CARBON IN THE BIOTA 287 



are 1.0 to 3 for many grasslands, 3 to 10 for desert scrub and shrublands, 10 to 

 30 for woodlands and young forests, and 30 to 50 in mature forests. 79 ' 80 For a 

 given level of productivity, the biomass-accumulation ratio and biomass are 

 strongly affected by the age of a young community, or the mean longevity of 

 the dominants of a mature one. Figure 4 shows the relation for some of our 

 forest data; a comparable plot for grasslands would give a much lower slope, 

 expressing lower biomass-accumulation ratios. Marine and terrestrial com- 

 munities are different realms of correlation of biomass and production. Whereas 

 on land with vascular plants dominant, biomass-accumulation ratios range from 

 1 to 50 or more; in plankton communities with their short-lived algae, these 

 ratios are small fractions of 1, probably one-twentieth to one-fiftieth. From this 

 contrast results the biomass disparity of land and sea as shown in Table 1, 

 column 8. Land production may be about twice that of the seas, but land plant 

 biomass appears to be 600 times that of the seas, and more than 1000 times that 

 of all the phytoplankton of the oceans. 



HISTORY AND THE RELATIVE PRODUCTIVITY OF LAND AND SEA 



Table 2 summarizes estimates of world primary productivity (compare 

 Ref. 34). We think these of interest in two connections: first, the reliability of 

 the estimates, and, second, the relation of land and sea production. 



The wide contrasts in early estimates would be expected. Liebig's 32 was a 

 casual estimate of what world production would be if the world's surface were 

 covered by a moderately productive meadow [500 g (dry matter) nv 2 year -1 ] . 

 He was not too far from current estimates since the weighted mean production 

 of the world is, we think, that of a dry grassland or semidesert (320 g m" 2 

 year ). The Ebermayer 1 7 and Schroeder 67 estimates are based on less happy 

 choices from too-limited data, and these influenced the low estimates of Fogg, 24 

 Muller, and Lehninger. 31 Early estimates of marine production, based on 

 potential rather than actual production, 53 ' 62 seem much too high. Bowen's 9 

 estimates use values from an article by Westlake 7 that is, for this purpose, 

 biased by selection toward maximum values. We believe the estimate of 

 Bazilevich, Rodin, and Rozov 6 also was influenced by preference for high values. 

 The remaining recent estimates are those of Whittaker and Likens, 80 ' 81 

 SCEP, ' Lieth, Golley, 2: and we suggest the combination of the marine 

 estimate of Koblentz-Mishke et al. 29 with Olson's 47 terrestrial estimate. These 

 five values give an average of 161 X 10 9 metric tons (dry matter)/year with a 

 coefficient of variation of 5.8%. This seems a reasonable convergence and 

 acceptable dispersion, considering the nature of the effort; but it should be 

 noted that Golley 2 :> used our mean productivity values, and some of the other 

 estimates are not fully independent 



A point that has come into focus since the early estimates is the disparity of 

 productivity on land and sea. If temperature and light are largely equivalent for 

 land and sea, and water and nutrients the key determinants of production for 



