never a fully integrated ecosystem project, but 
biomass data are available from two inventories and primary 
production data, together with much other information, 
from the Hnal sampling in 1969-1970 (Table 1). 

One objective of Ihi? experiment wa< t<> study what 
happens in a stand when ditterent nitrogen levels are main- 
taUied over extended periods of time. There has been some 
variation in interna! nitrogen level in the spruce, but on the 
whole the experiment was successful in this respect (Figure 
3). At fint there was also a positWe response to nitrogen, as 
assumed on ihc basis of foliar analyses he-forc tlie start of 
the experiment. An optimum curve for total stem produc- 
tion versus foliar nitrogen level was obtaiaod, togNher with 
some evidence fur an interaction between N on the one hand 
and P. K on the other (Tamm, 1968). 

A parallel experiment was laid out in another plantation 
of the same age. planted on forest land. There was no posi- 
tive response to nitrogen in this experiment for the iirst re- 



vision period. The reason is no doubt tfie sixalled assart 
effect: the tVrtilLzing effect of tlic removal of the old stand. 
On good sites this effect may be both strong and long-lasting. 
I advise against the uncritical supply of nitrogen fertilizer 
to recently established saplings on former forest land. The 
assart effect, particularly intensive after forest fires, often 
malies fertilization unnecessary for some time. 

Returning to the experiment on the old field, the total 
amounts of fertilizer added during the 13-year period were 
very large (Table 2). The originally positive response to 
nitrogen ciianged to a negative one-at least at tiie higlMr N 
levels There remained a significant P, K-N interaction, mean- 
ing that F, K alone has nu effect, while N, P, K fertilization 
is coosistenfly better than N alone. At the end of the expeii- 
mcnt there was no intiicarjon that prnwth-rate was higher on 
fertilized plots than on controls. Stem growth was lower at 
high N (Fignre 4), whUe total prrniary production appeared 
to differ little between must treatments (Table 3) 

The interesting point here is that needle biomass was 
much higher on N fertilized plots than on controls at the 
binniass sampling in 1'560 (Table I). In 1970. however, there 
was hardly any difference in needle biomass between plus N 
and minus N. Moreover, the N plots had Increased their 
needle biomass very little from 1960 to 1970, while the 
minus N plots had increased their needle biomass by more 
ttian SO percent. Ilieae data support the assumption that the 
main effect of the nitrogen fertilization was to allow the 
spruce to build up a large crown more rapidly (cf. Brix and 



TABLE 1 Blnman ttapismbar 1900 and May 10701 «# a Spniea Oiand PlaMad In 10«7. EnpwInMnt El Hdfeabwv^ 







O 


K 


Nl 


NIK 


N3 


N2PK 


N4 


IMFK 




1)56 


26 


20 


20 


25 


22 


23 


22 


22 


Mean hejjiht (cm) 


I9SC 


186 


163 


158 


181 


167 


172 


165 


172 


Stem vekune teJua') 


two 


27 


20 


26 


35 


31 


33 


31 


33 




1970 


143 


12S 


130 


171 


145 


160 


137 


152 


Oiy wdiltt Oig/ha) 


I960 


8,520 


6,920 


8,740 


10,530 


9.680 


10,760 


10,340 


10.700 


stsm wood 


1970 


40.060 


3S.380 


38,490 


49.090 


43,520 


47,570 


41460 


45.740 


Slmbaik 


1960 


1.730 


MOO 


1.760 


2,120 


1,960 


2,170 


^100 


2,160 




1970 


6^00 


5.720 


6,260 


7,760 


6,970 


7,360 


6.770 


7,260 


Branches 


IWO 


7,510 


6.570 


9,200 


10,480 


9,920 


10,880 


10,610 


10,680 




1970 


12,860 


1 1.1 'JO 


11.020 


15.190 


12.470 


14,490 


12.110 


13,980 


Nccdlei 


I960 


8,680 


7.560 


10.840 


12,310 


11,670 


12.790 


12.480 


12,540 




1970 


13.400 


11.770 


11,5 80 


15,530 


12,940 


14,900 


12.680 


14,360 


SuraalMVB 


I960 


26.430 


22^50 


30,540 


35.440 


33.230 


36.600 


35430 


36480 


ituaapt (kg/ha) 


1970 


72,730 


64.060 


67,350 


•7,570 


75,900 


84420 


73420 


81440 




1970 


2490 


2,160 


2J80 


2jao 


2.610 


2420 


2470 


2.700 


Roots > 5 mm diam. 


1970 


11.070 


9,180 


9,8S0 


13,150 


ia9to 


12.130 


10.780 


12.170 


Rucits ^ linn dim. 


1970 


4.740 


4.740 


4,740 


4,740 


4.740 


4,740 


4.740 


4.740 


Totai biomau 


1970 


90.920 


80,140 


84,320 


108,340 


94,160 


104,210 


91410 


100,950 



NOTE: tMWghts abone stuaipi wllmaStd by ■mm of ■ ■mm m m mi Is on Maple tiaM fkea ill inatflMiits and ■lloBMfic oqaaHoM (la cim of 
>wa>M Md MSdlM d W ii i a M e^aelieM fee »W wtd -Hi. »tmv wrigMs and of looti > S mm 6Mad am oatf IS MMpto Mm aad 

MMUWii illanctriG «|mIIom. RoMa < S mm MttaMled IroM MMple filt: no d M fcuiKO ti t w— tnatmmU MUNMiad, to r a m i of wkl* 
MaHMtag; Biomau depends both upcm ■xpMlHWHi iMaMwls and oe mud coiidWoii a> mrt of eapitont, vdrich may be eaytiHid m 
•wa»«iaad Bi^rgung lades, >/r X H (n ■nnb«rartnM|Mrplat,Ha|btlrMMab«|ghl 1«S6). 



PLANT NUTRIENTS AS UNITING 



FACTORS IN eCOSVSTIM DYNAMICS 



127 




Ebell, 1969). The ultimate size ot' the green crown on this 
dte seems to be determined by other factors than added 
nitrogen, and therefore the fertilizer ctfet.' [■^ not persistent. 

The effect of plant nutrient supply as the lactor Imiiting 
ibn mount of photoqrnflietically active orgms is probably 

the most common, and the simplest, mechanism by which 
tltis factor limits primary production. In ecosystem modeUmg 
it should be observed tint this mechanism automatlcSlly 

leads to a lag between nutrient uptake and nutrient effects 
on primary production. Depending on the plant species and 
the element examined, the length of the lag may vary, as 
different species and different growth forms iray have vary- 
ing ability to redistribute a particular element in their tissues. 

Another Indication of the exbteoce of the same mecha- 
nism of growth limitation can be taken from an old Swedish 
experiment. Here wood ash was used to stimulste forest 
growth on a drained peatland that remained at a very low 
productivity without fertilizer. After additions of wood aril 
in 1918 and 1926, birch sunds established themselves. 
Various amounts of wood ash produced different amounts 



of forest growth, both tuljl and jniiual (i'tgurc 5). Initially, 
there were large differences in nutrient concentrations be- 
tween treatments, but m time these differences decreased in 
the case of potassium alntost to nil (Figure 6). Potassium ap- 
pesis to be dw dsNMnt **in mtabnum,** to use UeMg't 
terminology. Evidently the stand adjusts its growth veiy 
closely to the amount of available potassium. 

Other mecbantans are also operating, when nutrient sup- 
ply limits plant growth. It is evident that the cMorotic 
needles on some sites that are deficient in nitrogen or potas- 
sium must have a photosyndietic capadly below normd. 
Yet it is not too well known to what extent less spectacular 
deficiencies affect photosynthesis (Keller, 197 1 ; Brix, 197 i , 
1972). 

It has been suggested that a deficiency in potassium af* 
fects the water economy of plants (Arland, I9S4: Brag, 
1972). It is certainly true that deficiency in potassium, or 
perhaps rather an unfavorable ratio of K/Ca, affects winter 

survival. Furthermore, the possibility shoiild not he overlooked 
that a nutritional imbalance may attcct the redistribution of 



TABLE 2 MulriaaSi A«M, 1t67-1M0 (hgAwl in Experiment El MMnheri, RemnliigMoip 





Treatment 














0 


nc 


Nl 


NtFK 


N2 


N2PK 


N4 


N4PK 


M 








62S 


1,550 


1,550 


3.900 


5,900 


P 




151 




ISl 




151 




ISl 


K 




790 




2n> 




200 




200 


Ml 




300 




200 




200 




20O 



128 C.O.TA«IM 



Control 




I I I I r I I I I I 
mo IMS IMf 



TABLES AniMMlPradiNtionbyllwSpniwttMidinTiUiKkifri) 





0 


nc 


Nl 


NIPK 


N2 


N2nc 


N4 


N4PK 




3^280 


2,960 


2.920 


3.770 


3.310 


3.630 


3.170 


3,500 


BlWKllCt 


3.160 


1,950 


2.020 


2,600 


2.300 


2.520 


2.200 


2.420 




4^60 


4.2M 


2590 


4330 


4.110 


4400 


3320 


2.630 


Sliiin|W 


240 


230 


210 


2S0 


210 


220 


190 


180 


Roots > S mm 


1.860 


I.SOO 


1.800 


2.260 


2.020 


2.050 


1,950 


2,200 


Roots < S mm 


1,070 


1. 1 00 


1,100 


1,060 


1.110 


1,060 


1.100 


1,060 


TOTAL PRODUCTION 


13.270 


12.010 


12.040 


14.790 


13.060 


13.780 


12.130 


12,990 


OnwMwadhtdWI) 


2jsm 


24S0 


2.2$» 


2SW 


3.S60 


3410 


2^50 


2.710 



NOTF: Stem production and current needles detennincd on tample trees from all treatments. Ratio between 
on one liaiid current needles and on the other hand needle production (-lait yearv needles) and branch pro- 
duction dciirinincil on 1 2 sample trees from Ireatmenti O, Nl.and NII'K Stump pr' .Im tion astumrd in he 
proportional to item production, roots < 5 mm to branch production (same ratio biomau:production) and 
iMtt > S mm lo madia protocUon. 



Copyrighted material 



PLANT NUTRIENTS AS LIMITING FACTORS IN ECOSYSTEM DYNAMICS 



129 




photoiynthetk products and other metabolites in the plant 
and hence affect growth. In luci. there is some evidence in 
the spruce experiment described earlier, thai nitrogen over- 
doses affected stem growth more than needle production. 

CONCLUSION 

It Is hoped Alt the lynlhealt of the IBP work within the 

various biomes will supply more examples of the cl<5se rela- 
tionship between nutrient supply and growth. Analysis of 
extreme iltiiBtiooi,diie to variations eldier In son or in 
weather, may be helpful in this respect. Still more experi- 
mental worlc will be needed on the mechanisms by which the 
plant nutrient sopfily Omtts growth-both in the form of 
physiological studies in the labotatoiy and ecophydotogical 
research in the field. 

In conduihNi a ihort preientatlon will be made of some 
results from recent experiments started under the auspices 
of IBP but not yet completed, to illustrate one type of Tield 
experiment needed. A strong reaction to nitrogen was 6^ 
tabled in the qmioe growing on a poor site (Figure 7). Phos- 
phorous supply also increased growth, although to a much 
smaller extent than did nitrogen supply. The effect of other 
pbdll nntrienti still remains obscure. A preliminary optimum 
curve was obtained for nitrogen (Figure 8), and there has been 
a dramatic change in production in both spruce and ground 
vegetation. On the other hand, feitlUution caused increases 



in winter damage and in vertebrate browsing. It is certainly 
necessary to take the entire ecosystem into account in both 
planning and interpretation of field experiments. 

It makes no difference whether the ecosystem is a forest, 
• tundra, a grassland, or a desert. The breakthrough for this 
integrated way of looking at ccfilogical problems is certainly 
one of the major achievements ot the International Biological 
Ptogianii 

SUMMARY 

This paper reviews early work in plant nutrition, and describes 
a few cases when lack of nitrogen, potassium, or phosphorus 
restricts the growth of certain or an primary producers. While 
nutrient cycling studies form a well-recognized component of 
eco^stem analysis projects, it is also necessary to investigate 
the nutrient status of the dombrant primary producers. WMi- 
out such information it will be impossible to forecast effects 
of changes in nutrient cycling on productivity. Mechanisms 
are discussed by which nutrient supply affects primary pro- 
duction. It is concluded that plants often adjust their growth 
to the amounts of nutrients available. Poor sites, therefore, 
often have a low amount of photosynthesizing organs (low 
leaf area index). Lack of nutrients may also affect the effi- 
ciency of leaves and the redistribution of phytosynthelic 
products, and interfer with water regulation mechanisms. 
The need for further ecophysi<dogical studies is emphasiied. 



^L.(..y I lyi lied material 



C O. T AMM 



O o S Hallmyren. Wood Aihes 1918 (3.3 t/ha| 
• ' • S Hallmyfen. Wood Athes 1918, 1949 (3.3, 6.0t/ht| 
N Hallmyren. Wood Aihes 1926 (12.5 t/ha» 




0.0 1 \ \ i J I I I I I I I 

1949 50 51 52 T 962 63 64 65 66 67 68 

FIGURE 6 Nutriant concMitrttiont (p«rcMit dry MMight) in birch laam from tha ptott in Figiira B. 



Copyngliiuu r:ia;crial 



PLANT NUTRIENTS AS LIMITING FACTORS IN ECOSYSTEM DYNAMICS 



131 




Copyrighted material 



132 



COlTAMM 



FIGtmCS Hti^ttrawA f967- 
1969 plonad against foliage nitrogen 
concentration of ^iruc« fartilizad 
annually from 1967 omi«lfdkC» 
parinwnt E26 A SttinR. 



160r- 



ll 

•9 



100 - 



•o 



X 

O 



X 



X PO 

O PI 

• P2 



_J I I 

t.O ?.0 3.0 

Average Foliar Nitrogen Conttni, 1967-1968 



REFERENCES 

Artand. A 1 9S4, Die TruHpintkmiiitMfilat 4er Fflanien als Grond- 
tage tel der Eradtthiag optlnukr acker- und pflaRHnlMuUchcr 
Kalluimasuuhinen unler besonderer Bcrikkiilchtigpng iron 
PflanzcnaniJyscn. Plant analytb and fertttlzer probiems. CoHoque 
organise par I'l R n o sn.is I,i I'!c^^^^^;nL c tic [I I un;lci>^rdh dans 
Ic cadre du VIU'^ ( .int^rcs Inlornatmnal de Botaniquc. p. 35-47. 
Parii. 

BraK, H. 1972. The influence of potasnun on the Uanipintioa rale 
aad itomalai openioi In THtkmm tatimm aad Pimm mdvum. 
Phyiiol. Ifamt 36:3SO-2S7. 

Brix. H.. and L. F. EbdI. 1969. Effiwlt of niUof^n fertiHtatioa on 

growth, leaf area, attd phoioqnIliMil nie ill Dai|||a»ar. Foiat 

Science 15(2) 189-196. 
Bnx. H. 1971. liMccts of nitrogen fcrlilisation on photosynthesis 

and respiration in Oouglaa-rir. Forest Science 17(4):407-414. 
Brix. H. 1972. Nitrogm fcrtiiiation and water effecu on photoom- 

timit nd m|y WMMMilMNKid pnidiiction in DoB(ia^fli> 

CuMdlMi Joamal of Pomi Rcieatdi 2(4):467-478. 
Gore, A. J. P. 1972. A rield experiment, a small computer and model 

simulation, p. 309-325. In J. N. R. Jcffcrs (cd.) Mathematical 

models in ecology. Symp. 
llessetman. H. 1937. Om bumusiackets bcroende av bestindets 

llder och nmmaninaiQg i den nordiska granskogen av bllbinilk 

V iw AiliiwHyp och daai Imwkwtpt ihotent loiyngrim och 

dBvixt. Medd. St. SkogifSnolcianit 30:529^8. (Swediih with 

German summary.) 
Ingestad. T. 1 962. Macroelement nutrition of pine, spruce, and birch 

sccdimgs in nutrisnt aataHoBi. IMd. St t/tagkotiOh Imt. 

51(7);1-150. 

KeUcc, Th. 197 1. Der Kinnuss dcr Slickstoffernahrun^ auf den 
CwwKhaei der Fidlle. Al%. Font-u. J. -Zls. 142(4J:89-93. 
Hildirii. H. L., and IL P. Oiwdler. 1939. Hie •HntM iwtiMM 



and growth of cerlam deciduous trees of Northeastern United 
Slates. The Black Rock Forest. Bull. 11:1-94. 

Nielim. B. F. 1963. Plant ptodHctioo. tianipintlon ntki and nii> 
tiient fatkm aa influanecd by intctictiaiia belwacii water nnd 
niUviMi. HMiila R. VaC Asiic Oolt. CopnlHiBMi. 

CMflgton. I. D. I9ST. The vnbtfli mtter. oipaie evbenaad ni- 
trogen content>oftiwipadM|nnniiadoaiitHids.Nnr 
Pbytol. 56:1-11. 

Ovington. J. O. l9S8.TlMtodilunt potassium and phosphorus con- 
teau of tice ^eciaa gmwa in doae attnda. New Phy toL S7:273- 
2M. 

MelMfdi, B. N., and D. I. Bevege. 1 969. Critic^ fuller flonentn- 
ttom of nitrogen and ptioipiiorui a* a guide lo tiw BBiriiMt 
status of Araucariainid«lplailMdtoFlinM.nHMmlSoll 

31(2);328-336. 

Romell, L. -G., and C. Malmstrom. 1945. Hcnrik Hcsaelmans tall- 
fiedsforuk lien 1 922-42. Mcdd. St. skogafonolctanal 34(1 1): 
543-62S. (Swediiii widi EacH* HnBaiy.) 

Ttain, C O. I9S4. So— o t i ya tlona on the nutrient tnnMmi !■ 
a bog comnittnlty dominatod by Erkpborum Vaginanun L. 

Oikos 5(2) IR9-194 
Tamm, C. U. 1 968. An attempt to astcn tlie optimum nitrogen level 
in Norway ^nice nadat ikM oondilloii;. Sted. fat img. No. 
61:l-«7. 

Item, C Q. 1971. Mteaiy production and MiiKmr is a iprooe 
fHcat t m uif mm widi wMtoltod nutrient strna U SwedUi nP 
proieet). Sjrslnni amlyda bi nonheni oonif«Tou foratti-lBP 

Workshop Bull, from the Ecol. Res. Comm. 14 1 14-145. 
Whitehead, 1>, C. 1970. The rote of nitrogen in grassland productivity. 

Bull. 48. Commonwcaldl Blir. Pttt Hd FMd Ompi. Nwl*y. 

Berltihire, England. 
Zehetmayr, J. W. L. 1 960. Afforesution of upland htatln. BuU. of 

die Great Britain Foreatiy Canmiiiian. England. MS p. 



Copyrigliiuo r:ia:.chal 



MINERAL CYCLING 
IN TERRESTRIAL 
ECOSYSTEMS 



p. DUVIQNEAUD and S. DENAEYER-OE SMET 



INTRODUCTION 

In any optimistic or pessimistic perspectives we may have 
about the future of our planet, botany is rarely considered. 
Although plants are the abeohtle baae of flic atlmentation of 
animals and men. some people may ask themselves "Is Kotany 
still alive?" Recently, hpstein (1972) has pointed out a "blmd 
ipot** in biological sciences: the knowledge oflSne mecha- 
nisms involved in plant mineral nutrition. In our opinion, 
this gap results from insufficient knowledge of the relations 
to fwmiv between plants and the iidneral elcRients of their 
abiotic environment. 

For a long time the study of the plant-soil relations m 
natiue has been approached by muiy diadpUiiesbut with 
little interchange among them (botanists, geologists, apron- 
omists and foresters; epidemiologisu). Today, a better co- 
ordination enables us to gather tiiese inveadgalloas in a 
modern science, called hioge(Khemistry , frODI which beiin 
to emerge important principles and laws. 

One of the most important aspects of blogeochemistfy is 
the study of mineral cycling, because, as well as energy and 
water, some mineral elements (called nutrients ' biologically 
essential elements) are required in sufficient <iuantities for 
sustenance of the ecosystems and their components. Bio- 
geochemistry is of practical interest and application when 
some elements, essential or not, are artificially incorporated 
into the ecosystems by human activities and become tOKiC 
for living organisms (e.g.. S. Zn, Cd and Pb). On that 
viewpoint, biogeochemistry may contribute substantially 
to solving the problems resulting from the increasing poQu* 
tiOD of the envifonment 

133 



BIOGEOCHEMISTRY 

Most of the investigations perfoimed till now in biogeochem- 
istry have concerned only plant-soil relations, except for 
health related trace elements, such as Se (see p. ISO), and 
some other elements for which investigations on faod<hain 
relationships began about ten years ago. A general review of 
this important aspect of bio g sochem ls tiy may be found hi 
Hopps and Cannon (1972). 

Owing to their more spectacular character, abnormal soils 
(those affected by *1riQgMelMadcal anomaliM»** M«h as exp 
cess of salt, heavy metals or defirtenccs in P. Co^ Cb,etC.) 
and the corresponding vegetation have been much mon 
Studied than '^MMmal*** soils and vegetation. The study of 
soils unbalanced hy cvccs.'; or lack of an clement, which may 
cover wide areas, is the basis of very important practical ap- 
plications, such as the utilization of sea water for the irriga- 
tion of desert zones (Boyko. 1966). Data obtained from the 
study of abnormal soils nuy lead to generalization and con- 
tribute to tiie estahUsbment of a genetat theory of nUneial 
nutrition of plants hi nature. 

Indicators-Accumulatort-Concantrators 

Some plant species show by their presence particular diemi- 
cal sofl conditions. Exduiive or preferential, these *Hndica- 

tors "are generally adapted genetically to their substrate 
(physiological eootypes or distinctly differentiated species). 

* A loU any IM eoMldeied as oixmal wlien Its chcmlGal eompo^^ 
is not an •Minllal ilmiUag (telor for piaal Jevdopment. 



134 



p. DUVMNi AUD mi S. OiNAiViIMM WfllT 



Indicator species are often called ^ucUdists (selenophytes, 

cuprophyles, ^incophytcs, etc.)- In fact in a given region, 
every species is a specialist of a particular ecological site. 
Duvigncaud ( 1946, 1949), Diichaufour (1957), Blenbeig 
(1954, 1%6), and Schienker (1939. I960) led to a phyto- 
sociological or pcdological mapping for several regions of 
Europe. Much remains to be done in this field. 

Exception here has to be made for the weeds which 
colonize all typ<?s of tjistuihe.i ■^oils (roadsides, gravelly 
shores, mine spoil-heaps, gaidens, abandoned cultures), and 
which extend lo the Udllngi of abandoned Cu. Zn and Pb 
mines and to all kinds of pdlhited sites (even able to persist 
at high levels of ionizing radiation). I hesc species which con- 
stitute eco^tems in the most poOuted areas have been 
called gencralisis by Woodwell (1970). 

The mineral composition of plants depends on many fac- 
tors: concentration of the chemical elements in the sc^ 
pH. ion antagonism (for their influen e on the availability 
of nutrients for plants), soil moisture and temperature, root 
morphology (not yet weO Icnown), root cations exchange 

capacity (still discussed, .see Wacquant. 1^68, 1069. Hemp- 
lull, 1972), age of plants, organs (leaves, stems, fruits, roots 
difTer gsnsnlly in mfamai oompaiition) and g^tk con> 
stitutlon of the plant spedes. 

Selectiva Absorption and Acaimuiation of Chamieli 
Elements brf Plant Species 

The mineral composition of different plant species growing 
on the same aoH or sampled in their respective ecological 

optimum conditions may vary widely because of the selec- 
iivtiy of the absorption and accumulation of ions by plants 
species (Hohne, 1963; Omigneaud and Denaeyer, 1966. 
1968. lP70h; Hemphill. 1972). This phenomenon may be 
maslied by mtluence of the substrate (luxury or poverty con- 
flumptkm) and a detailed nomendatute has been proposed 
by Duvigneaud and Denaeyer (]^l70:i). The s.ime mitliors 
published recently (1973) a paper on the ecology of muieial 
mitfltion of plants fat nature. 

Plants may be divided intn ncnn .iiu1 rich Species on the 
basis of foliar analysis and with reference to standard plants 
of aveiage mbierd composition; among die latter, they are 
accumulai()rs of elements present in excess in the soil: 12 
to 16 percent Na in halophy tes (Denaeyer et al., 1968), 3 
to 7 peicent S in gypsophytes (Duvigneaud and Denaeyer, 
I968X >n(^ concentmton which absorb very high quantities 
of elements found in normal concentrations in the soil: 
800 ppm F in Camelia sinensis (Hemphill, 1972), 5,000 ppm 
in Vaccinium myriillus (Denaeyer-De Smet, 1966), 845 
ppm Co in /Vvs.w sylvaiica (Kubota and Allaway. 1971), 
10,(XX) ppm Se in Astragalus bisulcatus (Trelease and 
Trelease. 1939). 

Conceatialon can play a very important part in the evohi- 



tion of die ecosystems by acctmiulatbig, on the soil aurftce 

througli litter shedding and decomposition, elements which 
are dispersed in the soil or formed directly from bed roclc. 
If Ihew elements are little mobile, they form a highly en* 
riehed auperfkial layer and their chemical form may be 
modifled, e.g., mineral Se converted into organic Se by 
"TYans forma lors" plant species (see also p. 150). 

The mineral composition of animal species is little known. 
Edward; n al. ( 1970) and Reichle ( 1971) who Studied the 
content ot Na, Ca and K of 37 kinds of invertebrates in a 
tMNfendhm wood (Oak Ridte.Temiessee)liave Aown a 
very high specificity: lsnpod;i and Dipinpoda accumulate 
Ca (1U3 mg to 546 mg/g ash free dry matter; Lepidoptera ac- 
cumulate K (50 mg/g) and, to a lesser extent, Na (9.2 mg). 
Data concerning the mineral composition of ! umhncids and 
Basidiomycetes are given in Duvigneaud et al. (1971 ). liarth- 
worms accoroidate mainly N (8 J percent dry wei^t), S 

(0.6 percent dry weight) and P (0 4-0 8 pLrccnl dry weight). 
The carpophores of Basidiomyceta are K accumulators (2-8 
percent K dry weight) but do not absorb much Ca (0.06- 
0.15 percent dry wciglit) probably not essential for fungi. 

The soU-i>lant-animal relations have been recently over- 
viewed by Homth (1972) for the most Important health 
related trace elements. He emphasized the importance of 
accumulator plants wiiich may intoxicate grazing cattle: ex- 
cess of Mo after intensne N fisrtfiization, Se occurring in 
nathfe soils, or Cd emmissions oijgjnating from Zn industry. 
Because plants are the main source of the mineral elements 
required by animals and man, plants are also involved in 
health diseases because of the deficiency of some elements, 
e.g., Cu (deficient in very Lii-id-sandy soils, in peat and muck 
soils, in highly N-tertilued soils, etc, see also p. 151). Horvath 
(1972) emphasized also the role played by the genetic con- 
stitution of animals in their resistance to excesses or deficien- 
cies of nutrients. The competition among mineral elements 
bt lelatioQ to digestive absorption by aoimaU has been re- 
viewed by Davit (1972). 

MINERAL CYCLING IN TERRESTRIAL ECOSYSTEMS 

One of the great contributions of biogeochemistry is the 
study of die mnieral cycling that contributes to our under- 
standing of the functioning of the ecosystems. Following 
the definitions given by Ovington (1968), mineral cycling 
involves the bhlt^al eyde which corresponds to the cir- 
culation of elements within ecosystems (mainly between the 
phytocenosis and soil) and the geochemical cycle which 
means the flux of elements from the abiotic environment 
into and out of ecosystems. Mineral cycling includes both 
essential elements (macro- and micronutrients) as well as 
ballast elements ( Al, Si) and toxic elements occurring in 
natwe (Se»Cu. etc.) or ioeotporated artificially in the eco- 
aysteois as a result of human activities Cd, Hg, etc.). 



Copyrigliiuo r:ia:.chal 



MINERAL CYCLING IN TERRESTRIAL ECOSYSTEMS 



135 



BIOLOGICAL CYCLES 

In Western Europe, the concept proposed by Albert (in 
Detukr. 1930) for forest eco^stems is often followed: 

abmptlon - le^iion * lestitutioii. 

Retention means the quantity of elements retained in the 
mnual increment of perennial organs. In forest ecosystems 
retention is very high and leads into a stocking ("mineralo- 
mass" sensu Duvigneaud, 1968) of elements in stems, 
bmiehea and roots of the trees. Sometimes a concentration 
may occur (C:\COi in the stems of Otlorophaea excelsu Al 
in the stems ol different tropical species). Restitution to the 
mD of • part of the ibwrbed dementi is csnied out by ihed> 



ding and decomposition of litter (dead leaves, fiuits, dead 
wood, etc.) and by iiin leaching of the phytocenodt (for 

more details see Carlisle efa/.. 1967; Denacyer, 1969; 
Nihigaid, 1972). When litter decomposes slowly, restitution 
may lead to an accumulation of elements adsort>ed or 
chdated on the humus colloids. Restitution of nutrienti 
may also occur by living roots (desorption, exosnosis, aecf^ 
tlon) especially at the end of vegetation period. These 
problems have been intensively studied by several Soviet 
authors (Boriskina.Titova, Pogrebniyak. 1955). 

Figures 1-3 show different methods for representation 
of the biological cycle following the classic concept of 
DciijJlu ( lOlO) Fipiirc 4 ri'flccts the concepts of Siwiet 
authors. I hey uliii/e the notion of "carrying capacity of 
the biological ciraolstion** which cone^iondt to the qaanH- 



ANNUAL MINERAL CYCLING OF K 





Boln 



DISTRIBUTION OF K 

Crop 




Botai 








Hartweaou* 








LImr -4 Animals 



nOUREI AiNMMlMoloelcilcvelea* Klna47-vi«^ 



Copyrighteu iiiaiorial 



136 



p. OUVIQNeAUD Mi «. OINACVCR-OI «MIT 




K Ca M9 N 8 P 



■wti In > 11 7 rw u M Bil l I w nl form tOm w> lB'Pa> »> WMiw) to IiIi I bw 
B»tiwwwid<>nib«.«idliilli«>iri«ii W pifti«f iMI m l Mt twi i liyir. 

B*l*tt»d by dMd Mrial parts of lh« hwtMMOut lay«r (lii^ttv ttipptod), by tra* and tfirub liner (modaratalv ttippMI, 
by throughfall and ttamllow (hl^ly ttipplad). Absorbed' rataincd * ralaatad. Imported by incidant rainfall (valuat 
o( K arkd Ca at Faraga; Mg. N artd S at a naarby ttta (Oourt>at, National Intt tute for Epidamiology and Public Hsaltbl. 
Exported by drMnaga wrattr (mtrapolMad, aftar Likam n 19711. Italic*: Minaral contant of gnan laawaa (July). 



RQURE2 



lies of elements absorbed by the net primary productivity 
(NPP = ligneous inctement plus green leaves) and ihe nuiion 
of "true increment" (NPF minus total annual litterfall). 
Mineral cycling is thus esiimaied as fi)llows; Absorption in 
NPP (measured) minus Kestitutiun by toul litter (measured) 
- Retention in true increment (calculated). 

Due to the lack of sufTkient data, Soviet authors do not 
i;ike ui ^account restitution by rainieaching of the canopy and 
sicmiluw. Following the Soviet concept, in a climax forest 



the values obtained for retention may be negative if the 
quantity of dead wood is larger than the ligneous increment 
For meadow ecoiystems Soviet authors Amplify the bio- 
logical cycle by considering that the elements released by 
aerial dead parts correspond to the quantities of elements 
absorbed annually by the living parts. (However, the knowl- 
edge of the restitution of elements by dead roots may be neci^ 
sary because of the high productivity of these organs.) 
Scandinavian authors also estimate aiuual absorption throu^ 



Copyrighted material 



MINERAL CYCLING IN TERRESTRIAL ECOSVSTBM8 



137 



kg/ha/yr 
200 



180 



160 



140 



FI0IME3 

I at tfw mimhI Hota^ort •! 
) In Nvanl tenat •MirMHM • 
ftmtmn Europ*. 

A. Qimrcttum mix turn at Virallai, 
Batghim (Ouvignaaud and 0«na«y*r. 

1970b|, productivity " 14.6 t/ha/yr; 

B. QiMfeatum ilieit at MompaUiar, 

C. F«9»tum nudum at M tw art, 

Belgium IDenaeyer and Duvignaaud, 
1972), productivity - 14,8 t/h«/yr; 

D. PK*etum at Mirwart. Batgium 
l/Mtf). p«<odMcinitir - 14A t/lM/yr. 

lin 



120 
100 
80 

60 

40 
20 



nnaan (aneapt in B, aarad onlyl; i 

liran r iploiisnd by traa litlar; obliqua tina 
r«i«aied liy d«ad parts of harbacaoui 
layar; itipplad: lalaaiaritoy " ' 

and atantflaw* 



kg/ha/yr 
IX, 

80. 

60. 

AO 

20 

0 



i 



it to 



B 



K Ca Mg N S P 



K Ca Hg N 



1. 1, 1 



n 



rr 



K Ca Hg N S P 



K Ca Mg N S P 



Copyrighted material 



138 



p. OUVIGNEAUO and S. OENAEYER4>E SMET 



FIGURE 4 Bioinaa, productivity, 
and annual biological cycla of nu- 
trianti in a 222-yaar-old oak f orast 
{Querceto Aegopodietum "dubrava") 
Voronasz, U.S.S.R. (Rodin and B«x- 
ilavieh, 1967). Obliqua linat: gra«n 
parti; Mack: aatial parannial parts; 
opan: roots; braca: trua incrafnant 
of aarial and tubtarranaan parts. 
A ~ bioman; B = minaralomias; 
C " annual abcorption in nat primary 
productivity Igraan laava* *■ wood 
arMi bark incramant); O ■ ralaaiad by 
traa litter; E = ratairMd in trua incra- 
mant (E - C - Dl. 




800 



NPP ("carrying capacity") but do not separate the mineral 
content of green leaves; consequently there is no possibility 
10 estimate the annual retention in wood and bark increment 
only. On the other hand, they calculate the mineral content 
in what they call ■ ' B (wood and bark NPP minus dead wood), 
which is very nearly the value of retention iensu Ovington, 
because in the ecosystems studied by these authors dead 
wood is not very important (+10 percent of the NPP biomass). 
It is thus possible to make comparison between values ob- 
tained following European and Soviet-Scandinavian concepts 
(Table 1). 



The restitution of mineral nutrients is closely related to 
the turnover of organic matter which involves a complex 
range of processes from which the main classical stages are 
as follows: 

- litterfall and accumulation 

- litter breakdown and transfer by pedofauna 

- chemical decomposition of the litter, immobilization 
or remineralization by soil microflora 

- humification and dchumification 

- reabsorption by green plants 



MINERAL CYCLING IN TERRESTRIAL ECOSYSTEMS 



139 



TABLE 1 Mineral Cyding in a Beech Forest 90 Yean 0(d and in an Adjacent Spruca Forast 
M Ywn OM; «t Ktnari«mtf tttrndank afHr NMoh4 119721. Compwiwn BMwmii Anmirii 
Atoafp«iM CilarialiM FoHowIni Ttm DNfMwn Coi^^ 



kl/ha/yr 





K 


Ca 


Ki 


N 


S 


F 


achFoieil 














Relalmd In item and branchet inc cement 


164 


MM 


M 


•3 


2jS 


is 


(minui dead wood) (10.1 iflufyt) 














Returned by 














• littcifall (5.7 t,i1ij/yr) 


14.4 


31.7 


4.3 


69 


6.4 


5.0 


• through fall + ^temilow 


11.2 


6.6 


2.5 


1 


10.6" 


0.1 


Absorbed 














a) aeiuu Ovinfton (letained '•■ teleaaed) 


42.2 


63.1 


10.2 


1S2 


19.S 


8.5 


b) MonltodiiiUtaavbediaaeiprt- 


43.1 


49.S 


10.» 


204 


lA 


10.9 


maiy piadnctivtDr) (IS.1 t/Wyr) 














fucePoretl 














ReKincd in ■.^cm jnJ hranchcs increment 




124 


1.9 


14 


19 


1.C 


(minus dead *ood)( 10.1 t/ha/yr) 














Returned by 














e litterfaU (S.6 i/ha/yr) 


10.7 


19.8 


3.1 


58 


5.4 


4.8 


• ihromhfidl and stemOow 


2S.2 


13.9 


S.2 


1« 


4CJ 


04 
















a) aamu Ovingten (lelained * lehaiad) 


44.4 


45.7 


10^2 


88 


S44 


<.8 


b> wnau Rodin (absorbed in net pii* 




12.7 


4.S 


(7 


6.0 


9.1 



mary productivity) (13.8 t/ha/yr) 



*40.8 kf/ha/yr beneath Fagctum Canopy In Soiling (Weal Germany) (Ulrtch etoL, 1971). 



BIOLOGICAL CYCLES OF MACRONUTRIENTS IN 

DIFFERENT ECOSYSTEMS 

in Western Hurope a long time after Albert (see Dengler, 
1930), Ovington and M.idgwick (1959) again brought into 
vogue the study of biological cycles in forest ecosystems. In 
the USSR, Rodin and his co-workers considered the problem 
on a world scale. A first synthesis of mineral cycling in forest 
ecosystems was attempted by Duvigneiud and Denaeyer in 
Pfv) An intensive rcscarcli prot-'ram on !his suhicct was ini- 
tiated in Belgium (Virelles) and later due to the IBP similar 
ptolecti developed in dlflerent countries of Europe (West 
Germany, Soiling; Sweden, Konj::;luniJ Denmark, Hestchaven; 
Great Brittan, Meathop; France, Montpellier; Chechoslovakia, 
BA; Belgliun, Miiwirt) ai weO ai on a veiy laige xile in 
USSR, USA and Japan Tlic main results of these investiga- 
tions are summarized in Duvigneaud (1971) and Duvigneaud 
efaf.(I97l>. 

In a given ecosystem the hidlupical cvcle fc^Ildws the 
curve of productivity; for example, in temperate forests, the 
tniximiHn vahie is reached betwsen 2S and 40yeafa (Oving- 
Ion and Madgwick, [''"i''. Rcme/ov, 1963). Therefore, com- 
parisons between different eco^stems are most valuable 
when examining ecosystems which have leached theii climax 
or luve the same biomass and belong to a given biome 
(foietts, grasslands, tuDdias, etc.). 



A comparistni made by Tsutsumi (1971) between different 
eco^stems having nearly the same biomass (±100 t/ha) 
from the subarctic AMa forast to die tropical forest of 
Thailand has shown that mineralomasses dapoid on both 
the fotest type and on bedrock cheoiical oomporition. 

Comparison of Mineral Cycling 

A simple graphic method (Figure S) allow s a general com- 
parison of annul] abaorption, whidi gives a good idea of 
mineral cycling in ecosystems This method is based on a 
polygonal representation: six axes, starting from a 0 point, 
leavtag between them an angle of 60* and graduated hi 

kg/ha/yr with each axis corrcspondini: to a macronutricnt. 

Connecting the six points corresponding to the annual absorp- 
tion of each of the dx aaaeronatiknto yieldi a p«dy|onal 
figure whose form and area are chatacterMc of the eco- 
systems. 

For die Temperate Deddoous Forest bkrnie, tfie turfiwe 

of the polygons corresponding to oakwood ecu a stLtiis 
((Juercemm) ismuch larger than the surface of the polygons 
for beediwood ecocystetns (Fagetimy, tfils means that ttie 
total quantities of absorbed nutrients are higher in the 
former than in the latter. The form of the polygon depends 



140 



p. OUVIONE AUD and S. DENAEVeR4>E MieT 



on the chemical plant/soil relation. Annual Ca absorption 
is more important and K absorption is lower in caicareout 
ecosystems fFij-ure 5h) ( K T.i iintLipnnism). On the other 
hand, Ca absorption is reUuceil on very poor soils (Figure 
5d); Mg abtorption Ithigli on magnesiferous soils (Figure 
5c); N ab<;orption is high when mineializacion conditions 
are very favorable (Figure Si). 

In tiie Temperate Evergreen blome, ecosystems seem to 
be chaiacteri/ed h\ i lnwer annual absorption, especially at 
the N level (in tlic two considered ecosystems, Ca absorp- 
tion is higit because of luxury consumption on calcareous 
soil) 

In the Equatorial Forest biome, the annual absorption is 
much higher (ranging about several hundreds of kg/ha) than 

in any oilier ecosystem. Ttiis is mainly heuaiise <i!" the very 
high productivity (20 t/lia/year), important rainlcaching, and 
ttie fact fhat there are aevml Utterfidls per year. 

In the Coniferous Forest biome, the absorption of maercv 
nutrients is always low, especially in pineforest ecosystems 
(Pinetum). However, there seems to be an exception for S 
in a spruce forest of Sweden (Figure 5,1); the very high ab* 
sorption of this element results from an abnormal rcstitutioa 
by rainfall as a consequence ol atmospheric pollution. 

In the 'nmdn biome, aimual absorption varies widely: 
nearly the same as in Coniferous forest in the Vacdnbon 
tundra, but extremely reduced in the spotted (not represented 
in Figure S, becauae it diouU be onily a very litUe pobit). 

In the same way, the annual absorption in the "Steppe" 
biome depends on the kind of the considered ecosystem: 
annual absorption in a graariand ecosystem is oomparable to 

ahi^ prciductive deciduous forest, but is much more re- 
duced in semidesexttc Artemisia steppes and in salt steppes. 
In the lattet eco^stems, tfie veiy anall area of tfie polygons 
does not ghW a real idea of mineral cycling hccausc- uthcr 
elements (mainly Na and CI) become much more important 
than the true macronotrients. 

For cultivated ecosystems, the areas of polygons may 
vary widely following crop nature and reflect very well the 
different degrees of mitrient consumption; but, they are all 
characterized by a general more elongated form, resulting 
from K domination and the P high absoifrtkni. 

BIOLOGICAL CYCLES OF MICRONUTRIENTS 

Until recently, biogeochemical cycles of only Mn, Fe and 
aomeiimes Al wtn studied (Klausing. 1956; Ovington and 
Madgwick, 1959. Rodin and Bazilevich, 1967; KoUi and 
Reintam, 1970; Ulnche/a/., 1971 ; Nihigaxd. 1972). Today 
owbig to the speetrophotometric analyrit by atomic abaorp* 
tion, investigations have been extended to other micro- 
nutrienu. The fust results obtained concern however more 
the tadhiduals (Young and Gufan. 1966; Nilsson, 1972) 
than the ecosystems. Research programs concerning the dl^ 
tiibution and the biological cycle of micronuuienu in a 



beach and adjacent spruce forest are in progress in Sweden 
(IBP program at Kon^alund), in Denmark (Hestehaven IBP 

program) and in Belgium in the sariK forest types (IBP pro- 
gram at Mirwart). Figures 6A and 6B show the first results. 

INPUT-OUTPUT BUDGET and BIOGEOCHEMICAL 
CYCLES 

Input and OmiMit off Nu trienis 

In terrestrial ecosystems, input of nutrients occun by: 

-precipitation and diy fallout. Under certain circumstances 
(aemidesert regions, slightly fixed soils), wind-blown dust 

may constitute an important input of iTiineral elements. In 
Guinea, for example, the rainforest is continuously enriched 
ia nuliients by dust removed from Sahara by a very strong 
North wind, fai ecosystems submitted to pollutant emissions 
as a consequence of human activities (industrial plants, road- 
skies, etc.), rainfall plays an important part, bringing to the 
saO many kinds of pollutants (H2S04. Pb, etc.). Vegetation 
may play a bcncricial role, acting as a screen and trapping 
many airborne particles (forest ecosystems are especially ef- 
ficient). 

- microbial atmospheric N fixation (average of 25 kg/ha/ 
yr by Azolobacier or Qostridium and 1 50-160 kg/ha/yr by 
RMxoldum in legumlnaceous cultures). 

- rock weathering by deep roots (mainly tree roots) 
whidi absorb the most soluble elements and restitution of 
tfiaae dements by litterfaO (Hartmann's law). 

- microbial action on the soil skeleton and on bedrock; 
this action is performed directly by contact or indirectly by 
ftxmation of CO3 . oxidizing humic adds or aUcaline coro- 
poundi(Wilkanp, 1971). 

Output of nutrients is carried out by human activitiea 
diarvesting, forest exploitation) (Rennie, 1955), soO water 
nmoff (dissolved and particulate elements). The estimation 
of output rate is diffictdt and needs complicated and ex- 
pensive techniquaa,(e,g.^ tension plate lysimeters, evapo- 
transpiration measuRment by tritiated water, smaU water* 
shed systems). 

The input-output budget depends above all on the 
hydrologiL.il yclc Geochemical fluxes and biological 
cycles complete themselves by lateral exchaitges between 
adyacent eooiystenna, aafor example, forest and atieam eoo- 
lystems; research projects in this area have been initiated 
in the USA (Curlin, 1970) and in Belgium (IBP program at 
Mifwart), 

Comparison «f lapMOiitput Bttdgata 

Comparison of the results obtained from several studies 
(Table 2) shows that nutrient loss from ecosystems generally 



CYCLING IN TERRESTRIAL ECOSYSTEMS 



141 



nOUMS QiVhical raprMMitation and 
iiompirlion o( llw ■nnual biolagieal cycto 
of nutriani alwfwnli in t 



■Mai 



nt: 7.9 t/ha/yr; Itttar: 6.8 t/ha/yr. 
b. Ou^rcetum mixtum, 3S-7S yMn old 
•t Virall«i (High Mgium), darV brown 
randiinoMic wi Ca Hiura«ad. Aariil incra- 
: tatffM/yr: littw: 6 t/Wyr. 




EvwgrMn fbrwts 



l» 1% iUriil Iworwim rt i BA 1/ttatfn 
mmr. M t/ha/yr. 

d. QiMfC0tum. 135 yain old it 
iHMi Batgiuml, paaudoglay podid mur 
poor in axchangaabto baaaa. Aarial li 
■Mt: 3.1 t/lM/Vr; lltMr: 73 t/lM/yr. 



Crops 



». Wll. 

a. Qu*rc*to t»gop (xfiostxarlcotum. 
222 yaare old In th« provinct of Voiuiiaii 
IU.S.S.R.). Aarial incramant: 2.5 l/ta/yr: 
linar: S.6 t/ha/yr (■ 
BmNmWi. ItSTI. 

LOmimih 
at Ma m palllw U m d H a w —i Franeal. on 
ndaoN. AmM tneiMMM: 23 VhWVr Ipro- 
I lawlti): litlw: 6 to 9 t/ha/yr (only 
a). Tha S eyela hai not baan attablithad 
IsHar Rapp and Loauint, 1971). 

g. Motho/agttHn about 100 yam oM, at 




.Lltawi 

6 t/ha/yr (tfiir MRtor. 1««3t. 

h. Fagetum, 130 yaars old, at Mirwart 
(High Balgium). acid limono-ttony brown 
•oil, poor in axdiangaabia baaaa. Aarial incra- 
mmt: 6^2 t/ha/yr; Uttar. U l/ha/yr (aftav 
Otwfr Dmlpnnl, tWH. 

I. A«MMib MvHitaM. at KMt*M> 
NMflwd,1l9l|. 

i. Oaiaa omlMphyta forast, 50 yaan old (aaeondary foraati at Ghana. AaiW 
not baan attaMWiad. (Aftar Graanland and Kowal. 1950: Nya, 1961). 

k. Piceetum, 58 yaan old, at Mirwarl {High Balgium) on acid III 
t/ha/yr; littar: 2.7 t/ha/yr (attar Danaayar and OuvignMud. 19721, 

L Moaaiurn, 5S yam aMIi al KansriimlltaMiMl, a* add hi« 
Nllilpii|,H7ai. 

ai. flaMum, awan aaNaa ahtalai d for JWfowwt f a i a a l i In Oowwawy mOA). 
19iy>. Tha t ayda hn wot baan ttadia d . 

n. Tundra «wlth Vaeeinium myrtiltus (USSRK Aarial productivity: 2.2 t/ha/yr (aflor ChapuHWk It'll, 
o. Maadow ftappa with Grammtceous tp. ar>d Filipen<tul*IO\wnvnm (occidental Sibaria); HMr: 103 tAtaAff. 
p. Arid itappa with CnmmacaoM ip. and Armnitia (plaina of USSR!; littar: 8.7 t/ha/yr. 
q. Stappa on Solaaali at KlMulMM <U11B>; aawMil IHUrt S3 tflwrfyr. latpi, 
li, 1988.) 



113 l/ha/Vr: IHMr: t/Mfw laflw 
213 Mafyf; Ntlw: 21.7 tMnrfyr. Tha S ayda hM 
HM. AmW iMianiiiili 103 
11,1 lAn^r, MtiHs 03 lAafV' Mlw 
• Htmhr.mim Mlfti^lafHr B iiadd, 



Cc| , , od material 



142 



p. DUVIGNEAUO and S. OENAEYEROE SMET 



(A» 



FIGURE 6 Annual mliMral cycUng of 
Mvaral micranutriwili In ■ i3 0 yM»t M 
ifonM(A|aMifaiM4 

•HwplOTtMlanlBMn 

wart pro^t. Bilgium); oMiqua linaa ■ 
ratairwd in incramant;hariioiital linaa* 

rwloa-w.'rf by littar;) 
by ratn4«aehln9. 




Mn Ft Zn Cu Pb 



Btaniais 368 t/ha 
ProdUCtMty 11.6 t/ha/yr 



(B) 




Biomaas 232 i/m 
PntMVMtf U4 t/lM/yr 



Mn H 



Copyrighted material 



MmeilAL evetlMO in TCmiEBTItlAL BaWVSKMi 



143 



TABLE 2 Comparison BttwMti the GaodMinicai Cycte of 
SiwiMl CiMniinI EliMwits in DiffiwM TypM of Fovnt 
EoofyiMni 



fcg/ln/yr 

Net Gain 







Input 


Output 


or Loss 


K 




Ooweela (USAr 


3.16 


5.17 




2.02 




Wtlkn Bnncta (USA)* 


4 8 


S.6 




0.8 




Hubbard Btook (VS\f 


1.4 


1.5 




0.1 




Btookhaven (USAI^ 


2.4 


3.3 




0.9 




CMar River WSAf 


0.8 


1.0 




0.2 




Solliiig(WG)/ 


2.0 


1.6 


♦ 


a4 


Gi 


CowMta (USAr 




6.92 




a76 




Wtlker Brtndi (USA)* 

Hubbard Brook (USAr 




138.4 


-105.8 




2.6 


10.6 


- 


8.0 




Brookhjven (USaW 


3.3 


8.0 


- 


4.7 




Ccd.i: K IV. r (USAy' 


2.8 


4.5 


- 


1.7 




SoUins (WG)/^ 


12.4 


14.1 


- 


1.7 


Ml 


Coweetj (USAr 


1.26 


3.0 


- 


1.82 




Watker Branch (USA)' 


3,2 


69.6 




66.4 




HublMnl Braok (USA]r 


0.7 


2.5 




l.« 




Brookhavcn (USA]^ 


2.1 


6.1 




4.0 




Soiling (WG)/ 


1.8 


2.4 




0.6 


N 


Hubbard Hn i K a SA) 


5,6 


2.2 


+ 


3.4 




Cedar River (l.'SA)'' 


1 . 1 


0.6 


+ 


0.5 




SoDinft (WC)/ 


23.9 


6.2 


♦ 


17.7 


S 


Hnbbanl Brook (USA/ 


12.8 


16.2 




3.4 




SoOlagdlCH 




24.7 


♦ 


0.1 


• 

r 


Uoar Kiver \ \J9Ar 


If 


VJU 




ao2 




Sotting (WG)/ 


0.48 


0.01 




a47 




Cowccia (USAf 


5.4 


9.74 




4.3 




Walker Branch (USA)* 


9.2 


5.3 


+ 


3.9 




Hubbard Brook (USA)^ 


1.5 


6.1 




4.6 




BcooUitven(USA)^ 


17 


19.4 




2.4 




Soliili(WG)/ 


7J 


SJ 




1.5 


a 


Hubbard Brook (USA)f 


SJi 


4.9 


♦ 


OJ 




Sotting (WG)/ 


I7J 


17.1 




0 


M 


Hubbuid Brook (1I8A]F 




1.8 




t.8 




Sotting (WG)/ 


3.1 


10.3 




7.2 


Fe 


Soiling (WG)/ 


1.2 


0.07 


♦ 


1.13 


Mn 


SoUinf (WG)/ 


0.22 


4.3 




4.1 


SIOi 


Hubbard Brook (VSAf 




3S.I 




35.1 



'C'uwecta, North C arolina, oak'hick<ir> (Quercus, Carya) mature 
foKst, precambrian gneiu (including granite, diurile, mica gneisa and 
nka BChbt) (Johnson and Swank, 1973) (small watersheds method). 
N^alker Branch, aaalam Tanaaaaaa, oak-liickofjr {QiMncut, Carya} 
nature forcti. dolomiia (Miaaon md SunMh^ 1973) (laull wulat^ 
liMda method). 

'Hubtord Brook, New Hampshire, mUad fiMest {Acer saccharum, 
fiagu* grandifloia, itofyia aUagkmilaittt, Hem mbtia), b«dr«Kk: 
quartz. piagioetaia.biatlta (UhanaM «L. l97l)(aaMll waimhadi 

ncthod). 

''Brookhaven. Long Island, N.Y., New HampalUre, late succe&!>i<Mial 
oakpina fofwl (Mhu liglda. QiMreuM Ma, Q. e o eei it t a, Q. MliiHm), 
(Ijrriiwtric MotlMd). gtacW owtwask aaatda (Womiwall aad Whlttakw, 
1968). 

'Cedaf Khwt mutch tm, mMm W i *lwn oi i , 36-y4w-aM Douftaa 
flr (fttudottuga mtiuitMO pliatatiM a* a (ladal outwotk aoO 
A|«taMtiicmaHNl)(Qoi««tfll, l*«7>. 
/Sodtag, near GMIiniaa (Waatetn Omnumf}, l3S<]r«w«M baach 
t^^tfhttlet} romt, badroek: Irinife nndMOM (INiMi tttl, 
197 1} dyilMtfie OMlfeodK 



exceeds rainfall input except for N; for other elements, it Is 

not yet possible lo give general rules because of insufficient 
daU. Table 2 also shows that loss or gain of an element is 
always low, except for eeoiyitems established on rich and 
relatively soluble bedrock (dolomite at Walker Branch) i r 
for ecosystems submitted to emission of pollutants (especially 
N oxides and S coropounda). 

A comparison between different ecosystems of the same 
little watersheds system and established on the same bedrock 
(Table 3) show that the cations input-output budget may 
vaiy widely following the type of phytocenosis; it seems 
not yet possible to give general condusiomt on this subject. 

BIOGEOCHEMICAL CYCLES 

Cole el al. (1967) were the lust to eslabli&ti the relation be- 
tween biological cycles and geochemlcsl fluxes. They found 
(Figure 7) in a second growth PseiiJotsuga Menziesii forest n 
low output of N, P, K and Ca but a very high accumulation 
rate of these etements in die ecoaysiem; they calculated that 

such an actumulation would result in n depletion df s<ii! 
nutrients after 12 years for K (exchangeable). 64 years for 
Ci (exchangeable), 125 yean for N (total) and 582 yean 

for P (total). 

Recently, Ulrich et d/L .(1971) calculated wtiat they call 
the '*blo8eocbeniical flux" for a ISO^ear'old beachwood 
(IBP SoUiiig project) corresponding to the differ enee be- 



TABLE 3 Average Annual Cation Budgets for One 
UndisturtMd and Three Manipulated Watersheds during 
Two Water Years (June-May, 1869-71. Coweeta. U.S.A.) 
Mftar Jehmon and twanh, 1973) 



Fareit Type 





PieM-t»Pomi 


It 


White 


Mature 






Coppice 


Pine 


Hvdwood 


Input 


3.02 


3.25 


3.32 


3.16 


Output 


5.98 


4.62 


3.56 


5.17 


Net low 










oj[^aln 


- 2.96 


-1J« 


-0.24 


-i02 


Input 


5.73 


S.7« 


641 


6.16 


Output 


10.40 


S.01 


4.10 


6.92 


Net tou 










or gain 
Mg*^ 


- 4.68 


♦0.75 


+ ? -1 ? 


-0.76 


Input 


1.20 


1J4 


1.34 


1.2« 


Output 


6.2S 


2M 


149 


3.09 


Net loss 










or gain 


- S.06 


-1.34 


-0.35 


-1.82 


Na* 










Input 


5.11 


540 


5.70 


5.40 


Output 


IO.M 


<.S2 


«.<» 


9.74 


Net loss 










or gain 


- 5.75 


-M2 


-0.36 


-4.34 



Copyrighted material 



144 



p. OUVIGNEAUO and S. DENAEYER-OE SMET 



. I 

»m 'mm 1 



not Hn» 



NITROGEN 



tapMivd by ram 




Fmti rips' 10 k«/k«/ft 



utdiM f.«. POTASSIUM 




LhcSm horn 

FOTM* rio» I'lkl/lM/lI 



CALCIUM 



PiQURt7 



•yito of M, P. K, MidCa III • 



tween "soil input" (= nutrient input by rainfall and litMf- 
ftll)llld '"Wfl output" (« nutrient losses by percolation 
>valcr, measured 1 m beneath the soil surface) It is interest- 
ing to point out that the values obtained in ihis way are 
OMily the ame u Ihow obtuned for a very siinilir foieit 
ecosystem in Belgium (IBP Mlrwart project ) but by a quite 
different method (direct measurement of annual nutrient 
ratention and mtUntioii). 

The intensity of the biological cycle depends obviously on 
the rate of absorption and restitution of elements. In eco- 



systems established on normal soils absorption depends on 
primary productivity (= biomass). We know alio tfiat it may 

depend (at least in forests) on the rate of root mycorrhira- 
tion; the root-microbe association may result m 3.5 lunes 
gnatsr uptalw of P, 75 percent nMMe K lod SS peioent mora 
N by trees (Bjorkman, 1970). The greatest effect of mycor- 
rhizae on the rate of mineral cycling may be found in the 
dinott doaed cyck of minerals from litter to micronora 
(mdotra|iliic mycorrhizae) to tree roots in equatorial forests 
(direct mineral cycling: Went and SUric. 1968); the same 
phenomenon appears to happen in the modem flora of tonptr- 

atc f-'uropean forests. RcsliUjtion depends mainly on the 
turnover rate and for some nutrients (especially for K) on 



Copyriyliicu iiiaicr 



MINERAL CYCLING IN TERRESTRIAL ECOSYSTEMS 



145 



the imporUnce of pfecipitation (canopy leaching and stem- 
flow). 

It woud not be possiblf to review hero the very lurge 
niunber of pubUcatiuns on the action of the pedofauna and 
the pedoflora on fhe rapidity of decompoiitioa of Utter, 
which is much higficr on mull soil (high density of lumbrics 
and centipedes) than on moder or mor soiL Nutrients are 
not completely liberated by soil-orBanitnu before their 
metabolism is depressed due to dietary impoverishment. Di» 
appetnnce of the basic hydrocarbon matrix leads to pro- 
gpHrivt N and P enrichment, with the C/N ratio decreasing 
during deooropoaition. At the same time excess nutrients are 
liberated and progressive, and buffered rcmineralization oc- 
curs. It is thus conceivable that the rate of recycUng may be 
measured by the cellulolitic activity of microoigniams 
(Witkamp, 1 97 1 ) and in fact depends on the turnover of 
organic matter. 

The litter ■* pedofauna ^ mieronon -^toA'*^ root path- 
way is promoted by high temperature and precipitations 
(Wititamp and Vanderdrift, 1961) (eg., the very high rate of 
mineral eyding in eqmtoriai forests). However, before com- 
plete remineralization of nutrietits occurs, nutrients become 
immobilized in the soil organisms, especially in microflora. 
Such immobilizatian is very high and may lead to concentra* 
tion, e.g., bacteria' ciMitcnt IS percent N (f'/N between 4.5 
and 6.5), fungal content 1.5 to 10 percent N (C/N between 
8.5 and 13). Bacteria may also have a luxury consumption 
of Ca and K. Soil microorganisms act as a "biobuffer" for P. 
preventing abiotic and hardly reversible fixation of this ele- 
ment. 

Nutrient immobilization may lead to a momentary defi- 
ciency of some nutrients (e .g.. He and P) in the phytoceno- 
sis. The N cycle is much more intensive in tropical regions be- 
cause N uptake and rate of turnover are higher. On the Otlwr 
hand, the tropical N cycle is based on N03~ uptake, whereas 
in boreal regions it is mainly based on NH4 * uptake ( Ellen- 
berg. 1971 ). The intensity of the biological cycle may be 
estimated in a simple manner (Rodin and Ba/ilevich. 1967) 
by determination of the decomposition rate ui later, 

L_ (L = total litter accumulated on lOil surface, 
FL FL = fresh annual litter fall). 

Table 4 gives some data obtained by these authors and 
shows that the intensity of the biological cycle decreases 
with Increasing latitude. Using ^steiD analysis, Jordan and 
Kline (1972) coine to the same conchjsion. Some authors 
(Manil eial., 1963) apply the more complicated "Jenny" 
coefficient for the mfaient cycle rate. 

Stability wid Evohilioii of tfw Oydea 

Jordan and Kline (1 972) defhw the relative stjH.HiA of an 
ecosystem by the time required to recover the initial state 



TABLE 4 Intensity of Mineral Cycling in Some Woodland 





1 lArar nodm MM 


iBHii«ich,iae7t 






L 






SolUtlar(L) 










Fail 


f\T*m 


^jiiiainuB 

fONSi 


80 


aO 




lana 


30 to 49 


10 to 17 


voy leiaima 










forett 


a 


3to4 


retarded 


Steppe 


4 to6 


ltoI,S 


in tensive 


Subtropical 








foiett 


10 


a7 


loMHhfe 




llo2 


0.2 


vwyialiashw 


Eqoaiarial 








fOfMt 




Oil 


veiy intcittivB 




Mft Omt of Um yaar 1 


Hd cypa orimeea. 





after a perturbation-the shorter the time, the more stable 
the ecosystem. They show that the cyde of essential 

nutrients (such asCa. K, Mg. Fe and Cu) are stable; nones- 
sential elements, such as Na imported by sea spray or ' ^ ^Cs 
injected in tree stems, are not recycled in the Uvii^ com- 

partments of the eco^vstem. 

During the evolution of eco^stems from the early devel- 
oproent stages until the mature cUmax stages, important 
modificatlom affect the cydei (Odnin, 1969): 

~ extiabiotic nutrients become more and more intraMotic 

- cycles, initially open, close progressively 

- the rate of nutrient exchange between organisms and 
thiir emirannient, initially quick, becomes rioir 

- dM id* played by detritus in the fcminenllxatioii be- 
comes more and more important. 

During a succession, as a rule, one ecosystem promotes flw 
conditions of soil nutrients for the following one (improve- 
ment ot sylviculiural properties of the soil by the plants 
themselves) (Remezov and Fogrebniyak, 1969). TUi phe^ 
nnrnenon is aptly illustrated by the manipulated Wlimhed 
studies of the US/IBP (Table 3). 

Mnaral Cydbii and SysMn Analysis 

Recently, system analysis has been applied to mfaieral cycling. 

The studied ecosystem is divided into coinp.irtmcnts. tbe 
nutrient content of each compartment and nutrient transfer 
from one of them to the other w established. For each 
compartment, a differential equation gives the change of 
content, which equals the difference between what enters 
and leivei that compartment. These equations are solved by 
computer and constitute the mathematical model of the 
mineral ^cliiig of the eco^stem. If tbe transfer coefBcienta 



oopy I lytiiC'u niaiufial 



146 



p. OUVIGNEAUO and S. OENAEYER-OE SMET 



for the moM important compartinents are known, it becomes 
pooible to predict the dynunics of nutrient concentntions 

in various ecosystem components (at least if the ecosystem 
is still functioning m the same way as when those transfer 
coeffieleiits were eitabUihed). 

An interesting experience consists in modifying (with 
computer) the content of one kumpariinent or the value of 
a flux of file model and to obierve the efTeets on the whole 
ecosystem. In this manner, it is possible to point out the 
most sensitive parts ot the model ecosystem and to develop 
appropriate research programs. Such mathematical models 
are of particubr utility m studying eco^siems Submitted 
to toxic element pollution. 

MINERAL CVCLIM6 AND ENVIRONMENTAL 
POLLUTION 

Research on mineral cycling isofgrcat interest when toxic 
elements are involved, because the knowledge of their dia> 
tribution and transfer pathways through the different com* 
partments of the ecosystems allows one to detect their pos- 
sible accumulation along given food cliains. In Sweden, for 
example, the study of S cycling in forest ecosystems (Table 
1) has shown that rainfall carries into the soil very high 
quantities of sulfur (mainly hl}S04 ) which acidify the upper 
layer of the soil and are responsible for an increased nutrient 
leaching whidi will probably affect the prinutv productivity 
of the i-L;i)s.vsterTn Thi* same phenometuKi slso has been ob- 
served m Cfcrmany and the U.S. 

Another example is the faiput of heavy metals (Zn, Pb. 

Cd. Cr. Ni) originating from industrial activities and roadside 
emissions which contaminate the aerial parts of vegetation, 
pollute rainwater and accurmtlate in dead organic matter, as 
shown hy Tyler (1972), for sever;i1 ts pcs of terrestrial and 
seashore meadow ecosystems in Sweden. A detailed study of 
Cd distribution in a eontminated spruce fbrest (Table 5) 
shows that Cd accumulation is highest in the most decom- 
posed organic matter (humus layer) from where it may be 
absorbed by ihatlow-rooted plant species. Plant to animal 
transfers already demonstrated for Pb by Schwickerath 
(1931), have been observed recently for Cd in Great Britain 
Ideath of horses having consumed contaminated feed (Ciood- 
man jiid Roberts. 197l)|, 

Another interesting aspect of mineral cycling is the study 
of elements chemically analogous to toxic elements and oc- 
curring in undisturbed ecosystems, as for example, stable Sr 
whose behavior is probably very similar to that of radioac- 
tive '"Sr conlammaiing several ecosystems as a consequence 
of nudear aclivitiet (Alexahin and Ravikovich, 1 966). 

BI06E0CHEMICAL LANDSCAPES 

Starting from Dokuchaev'<i conception-- (!SS<r IRSfi. ]Hm) 
on the /onality of the soils and coriespondmg vegetation, lite 



TABLE S Cadmium Contant of a Spruce Forest in Central 
Sweden Pdlutad ftona a LaesI Imhistrial Sowce (After 

Tyler, 1972) 



Forest CompoOCTt wg Cd/Diy Mailer 



roots <5 nun iKaneln 


2.7 


roots '5 mm diomettr 


1.5 


stem wood 


<0.1 


stem tnrk 


IS 






1 St year 


Sw4 


2nd year 


*A 


9rdycw 


4.2 


4lh year 


3.3 


5ih-7ih year 


2.7 


Nwdlcs 




Isl year 


0.6 


2nd year 


0.4 


Jidyear 


0.S 


4tliyear 


as 


5ih-7th year 


IjO 


yoccinium vitis idaea 




J t>i ' V 1- ^: r < 1 u biomaw 


3J 


Vaccinium myrlillus 




at>oveground biomtH 


4.4 


DacHQmptia fleximm 




iMvei 


lA 


leaf litter 


12 


root* 


11 


Parmelia physodn 




wliole plan! 


12 


Hypnum cupren^bimt 




whole plant 


30 


Nesdis Utter 


24 


RawhiuMis 


44 



"natural landscape" has been defined as an area where relief, 
climate, vegetation and soil characters are considered as 
forming a harmonious whole which repeats itself along a 
given terrestrial /'one. !n tli-,' classical study on "Landscape- 
Geographical zones ol the USSR." landscapes were classified 
as follows: fades lamlscape -*' aomr. Fades oomapond 
nearly to the biogcoccnosisof Sttkaehev(l947)andlOlhe 
ecosystem of Lindeman (1942). 

In one and die same landscape, the lateral migration of 
chemical ekuwnts links the soils of the elevations, slopes 
and depressions, which form a "Catena" (Milne, 1936). 
characterized by an eluvial (top), colluvial (slope) and illuvial 
complex (depression) to which correspond ccosocidogie 
groups of plant species (Duvigncaud, 1955). Water move- 
ments, which are o( prime importance for this topographic 
ecology were studied in 1928 by Vysotskii. At a more 
"mineral" level, this concept of chemical unit of landscape 
has been used by geologists (Pcrebnan, 1964; Glazovskaya, 
1968) «dio initiated studies on the iaadacape biogeodieiiiiitry. 

The type of rockweathering and of transformation of the 
dead organic matter in tlie eluvial complex arc important: 



Copyrighted material 



MinilALCVCUNO INTniRfSTmAL iOOmTBMB 



147 



fion fhli bdetennteed the comporition of water ranning on 
Ibeilope (transalluvial or transaccumulative complexes) and 
•ccumuUting in the depressions (accumuJative, often "supB^ 
Mquous" complexes) where it forms very shallow tables. 
The difference in ntobHity of the chemical compounds dis- 
solved in the eliivial complex (orrrn geochemical sequences 
very typical ui deserts. The classical sequence observed in 
Oieoolddaiertit: 

F«,O,<llB0<aC0,<Na,SO.<CaCl,. MgO,. (NaO). 

The same cKcurs in hot desertS, ptttS M iMeicafaltiOll of 
CaS04 and nitrates. 

In more Inimid Imdscapes, solifliictton compUeites the 

situation and soil depth increases at the bottom of the 
iopei. Glazovskaya (1968) shows that in the subarctic catena 
in Sootlind. Noiwty and USSR Hie hi^ mobfllty of Al 
versus Fe depends on the mobility of the complexes of tliMe 
elements with humic matter: 

Fe* hnnite< F«* flil«ile< Al* lUvate < StO. «iiMnt.CIKHOO,),. 

The moie contrasting geochemicai landscapes (linked with 
Slid climate) are obtained when the eluvial complex develops 
a strongly acid environment, which is transformed in a 
neutral or alkaline one in the accumulative complex whose 
eYipontion is very high. The succession is as follows: top, add 
and fcrruginoii'i soils, slope, ferruginous and neutral soils, 
with Si precipitation (opal); transaccumulative soils in the 
lower pert of the slope (carbonated chernoKfls); aocuniiila* 
th'e bottom soils (solonchak) and salty lakes (Na) studies in 
Siberia and Far-East (Kovda, 1946). The sequence is as 
foOom: 

FeaO, < StO, < CaCO« < N«HCO. < NaCI. 



in less extreme landscapes, with steppe vegetation, we have: 

CaCO, <CaS04 <Na,SO« <Naa. 

So it appean fliat the fiilure of ecology consists of an ex- 
tension of the ecosystem concept to a basin, a catena or a 
geochemicai landscape, where ecological, geological and 
hydtalo|lcal proUeiiui an strongly Unkad. 

WORLDWIDE MINERAL CVCLING-eiOQEOCHEMICAL 

TERRITORIES 

gasaifkaiiwtt of dw Bielogical Cycles 

Wc may not insist here on the tightness of the relationship* 
between biogeocbemistry and biosphere, well-deflned follow* 
big the oonceptkms and tnvestiptfons of Dokochaev ( 1 889), 
Vernadskii (1926) and Grigorieff (1965). 

Since 1965, Rodin and Bazikvich (1967) have amelioiated 
continuously s daasiflcatlDn of the world btomes in terns 
of their type of biological cyde. On the basis of the "Xjeog* 
raphy of Productivity" -a main objective of the iBP-they 
established provisionally the patterns of the circulation of 
nutrients (ash elements and N) in the main vegetation types 
of the world, following a zonality of the Russian schools of 
pedology and phytosociology. Tliey first proposed a classifica- 
tion of the types of nutrient circulation based on litter and 
litter turnover. A lO-point scale was used consisting of the 
following parameters: biomass of the climax (B), produc- 
thff ty CP), annual Utierfall (L), decay (D - litter/lltterfaU). 
and the mean nutrient content of fresh litter (Table 6) 

Bazilevich and Rodin (1971) published a world map 
based on a 10-point scale of productivity and dw dominant 
nutrients of the carrying capacity (Figure S); the basic net- 
worlc is the map of the vegetal formations from the "Atlas 



TABLE 6 W«fW aassHlcateii of IMnsrai Cydlna (Afiar Rodin and 

Aril Content 



i.1W7» 



Oau 



Group 



Productivity 



Cyck 



Vegetation 



Equatorial 



N4IOa 

NO 

N 

N»<:i 



vary high 



low 



low 

vety low 



very intensive 



Equatorial forest 
Si :> N (Al Fc Mn-S) 
BIO. P9, L9.D9,AS 

Temperate (toddaCHS fbMtt 

ltt,P7,U,06.M 



N»Ca(K,Mn) 

B2-3, PI. I 2, ni-2. A7 
Semideterts on Solunchiik 

a > Na > N (mg-S-t a) 

BI-2. Pl,Ll-2. DIO, AlO 
Stc|)pei 

SI>N(KM«ii««iiiibO 



GopynghleO maienal 




oopy I lyf liC'Ci niaietial 



ISO 



P, OUVKMIEAUD md t. DEKMfVSR-DE HIET 



of Physical Gcogn|riiy of the World " (Seoderon. 1964). 

Following parameters were used: phytomass. NPP, mean con- 
tent of tlie primary productivity (leaves, stems, roots) and 
"einying cii|»eity" of the Uologicil tydt (we p. 13S). 
which depends on the quantity of organic matter produced 
and on the structure of the phytocenosis and tlius on the 
dooiJniot life fomt The nuqitof the diemieal compodtion 
and types of biological cycles show the importance of 
ifodal zonality (chemical and geographical) on biogeochemi- 
cal^dn: 

- N dominance in peat, bogs, tundra fomts, conifer- 
out and nnall kaved foiests, hrnnld subtropical forests, 

- Si dominance in steppe formations, 

- Ca dominance in broadleaved forests and steppes, 
adominanoe In nit deiefta. 

Several regularities appear-maps of annual absorption of 
Ca and N may be superimposed on that of carrying capacity 
(N alMorption depends directly on npp and P absorptloiili 
very low in steppe and desertic formations). Phosphorus!^ 
pears to be insufficient in the broadleaved forests of sub- 
tropical and humid regions (perhaps because of retention of 
P as PjOj which is very abundant in soil). Potassium ab- 
sorption does not seem to be sufficient in steppes and broad- 
leaved forests, at least with regard to die oAsr nutrienta. 

A detailed study of the biological productivity and 
mineral cycling of terrestrial communities of USSR has 
been puhUdud neently by several Soviet IBP workeis (BaiOe* 
vich and Rodin. 1971). Several maps have been estab- 
lished following the same principles used in the would maps 
discussed earlier. The following data (TaUe 7) riiow how, in 

some cct)systcms, the accumulation of dead nrpanic matter 
may retard considerably the biological cycles of elements. 

Biogsochiinicil Tstiiloviaa 

The concept of biogeochemlcal landscapes may t>e extended 

to entire regions characterized by either the abundance or 
dominance of given geological conditions. This concept was 
mainly developed by Soviet scientists influenced by the 
soil zonality of Dolcuchacv. Following Kovalsky (1963), 
the USSR may be divided into biogeochemical territories 
corresponding with the large phytogeographic zones: taiga 
or black earth (excess of Co, Ca, Cu and I), woody steppes 
and steppes on black earth (sufficiency of Co. Ca, Cu and I), 
dry steppes, semideserts and deserts (excess of Na, Ca, CI, 
8O4 and B), mountains 0 md sometimes Cu and Co defi- 
ciency). One of the most interesting aspects of this special 
geography is the fact that it corresponds to endemic dis- 
eases: goiter by 1 deficiency : endemic gout when Mo is moie 
abundant thjn Cu; endemic dwarfness when the Si/Ca ratio 
is too high, and enterite by B excess. Recently, fiazilevich 
and Rodbi (1971) have puUftfied a map of die eontbients. 



TABLE 7 Comparison of the Rapidity of the Bidoflical 

Cycling of Elements with the Amount of Accumulated 
Litter in the Ecotyttem (After Bazilevich and Rodin, 1971) 





Fonnation 


Accumulated litter 


2 


desert 


0-5 l/ha 


3 


nibdesert 


0.5-2 ? t.Tia 


4 


mbtfopkai 


2.5-7.5 t/ha 


7 


ModnroiaMi 




8 


eenUinwisibfaits 


4(Met/ha 


9 


foKsts and twiffip 


60-100 t/ha 


10 


forests and twampy 


>I00t/hB 



soils with musses 



'indkalc* relative rapidity of the biological cycle of elamenti, from 
rapid (low ■uraban) lo alow (hltfi aimitort) MotyalaiDi, 



rilowing that, as well as the flora, biogeochemiatiy diancter- 
izes the main biogeochemical territories. 

More recently. Cannon (1969, 1970) demonstrated that 
the USA may be divided into several biogeochemical prov- 

incies, e.g., limestone areas of the Eastern USA (possible 
excess of P, K, and possible deficiency of Mo, Sr, Ca and 
Mg), coastal plain sands (possible deficiency of Fe, Mr, Cu, 
Co and Ro). the shales of the northcentral plains (excess of 
Mo and Se and possible deficiency of P), the evaporative 
baaint ^oniUe eaieeii of SI and deficiency of Cr inducing 
endande diabotea by Indian peoples). 

Kegaoeheniical Epidemiology (Diseases induced by bio- 
OSoolMMiBal anomallas) 

Mological anomalies may modify the chemical composi- 
tion of plants serving as a food source for consumers.* In 
some regions of the world (USA and Central Asia), bedrocli 
contains Se In amounts a little hitter than typteal sofls; 
by shedding of the aerial organs of some "concentrator" 
plant species Se is brought to the soil wrfacc and then ab- 
aoibed by meadow or cultured plants wideh transform Se In 
toxic forms for consumption by animals and men (several 
kinds of seleniosis). Similar phenomena are induced by the 
deficiency of some elements essential for animals and men, 
e.g., cattle rachitis induced by Co (conititueiit of vltanki 
Bi a) deficiency of grass. 

The most spectacular case of element deficiency is the 
goiter, wliich frequently is induced by an I deficiency 
(regions far from the sea). Before the administration of 
afiilicaliy I enriched food, goiters killed 10* pigs/year in 
Montana (USA goiter belt). Observations in Great Britain 
and in the Netherlands she w that goiters also depend on the 
nature ot the bedrock: carboniferous and doiomitic lime- 
stone seem to Ikvor goiters, whereas ehaUgr and MUjptfan fodtt 

* The limpleit ensile it livn by die eoeumuMon of a toxle 
eteaiMt aloeg a isophlc cImIb. 



Copyrighted material 



MINERAL CVCIINO IN TSmmTIMAL fCOmilM 



161 



do not. Samyi owdt in Engbnd, Wdes, Normuidy and 
Nefheilmidi draw « portttn correlation between mortality 

by gastric cancer and the organic matter content of culti- 
vated soils (Legon, 19S2); organic matter content is especially 
high in boggy regions and in valleys with clay soils ("cancer 
valltys") Low organic soils suffer from a deficiency of 
available Cu and from an excess of Zn, Co and Cr. Some 
psopk ooraider this dietny taibahnce to be responsible 
for gastric cancer. The issue remains scieniincally unre?olved. 

Certain forms of esophageal cancer are linked with given 
icgioiis of the world, for exunfrie, in weitem China, esoph- 
ageal cancer is linked with the cotton agriculture. The 
cancer rate in most regions with highest incidence is 100-200 
times higher Hkm in other regioni. Such diffcrencei may be 
observed over a very short distance. In certain regions, this 
increase in esophageal cancer has occurred recently. Esopha- 
geal cancer leema to be a *^u]nea pig** for itodylng the 
relations between certain factors of our environment (food 
is probably the roost important) and human diseases. It 
it dio an important way to study cancer origin. TUs is the 

reason why many studies arc in progress now in the esopha- 
geal cancer belts of Africa and Asia. On the Caspian Sea 
shore, a very high esophageal cancer rate (1.1 percent In 
men, 1 .7 percent in women) affects turcoman population of 
the northeast; this region is semidesertic with a predominance 
of salty soils (Anemisfa and Astragalus steppes) wifli a vary 
high pH which reduces the availability of Fe. B, Cu and Zn. 
Human food in this region is lacking in anhnal proteins, 
vitamin A, riboflavin and vitamin C. The regions with the 
lower cancer rate have a vary high rainfall and associated 
soil leaching and, as a consequence, a type of agriculture 
with higher Fe, B, Ca and Zn content of crops (Kmet and 
Mahboudi, 1972). These observations may be related to thoae 
made in Transkei (South Africa) where severe esophageal 
cancer affects the Bantu population in a region with high 
soil erosion and a more vegetarian diet. It seems that the 
juice ri( Snlanum incanum used to curdle milk is responsible. 

In Iceland. Armstrong (1964a, 19646 and 1967) could 
not find a relationship between stomach cancer and the eon- 
tent of 22 chemical elements in vegetables, milk, water and 
herbage of grasslands, in iCenya, Robinson and ClifTord 
(1968) did not find significant differences In the content of 
8 chemical elements in Zca mjv<;, growing near farmhouses 
and the nose-pharynx cancer rate, in the USA several meet- 
ings have been orga n ized: "Tnee substances hi env i ronme n tal 
health" (Cannon. 1969-70) and "Geochemical environment in 
relation to health and disease" (Hopps and Cannon, 1972). 
Reports overviewed the inhibitional action of trace elements 
sudi as As, Cu, Pt, Se and Zn, on neoplastic growth (Pories 
etal., 1972), the antidiabetic action of Cr, the relation be- 
tween Cd and high blood pressure (Perry, 1972), the inverse 
relation between water hardness and the entire group of 
cardiovascular diseases (Correa and Strong, 1972). Feeding 
pattenu are very complicated, even in the most primitive 



societies and it is necessary to take into account the food 
allocation along food chains, the cooking and food prepare* 
tion methods, dietary preferences, etc. Collaboration is 
necessary between geologists, ecologists, agronomists, and 
MocltemiMs having a common interest in MogeodMmistiy 
and the consequences on human health. 

This modern aspect of ecology -biogeochemical epidemi- 
ology-also concerns health problems in relation to technology. 
For example, the addition of an excess of nitrate to a soil 
lacking Mo may induce accumulation of carcinogenic nitr<»- 
ambie, because of the poor N metabolism of the plants. 

CONCLUSIONS 

Mineial cyding is one of the most important parameters in 
the analysis of ecosystems, because mineral elements, as 
much as energy and water, are essential to maintain the con- 
tinuity and stability of these systems. Although the processes 
of absorption, retention and restitution of mineral elements 
are not yet well known at tfie ecosystem level, comparison 
of initial data obtained from several terrestrial ecosystem 
types show some general regularities that begin to emerge- 
Mineral cycling appears to be one of the best and easiest ways 
to characterize the general metabolism and functioning of 
ecoQTstems, but many yean are still required (several IBP or 
SCOPE programs) to obtain sufficient data to make valuable 
models and predictions. 

Knowledge of mineral cycling is of greatest practical in- 
terest in agronomy and forestry, because it will allow us to 
provide the highest utilization of the solar energy in the 
productivity of plant communities. It will optimize the 
utihzation rate of fertilizers by selection of the best eco- 
system types in relation to environmental conditions ("bi- 
ological agriculture" leading to a ma.\!mum of productivity 
and quahty). Mineral cychng studies should also give a good 
idea of the rale played by badrodc in die nutrition of te^ 
restrial ecosystems. 

The accurate knowledge of mtnei al cycling will allow 
eeoiogisU to make piaetical wcom m endatlont for better 
quantitative and qualitative productivity The cycles of 
mineral elements at the eco^stem level combine to form 
die overall mtaeral cyde at the Woaphen level, upon which 
depends man's future. It is only with a sufficient knowledge 
of these large cycles that it will be possible to make quantita- 
tive predictions and answer some of the pressing environ- 
mental questions. Is the earth in process of eutrophication 
by an increasing nitrogen enrichment, or in the process of 
dystrophication by a blocking up of the phosphorous cycle 
in the deep oceans, or in the process of acidification by sul- 
furic and hydrochloric acid? What are the global effects of 
biotk: pollution by lead, cadmium, mercury? So many que^ 
tkmiiddch it will be possible to ansirer only if we know ac- 
curately the cycles of dements on an eooqfstem and bio- 
spheric level. 



Gopynghled maienal 



152 

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Copyriytiica rnaicrial 



HYDROLOGIC 
TRANSPORT MODELS 



D. D. HUFF 



INTRODUCTION 

There is little question that wutei is a key factor in virtually 
iD ecosystemt. Yet, anening the importmce of water in an 

ecosystem in precise quantitative terms is an elusive goal. 
Two factors have arisen over the past decade, however, to 
bring diat god cloier to a ledity than ever before. The 
first factor is the recent hurst of progress in computer hard- 
ware and software technology, in particular, the storage 
capabBities and speed of computational openrttona hanre 
fmally made it possible lo deal in detail with proUenu 00 
the scale of natural environmental systems. 

The second factor is an emerging attitude toward coopera- 
tion between scientists from diverse disciplines. Namely, the 
growfaig wiUingness on the part of many to sacriHce the time 
and effort necessary to establish a meaningful communication 
Hllkwith those in other disciplines. That dialogue can and 
has provided a svnerpistic richnes<i evident in th? results of 
many uf the sludies supported througli the Inicrnaliunal 
Biological Program (I BP). In the spirit of enhancing that 
dialogue, the following material is presented. It is ;in attempt 
to selectively hi^iight aspects of hydrologic transport 
moddbig of prlmaiy {nqwrtanoe to those woridi« within 
the IBP. The review is not exhaustive, however; it is an at- 
tempt to place the role of hydrologic transport modeling in 
a proper perspective idatiw to analyris of ecoiystema. It is 
further hoped that the examples cited will serve to stimulate 
the exchange of information and goals between disciplines. 

166 



CLASSES OF HYDROLOGIC TRANSPORT MODELS 

When hydrologic transport models are discussed with refer- 
ence to analysis of ecoqrsteros. it is useful to classify types 

of models on the basis of the ndysical sy<;tem represented 
and the general analytic tools used m model implementation. 
Figure 1 represents a sbnple dasaifleation scheme which may 
be used to ilhistrrite both the range of passible model types 
and more closely identify a category of hydrologic transport 
rood^ that have received tiie most attention in eco^stero 
analysis leseaich. 

TERRESTRIAL AND AQUATIC SYSTEM MODELS 

it is most convenient to separate ecosystems into either a 
terrestrial or an aquatic classification. It is well known that 
this separation is artificial since the two are intimately con- 
nected, yet. from a practical point of view, implementing a 
detailed model for the combined system is no! operationally 
ftasihieat present. There are examples of very good hydrotoglc 
transport models for both types of systems, but it is a fact 
that the aquatic class of hydrologic transport models has 
reached a level of devdopment weO ahead of terreitrial 
counterparts. To a larce decree, this is a result of emphasis 
on developing water quality models for managmg streams, 
lakes, and estuaries. Altiiou^ the motivations for such 
model development were different from those stimulatlllf 
the IBP, there is a good deal of information available 



Copyrighted material 



1S6 

OIVIL-OWO 74-4171 

HYDROLOGIC TRANSPORT MODELS 

ECOSYSTEM 
TERRESTRIAL AQUATIC 

MATERIALS TRANSPORTED 
POINT SOURCES DIFFUSE SOURCES 

MODEL CLASSIFICATION 
MECHANISTIC MRAMETRiC STOCHASTIC 
FIGURE 1 A diMHlirten mIiwim terliydrflloth IfMupon 

!■■ II liain 

through studying such models. Fortunately, these models 
have been reported widely in the water <iiia]ity literature, 

and those intere';ted in pursuing the availahle information 
may be referred to an excellent review of modeling hydrologic 
transport and corresponding biologica] lespcnue in aquatic 
systems (Orlob, 1972). An article by Simons ( 1972) will 
serve as a good starting point for those interested in the 
modeling of hike dreulatiaa and asMdated sohite tnniport. 
Woolhiser (1973) has reviewed watershed and associated 
water quality component models and presents a very useful 
list of references of hydrologic transport models for both 
terrestrial and aquatic ecosystems. Hit review clearly makes 
the point that relatively little has been accomplished in 
modeling hydrologic transport in terrestrial ecosystems, anU 
that auch work must involve several disciplines because of 
the scope <^f the problem. For this reason, much of the 
following material deals vnth terrestrial hydrologic transport 
moddfaig. 

DIFFUSE AND POINT SOURCES 

A useful distinction may he made between point and diffuse 
sources of materials when dealing with hydrologic transport 
and Interaction of mateilali with ecosystems. Gearly, many 
point sources of materials such as outfalls from waste treat- 
ment facilities, irrigation return flow collection systems, or 
industrial stacks discharging to tlte atmosphere, ultimately 
contribute to the pod of diffuse materials in the environ- 
ment. However, because of the relatively high concentrations 
in point sources, it is usudly most important initially to 



evaltiate their effects independently. A good example is the 

extensive body of research on the effects of point sources of 
pollution on water quality variables such as dissolved oxygen. 
Since point sources have been so extensivdy studied, em- 
phasis here will be confmcd to the transport of materials 
from diffuse sources, such as geologic formatioas or litter- 
fall in a forested dninage basin. 

TYPES OP ANALYTIC MODELS 

There are three general types of analytic approaches to con- 
structing hydrologic transport models. The mechanistic 
approach is based upon an understanding of physical 
processes. Each process is repreaanted by accurate mathemat- 
ical expressions, then the processes are linked together to 
form a mathematical model uf the whole system. Linkages 
are determined by the physical q^stem modeled, and Cadl 
portion of the model has a physical counterpart which it 
simulates. The major argument for developing this type of 
model is that it ulthnatdy offers the potential for predict- 
ing system behavior for conditions that have not been ob- 
served in the natural system. In fact, it is only this general 
daas of **theafetical** models that offers the ability to evalu> 
ate environmental impact of the int-nrtuctiun of new sub- 
stances or new land or water use pohcies prior to actual 
implementation (Woolhiser, 1973). A strong counter aign- 
ment (or at least a limitation) is that even though a system 
may be totally deterministic, it is not possible to describe 
the qrstem in enough detail to predict its behavior mechanis- 
tically. 

A second type of analytic model formulation is parametric, 
which is chinciMixed by compartment type models (com- 
partment type models can also be mechanistic) based upon 
linear regression representations of system and subsystem 
behavior. At the present time, parametric models are probably 
the most useful of the three types for ecosystem modeling 
because of their empirical base and their ability to describe 
complex systems with simple inathemaucal expressions. A 
fine example of apaninetric model is the ELM (Ecosystem 
Level Model) (Anway etal., 1972) developed by modelers 
in the Grasslands Biome portion of the US/IBP Analysis of 
Ecosystems (AOB) studies. The maior point of difl^noe 
between a mechanistic and parametric model is that the loss 
rates lor a storage in a mechanistic system will depend on 
known physical taws and the state of the tystem . In a paia- 
metric model, the transfer rates are determined fiom aiialy* 
sis of ^stem response without attempting to explicitly 
describe individual contributbig processes. 

Finally, stochastic models describe or recreate statistical 
properties of observed variables of the ^stem and are baaed 
upon probabilistic considerations. For example, a stochastic 
model could be used for generating a synthetic temporal 
sequence of cation flux from a watershed. The statistical 
properties of the qmthetle and obaemd records for the 



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HVDROLOGIC TRANSPORT MODELS 



157 



basin, such as monthly mean, variance, and serial and cross 
condilioni iritt odier puinelen, would be ttulic^ 



HYOROLOGIC TRANSPORT MODELS FOR 
TERRESTRIAL EOOtYSTEMS 

The focus on "proorai itodiet** wKhin the IBP most appropri- 
ately leads to emphasis on a specific type or hydrologlc 
tmuport model: terrestrial, diffuse source, and of a pre- 
dominantly deterministic and mechanistic type. One key 
concept in the development of such a model is that water is 
a carrier of materials, thus modeling hydrologic transport 
of materials may be accomplished by linking chemical and 
biologied tiansfonnations of materials within an ecosystem 
to the presence and movement of waier The logical point 
for beginning the discussion is with a hydrologic simulation 
modeL 

HYDROLOGIC CYCLE 

Figure 2 presents a diagram of the most generally important 
components of the hydrologic cycle in schematic form. It 
baboanpieaentatioaofaflawdiait foracompiebendve 
liydraloi^ limulalion modd wch at that pieMnted by 



MTCIKCPT«*| 



i 



-mwKenm 



± 



UPPU KMC 



*V/klLlSLC 
1 MOIST UHC 














OVEUl H>tC F.J* 
Of 'f MiC»> 4T0<<£C.E 









mm 
Kmv 





i><rc»F4.0W 
OCTCNTlON 



LOwe* ZOMC 
ST0««6E 



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Lr 



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5«OuN0 l»»rE» 
STCWMC 



iNacnvc WOUND 
i 

Mtm LOSS 



e*SIN LOTS 



FIGURE 2 AKhwnatic 
elMWii 



of Km ino»t imiMrtMit 



Crawford and Linsley (1966). Precipiution is divided be- 
tween that hdd as tnterceptlon atorsfe on the huia canopy. 

and the through f.ill portion which reaches the basin sur- 
face. In climates where snowfall is possible, an additional 
snowpaclc storage component is added and the molsluie 
delivered to the basin surface is that which is released from 
the snowpack. ThroughfaU is further divided between the 
portion raaehing iinpervioas and pervious surftces to ob* 
ttin both impervious area runoff to stream chaniieb(bh 
dudes water falling directly on channels), and the incranen* 
tal addition of water to the moisture supply available at 
the l>asin surface at any time. The available moisture sup- 
ply may either inHltratc into the soil profile (subsurface 
water supply) or be partitioned into any one of three storage 
eomponents. The upper zone storasa wp ie a e nt a depnadon 
storage on the basin surface, more commonly known as mud 
puddles. The interflow detention storage represents a frac- 
tioa of stoim runoff with a delayed input to the basin 
drainege network. Row from this storage Is termed inter- 
flow and is assumed to have a rate direcdy proportional to 
the <|ii8ntlty of interflow detention storaga. It is often stated 
that interflow represents lateral, shallow subsurface flow to 
the stream channel, however this concept has recently been 
challenged (Dunne and Black, 1970). 

If infiltration rates are lower than the available moisture 
supply rate, water may move across the pervious soil sur- 
face. The quantity of water moving over the basin surface 
at any time is termed overland flow detention storage, and 
the flow rate to the channel may be expressed as a function 
of this storage fnm considerations of open diannd hydraulics. 
Note that overland flow detention storage as well as U|^r 
zone storage are both available for subsequent infiltration. 
Of the quantity of water infiltrated into the soU, a portion 
remain! as sod moisture in the upper horizons of the soil, 
and some may percolate downward into the saturated or 
groundwater zone in the basin. The active groundwater 
storage feeds directly into the basin drainage network and is 
measured as base or "dry weather" flow. The inactive ground- 
water storage represents groundwater lost from the basin by 
any of several processes. For example, water pumped for 
use in a municipal w.'iter supply system, then diverted out of 
the basin through a waste treatment plant would be included 
in the inactive groundwater category. Evapotranspiration 
may occur from any of the storages. Inflow to the stream 
channel, consisting ol impervious area runoff, overland flow, 
interflow, and groundwater flow is bunidooed faito the ap- 
propriate section of the channel system. The entire com- 
bined tlow is simulated section by section from the moat 
remote parts of the dumnd system to the basin outlet. 

In addition to explicitly quantifyinp fnur separate com- 
ponents of flow to basin channels, several basin state vari- 
dries (sudi as sod water content) are also sbmilated. These 
variahlos have great utility for modeling ecosystem processes 
such as primary productivity. Thus, the framework for the 



GopynghleO maienal 



158 



0.0. HUFF 



bydidogie model can wrve u t put of the physical deicflp- 

tkm of the state of the hasin eooqntem 

The fact that there are four aaparate sources of water for 
streamflow becomes important when it it recognized that 
the chemical quality of the water is highly dependent on its 
past history. The must significant changes in waterborae 
materials content probably occur when the water comes hi 
contact with the soil and litter surface. Therefore it is appro- 
priate to begin the discussion of examples of hydrologic 
transport models with a review of some research on solute 
tiinqMxt in flofls. 

HYDROLOGIC SOLUTE TRANSPORT IN SOILS 

A very generalised formulation of a combined model for 
water and salt tlow in soil has been presented by Endclman 
«r cf. (1972). A schematic diagram of the model and associ- 
ated equations is shown in Fipure 3. In simple terms, the 
model is a statement ot the prmciple of conservation of mass, 

0RNL-0W6 74-4168 



WATER AND SALT FLOW 

(cv)( [-D{dc/dz)]^ 




9 »-K(9)(aH/dz) 

d(ec)/at = -d{cv)/dz + d[eD{dc/dz)]/dz + 2R^ 
BASIC EQUATIONS 

FlOUIIf) AMiMniMledtapMiofaiollwatirandatftfiow 
■MM, and aaeeiaiad uMaMiw (aftw iMlslManMefc, 1*ni. 



coupled with tiie Duty law for one-dbneniional (vertical) 

flow of water in soil. The figure shows a volume element of 
unit cross-sectional area and length /^z. A fraction of the 
volume element (e) is occupied by the carrier, water. Two 
transport processes are considered. Convective flow trans- 
port ((cv)s] represents transport of material carried along 
by the water in terms of solute concentration (c) and 
carrier velocity (v). Dispersive transport { (-IXdc/dz)) , } 
represents movement of material relative to the carrier by 
virtue of a concentration gradient along the flow path. An 
additional term, the net rate at which the sdute is con- 
<;umed. produced, or transformed (R|) withio the control 
volume, IS also included. 

For ippUcation of die model, the ccmtinuity equation 
for one-dimensional water flow is solved to determine 
volumetric water content within the soil profile at some 
potat in time, t This profile may In lium be used to derive 
the velocity (v) profile for water flux and then to solve (he 
general equation for salt transport between layers in the 
soil. 

An example of the results produced by a model of this 
type, as compared to field observations, is shown in Figure 
4 (Gupta. t972). The research was conducted at HulUnger 
Farm, ne i; Vortiiil, Utah, in cooperation with the I'S'IBP 
Desert Biome program. In Figure 4a, computed and measured 
soil water content profiles at selected times are shown. The 
profiles resulted from a wetting and drying cycle. Figure 
4b shows computed and observed salt concentrations at the 
same thnes. The prooedwe used was to apply crystdHne idt 
to the soil surface. ini|ate, then aUow the soil to diy for an 
extended period. 

One rather interesting outcome is the model prediction 
of an upward water flux in response to evaporative stieai 
(Figure 4). For purposes of modeling salt movement, three 
basic chemical processes were considered as influencing net 
rite of comumption, production or exchange wlthhi a layer: 

a. Dissolution or precipitation 

b. Ionization (dissociation) 

c Ion exchaoie between soil and water solutiooi. 

By using simultaneous equations rep res e nting the three 

processes noted, together with computed water Tuxes, the 
computed concentrations shown in the lower half of Figure 
4 were derived. Even though the materials consideMd weie 
limited to the cations Ca**, M?**. and Na*. and the CI" anion, 
the implications for modeling movement of more complicated 
chemical spedes sudi as N, C and P compounds are encourac- 
inc: It must be clearly unJorstuod however, that much work 
yet remains before models of this level of resolution will be 
available for general simulation of transport of N, C. and P 
througli ecosystems. 

The work of Gupta (1972) addressed determination of 
the diemical quality of irrigation return flows, whidi dtouM 



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HYDROLOOIC TRANSPORT MODELS 



159 



OftNL-OWG 74-4169 
— — COMPUTED 

• MEASURED 



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L 



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VOLUMETRIC WATER CONTENT (cmVcm^) 
(«) WATER COMTCNT PROFILES 



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0 wo 200 O 100 200 0 100 200 

TOTAL SALT CONCENTRATION (meqAttrl 
(^i) SALT CONCENTRATION PROFILES 

FIGURE 4 RMulttofaMUwatgrMdMltllawmoMiliiiiMioa 
»r W Mi wur iniMm WHi |b) nit ■ui—iliMiiiii uwipMiil 



1RU«P|RKTI0N I 



SOIL LAYERS 



TfUkNSMlSSION BWE 




SATURATED ZONE 



inpnparingl 



be considered as point sources of solutes. To illustrate how 
work of this sort tnty be used on a basin-wide scale, it is 
tiaefiil to cumine a diffeMnt levd of RSofaitioD in piedicthw 
hydiolQile ttmaport moddi. 

BASIN WIDE TRANSPORT MODELING 

Foe purposes of watershed scale hydtologic transport models, 
Figure 2 ii muftntive of the genenl itiuetuie and hydndogjte 
components which are explicitly considered. Figure S shows 
the physical tepreaentation of a typical basin segment. The 
Mpnant fonns Ihs baric alnnrat for watershed modeling, 
ainoediecomMnedeflSectsof oneornore segments may be 
used to represent the response of any watershed. The usual 
sequence of simulation progresses from computing the com- 
plete hydrologic cycle for each segment to passing combined 

inflows Ihron^^h the sUcam channel system to generate a 
runoff hydrograph (discharge versus time) at the basin out- 
let. In the ptoceii, the hydrologic State variables of tlw bain 
SI* allowed to vwy with time, and it is ponible to obtain the 



quantity of any individual component of flow into the chan- 
tidatany tiaie. 

HYDROLOGIC SIMULATION 

As an example of basin-wide hydrologic simulation, Figure 
6 depicts a total flow hydrograph that has been disaggregated 
uito its sonidated components (Shih et al., 1972). The study 
ham is the H. J. Andrews Experimental Catchment, which iS 
a focus for US/1BP Coniferous Forest fiiome research. As a 
dm step hi that project, the observed hydrographs were used 
for comparison with simulation results to calibrate the water- 
shed model. (Note that for clarity, the scale used for pre- 
senting surface runoff is only 1 7% of the other two scales.) 

One hnpOCtSnt point to be made from Figure 6 is that 
there are four components of the total flow which can be 
isolated. Clearly, tiicrc is a reasonable probability that some 
compensating errors are pnsent between the flow components 
riiown. in other words»it is poariUe togtt a "correct" total 



Copyriytinju rriaicrial 



160 



O. D. HUFF 



15 



OAML-OWG 74- 4<66 

H J ANDREWS Flow components 



W - 



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2 12 



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coMPurco 

• MEAfURCO 



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I I I I I I r 

TOTAL FLOW 



I I I 



4 

#1 



1 1 1 1' 



1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 

BASE FlOW 

— — MTCKFLOW 



SUBSUMmcC FLOW 




« - 



I I I I I I I I I I I I I I I I I I I I I I 
— — SURFACE SURFACE fLOW 

— CHANNEL 




tscs 



196S 



FIGURE 6 Otoagsragatwl total flow hydrograph for ih« H. J. 
Andrmn ExiMriNNnMI C md t um H t lor 19S3- 1966 (•ftw Shih 
MM, ItTll. 



flow lifflubtloin with lonm enon in individual eomponenU 

of flow Note, however, t^3t 5ince one generally expects very 
significant differences in solute concentrations among the 
various flow eomponenta, it is mucli less Idcdy tiiat com* 

pensating errors in simulations cnn adeciu:if<?ly reproduce ob- 
served water and solute fluxes at the same time. Thus, the 
SKowaUe tolerances for error in a detailed hydrOlo^ trans- 
port model arc even more stringent than those for general 
hydrologic simulation models. At the same time, with more 
information availabte, it is lilcely that it will be posslMe to 
further reHne hydrologic simulation models tlllQU||l studies 
of liydrologic transport processes. 

TRANSPORT SIMUI^TION 

A study by Thomas et a/. (1971 ) may be used to illustrate 
the combined use of detailed and basin-wide type simulation 
models The overall model contains both parametric and 
mechanistic components, and gives an indication of how 
model types can be oombined. One objective of the study 
was tostanlate water qpiali^ and quanti^ in Hie Bear Mver, 



Utah, drainage basin, especially as it is influenced by irriga- 
tion return flows with Mgh salt concentrations. 

Tlie model may be separated into three general subsec- 
tions. They include hydrologic simulation, estimation of salt 
content in natural flow, and detailed examination of irT|BS> 
tion and corresponding return flow salt concentrations. A 
model following the work of Dutt et al. (1972) and Gupta 
(1972). was used to obtain computed values of the quantity 
and salt concentration of return flows from specified irrigS' 
tion practices. In addition, a general hydrologic model was 
used to compute hydrographs of natural flow at several points 
in the Bear River Basin. Tlie fliird oomponent of the model 
used derived correlations between salt content and quantity 
of natural tlows at selected locations in the basin. During 
simulation tests, natural flows were calculated, then used 
to derive corresponding natural salt concentrations using 
regression (parametric) equations. At ilie same time, the de- 
tailed salt flow model was used to compote die magnitude 
of water and salt quantities in irripation return tlow. Finally, 
the natural and irrigation return tlows were combined to 
almttlate tlie total water and salt flux for monthly thne In- 
etements. Figme 7 pnsents some typical oompariaons of 



(■10>) 



OANL-OWG 74-4I6S 

COMPUTED 

• MEASURED 



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o: 



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"I ' I ' ' > 1 1 — I — I — I — i—p 

(a) MONTHLY HYOROCRAPH 



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Copyrighted material 



HYOftOLOGIC TRANSPORT MODELS 



161 



observed and simulated water (Figure 7a) and sait flux 
(Figure 7b) quantities. 

Although agreement is rather good, a significant share of 
the calcium flux originated with natural (diffuse) sovirces, 
and was derived from direct observation using regres&iun 
mediods. For tfibienon, the iDOddwouM probably not be 
a good predictor of water quality if basin conditions were 
significantly altered. However, the model does have great 
Utility for InvestigiitinK the impact of a variety of irrigation 
schemes on the salt content of total flow. To make such a 
model useful for predicting the effects of basin modification 
on idts origiiittiiig from diffiise aouioet, a mon completely 
mechanistic treatment of ill aspects of hydrologic tmnport 
is required. 

MECHANISTIC HYDR0L06IC TRANSTORT MOD€U 

An example of a mechanistic hydrologic transport modd it 

the Hydrologic Transport Model (HTM) formulated by Huff 
(1968). it is based upon a combination of the Stanford 
Watershed Model (Crawford and Linsley. 1966) and chem- 
Miy of lohites transported by water. In addition to the dis- 
aggregation of water fluxes which ultimately prochice stream- 
Oow, explicit consideration is given to the following processes: 

a Interception of wet and dryfall deposition <tf salts, and 
subsequent washoff via throughfall> 

b. Ion exchange proeenet affecting transport of materials 

carried by surface runoff. 

c. Erosion and transport of materials sorbed on soil 
particles. 

d. Percolation of soil water and associated laadiing of 
materials into the soil column. 

The initial application of the HTM dealt with simulating 
the hydrologic transport of radionuclides (' ^ ^Cs and ^"Sr) 
originating from atmospheric nuclear weaptms testing (Huff, 
1968). Figure 8 illustrates some of the comparisons between 
simulated and observed radionuclide fluxes in streamflow in 
Cdiibmia. Althou^ the reauhs were confined to a rather 
special case, the implication of the study was that in principle, 
a mechanistic type of hydrologic transport model is feasible. 

Thus, the United States IBF Eastern Deciduous Forest 
Bioroe program adopted the HTM for modeling transport of 
nutrients Usin;; the same basic assumptions, but adjusting 
the model lor the chemical properties of nitrate (NOj), 
similar studies were conducted at Lake Wingra, Wisconsin. 
nigure9ahows some preliminary results of those simulations. 
It dtould be noted that nitrate was selected for its solubility 
and mobility properties, and that the runoff occurred in a 
storm drain system, thus representing surface runoff almost 
exdusively. None the less, the results again demonstrate the 
feasibility of the approadi. Fertiaps tiie most useful aspect 
of the current versioa of the HTM Is Ibe ttiuctore and bssic 



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1200 



framework it provides as a foundation for more detailed 
fliture models. At present, a m^r revision to the HTM is 

underway as part of the Eastern Deciduous Forest Biome 
modeling work, to attempt to incorporate mote chemical 
and biological procaSMS (ban are cwicntly indoded. 

unuzATicm of nvdroloqic tramifoiit models 

Throi^iout the foregoing discussion , fi cus has moved from 
parametric toward mechanistic, high-level resoUitinn simula- 
tion models. It seems clear that the only means lor develop- 
big truly predictive models lies along a similar path. Furthar- 
more. such detailed models will be required for accurate 
predictive capability in situations that have not yet been 
observed in nature. Thus, It is appropriate that a large pfo* 
portion of the modeling effort in IBP has been ind will con- 
tinue to b« expended on developing and refining these 



At the present state of oomputar tadmology, whole Qra- 



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MANITOU «MY DRAIN 



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- COMPUTED 

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municjition links between disciplines and researchers and 
modelen hu often beeo a dow, fnistnting prooMS. Now 
that many of the linkages have been formcc!, it is imp(irtant 
that they be expanded and strengthened. Hydrologic trans- 
port modeb to date ham conoetitratad pftmariiy on ptqnrical 
processes, and have ignored btoUif^ical processes to a large 
extent. It seems clear that truittui advances can be made in 
undeiitanding the intenelationihipa between hydrologic 
processes, mineral cycling, and productivity. However, these 
advances will depend upon the combined efforts of multi- 
disciplinary teams, well asthoM that now txiit within the 
IBP and the willingness of all adentim to laach beyond their 
disciplines. 

ACKiVOWLEDGMENTS 

The aattior wtihct to thank Dr. J. hui Riley and hi« asiodM«s. tftah 

Water Research Laboratory. Loj;jn. L'lali. for their holplul lugges- 
lionsand willingness to provide hydroloaic sinuibtion results for the 
H. J. Andrews I- xperimenul C-atchnu-r.i I h.mk', .-.it iKn due Dr. J. 
H;ink.s, Utah Stale University, for ducusaons conceinvng water and 
Ki\t (low in soiL 

Support rot the nwarch lepoi ted Ime ms lapplM in pen by 
the Eastern Deefahioui Forest Blome US/IBP. nnHteil by the Natkmil 
Science Foundation under Interagency Agreement AG199, 40-193* 
69, with the Atomic Energy Commisuon-Oak Rkige National 
Labrnitoiy. 



FIGURE 9 SimulaWd and otiaarved ftuxn of (a) watar and lb) 
nitrata for tha Manitou Way ttofm drain in Madnon,! 

I KluMMMf, 1972. 



tam models of a purely mechanistic type are too expensive 
to operate for routine use. Purtfiermore, the data require- 
ments for these mndck arc ofteti so great as to limit applica- 
tions to very well studied situations. Thus, it seems appropri- 
ate that nidi detailed modds be used judiciously and that 
the simpler stochastic or compartment type parametric 
models be used for more routine applications. In this con- 
text, itochaitic models in comUnatioo with datenniiiiitie 
modda may be extiemdy uaelul for kng-tenn studies. 

CONCLUSION 

There are important roles for parametric, mechanistic, and 
stochastic types of hydrologic transport models in ecosys- 
tem Studies. Ilo wawr. lo the Hnal analysis, none of the 
modeling techniques can reach full potential unless the knowl- 
edge represented by all of the disciplines vital to ecosystem 
Studies has been induded in the oomp«ehensive modda pro^ 
duced. The responsibility for developitip su rh models usually 
rests primarily with modelers, yet it is essential that scientists 
conducting basic raseareh also make a direct contribution. 

To date, the IBP studies h;r.c demonstrated that such co- 
operative work is possible, although establishing the com- 



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CONTRIBUTORS 



BAZiLEViCH. PROF.N. t.. Dokuduev Soil Institute, Mokow, USSR. 

BR Y L iNSKY , PROF. M ., Department of Biology. Dalhouaie uiiiirersity, Halifax, Novi Scotls. 

coupland.dk. r. T..De|iutmeBt of Plant Ecology, Uiiiveiiity<tfSid(atciliew^ 

Saskatoon, Canada. 

CRISP. PROK. D. J.. Marine Science Laborator>', University College of North Wales, Menai 

Bfiil|0, Aagtewy, WUea. 
CUMMINS. DR. KRNNETH w . W. K. Kdk)|s Bkdoi^cal Station, Michigan Sute Uoiwrsity. 

Hicliory Corners, Michigan 49060. 
DENABYER'OB 8MBT, s.. Chaigtf de Couif AtiocM, Unheiilt^ Libre de Bnixelki, BniaKit, 

Belgium. 

DINGER. DR. BLAINE E.. Environmental Sciences Division, Oak Ridge National Laboratory, 

Buildiiv 3017, Oik Ridiie, TawNaee 3783a 
DUNBAR, PROF. M.J., MafkiB SciBncM CenlK, MoGill Unimiitjr, Montreal, Quebec, 

Canada. 

DUVIGNEAI7D, PROP. PAUL. DirectcuT, LaborBtoire de Botanique Syat^aUque et 

d'EcoIogic, University Libre de Bnixelles, Brussels, Belgium. 
EDWARDS. DR. NELSON T., Environmental Sciences Division, Oak Ridge National Lab- 

oratoiy. Building 3017, Oak Rii^, Tenneaaee 37830. 
FEE. DR. E. J.. Fii^hcrics Rc!k.-aRh Bturd of Canada,FiBilnnt«rIttatilute,501 Univeitity 

Cieioent, Winnip^ 19, Manitoba, Canada. 
GOLLBY, DR. PRANK B.. Executiw Dlnctor, Institute of Ecokigy, The Rodchoiue. 

University of Georgia, Athens, Georgia 30602. 
GROOZINSKI, OR. WLADYSLAW L., Department of Animal Ecology, Jagiellonian, 

University of Cracow, Cracow, Pbland. 
HARRIS. i)K. w. I RANK. Environmental ScienoeaDMskNi, Oak RidgB National Laboratoiy, 

Building 3017, Oak Ridge, Tennessee 37830. 
HUFF, DR. DALE D., Department of Civil Engineering, University of Wifconsin, Madiioa, 

Wiaoondn 53706. 

KAusHiK. DR N. K., Department of Environmental Biology, Umvcnlty of Guelpli, 

Gue^h, Ontario, Canada. 
LBAN, DR. D. R. 8., Department of Zoology, Unhenity of Toronto, Toronto, Ontario, 

Canada. 

166 



CONTRIBUTORS 



MANN.DR.K.H., Department of Biology. Dalhousie Univenily, Halifax, Nova Scotia. 
OLSON, DR. JERRY s.. Environmental Scieiicei DhUoii, Oik Ridge Natioait 

Oak Ridge, Tennessee 37830. 
rARKlNSON. DR. DtNNiS, OepaftimnI of Biology, University oi Calgary, Calgary, 
Abartt. Canada. 

fETRUSFwicz. OR KAZiMiERZ, Institute of Eoology.PoUsh Aodamy ofSdeooM, 

Dziekanow Luny near Warsaw, Poland. 
RODIN. DR. L. B., Komtfov Botaflieal Imtitute, USSR Acadamy of Sdencei, Leningnd, 

USSR. 

Rozov. DR. N. N.. Dokuchaev Soil institute, Moscow, USSR. 

SCHINDLER. DR. D. w.. PUieitet Inititute, Ptwhwatw Institute, 501 UnheraUy Cieacent, 

Winnipeg 19, Manitoba. 
SHUGART, OR. HERMAN H.. JR., Environmental Sciences Division, Oak Kidge National 

Uboratory, BuiUiRg 301 7, Oak Ridge, Tennessee 37830. 
soLLiNs, DR p..CoiefeofFociettReflouKet,AR>10,Unhetsi^ofWa4iiiitloii,8n 

Washington 98195. 

TAMM, PROP. CARL OLOF. Department ofpotctt Eodogy, The Royal College of 

Forestry. S I 04 05, Stockholm .^0, Sweden. 
WALKER, DR. RICHARD B., Botany Department AK-IO, University of Washington, 

Seatde, Wiihiqgton 9819S. 
wiELGOL ASKi. DR. P. B., Botmicil Labontoiy, Univeialty of Gilo, Oslo 3, Norwqr. 



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