CARBON IN THE BIOTA 



ROBERT H. WHITTAKER and GENE E. LIKENS 



Ecology and Systematics, Cornell University, Ithaca, New York 



ABSTRACT 



Recent estimates of the net primary production of the biosphere converge on a value of 

 about 160 x 10 9 metric tons (dry matter)/year (73 x 10 9 tons C), with values for land 

 and sea production of 105 and 55 x 10 9 metric tons/year, respectively. Gross primary 

 production should be about twice the net primary production for the biosphere as a 

 whole. The energy equivalent of net primary production for the world is 7.0 x 10 1 7 

 kcal/year, implying an efficiency (of net primary production relative to incident sunlight in 

 the visible range) of 0.25%. Biomass for the world in 1950 is estimated as 1820 x 10 9 metric 

 tons (dry matter) ( 829 x 10 9 metric tons C) very strongly concentrated [all but 3.9 x 10 9 

 metric tons (dry matter)] on land and especially in forests. Preliminary estimates suggest 

 that herbivorous animals harvest, per year, 7.2 x 10 9 metric tons (7%) land net 

 production and 20 x 10 9 metric tons (37%) marine net production to support animal dry 

 biomasses of 6.8 x 10 9 metric tons on land and 2.5 x 10 9 metric tons in the sea. Man's 

 harvest from the land (primarily about 9.5 x 10 8 metric tons cereals) continues to increase. 

 World biomass is decreasing, however, particularly by the cutting of old-growth forests; and 

 decrease in world productivity from biosphere toxication rriust now be expected. 



As carbon is central to the chemistry of life, so the carbon chemistry of the 

 biosphere is central to biogeochemistry. In this paper we shall characterize the 

 biosphere, the living film of the earth, in terms of its carbon content and major 

 single function, productivity. For this purpose we summarize the best available 

 estimates of the magnitudes of total organic matter (biomass) in this film and 

 the annual rate at which it is renewed (net productivity). We offer preliminary 

 estimates of animal, as well as plant, productivity and biomass. 



Serious questions exist about the adequacy of data for these estimates. The 

 magnitude of the world's productivity and biomass can, however, be estimated 

 in two ways: either by stratifying the biosphere into ecosystem types and 

 estimating mean and total values for each of these or by modeling the effects of 

 environmental factors on production and biomass and integrating the results of 



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