294 WHITTAKER AND LIKENS 



estimates given by Kovda 30 seem to us far too high. In most terrestrial 

 communities, animal biomass is concentrated in small and short-lived inverte- 

 brates rather than the more conspicuous vertebrates; earthworms are apparently 

 the most massive animal group in forests (Refs. 18, 46, 52, 84). Vertebrate 

 biomass may exceed invertebrate biomass in grasslands supporting populations 

 of large grazing mammals, 36 and Riley 55 suggests that in the sea biomass may 

 be higher in longer lived animals of higher trophic levels than in the 

 zooplankton. 



Our estimates suggest that (because of higher consumption percentages in 

 the sea) the contrast in total production between land and sea is reversed, going 

 up the trophic pyramid from producers to primary consumers. About 

 three-quarters of world animal production (excluding man and domestic- 

 animals) may be in the sea. Our total animal-biomass estimates are closely similar 

 for the continents and the seas, although animal biomass may be only one 

 two-thousandth of plant biomass on land, but one-quarter of plant biomass in 

 the seas (in which mass of zooplankton at times exceeds that of phytoplankton). 

 Since columns 5 and 7 (Table 3) are estimated from independent sources, the 

 relation between them as affected by size and longevity of animals is potentially 

 of interest. We attach no significance to the ratios of animal biomass to animal 

 production as estimated for particular ecosystem types. The averages of these 

 ratios (1.23 on land, 0.33 in the sea) suggest, however-. (1) The predominance in 

 community function of small animals with life-spans of a year or less. On both 

 land and sea the greater part of animal biomass appears to be in smaller and 

 more obscure organisms — zooplankton rather than fish, and arthropods and soil 

 animals rather than birds and mammals. (2) Marine zooplankton have shorter 

 lives and more rapid mass turnover than terrestrial invertebrates. Table 1 does 

 not include production, consumption, and biomass of man and domestic 

 animals. Borgstrom 8 estimated the world biomass of livestock animals as 

 925 X 10 6 metric tons liveweight, compared with 180 X 10 6 metric tons for 

 man himself (in 1960). These values, converted to carbon for the population of 

 1970, are about 120 X 10 6 metric tons C in livestock and 23.6 X 10 6 metric- 

 tons C in man. 



We have not presumed to estimate reducer or saprobe (bacterial and fungal) 

 production and mass for ecosystem types from the scanty material available. It is 

 reasonable, however, to treat the biosphere as approaching (apart from the 

 effects of man) a steady state of the whole in which total respiration of all 

 heterotrophic organisms essentially equals total net primary production. Given 

 this equality, total reducer assimilation should approximately equal net primary 

 production minus animal assimilation (column 4, in Table 1, minus column 5, in 

 Table 3, and animal respiration). (Complications affecting this relation include 

 use of animal tissues and excreta by reducers, and consumption of dead plant 

 tissues by animals, some of which use as food bacteria and fungi of decay rather 

 than the plant tissues themselves. We have no basis on which to evaluate these 

 complex food-chain relations and the role of mycorrhiza in terrestrial com- 



