. Carbon and the biosphere; proceedings of the 24th Brookhaven symposium in biology, Upton, , May 16-18, 1972. Carbon cycle (Biogeochemistry). 290 WHITTAKER AND LIKENS 700 c o S 500 E co- co cr Q Q Z D O QC > o CD < 300 100 Circles = climax stands Squares = immature stands Biomass (metric ton/ha) = x productivity (g m-2year -250. D 0 200 600 1000 1400 1800 ABOVEGROUND NET ANNUAL PRIMARY PRODUCTION, g (dry matter) m"2 year"1 Fig. 4 Biomass vs. productivity in forest samples from the temperate United States; data of Whittaker,79 Whittaker and Woodwell,8 2 and unpublishe
. Carbon and the biosphere; proceedings of the 24th Brookhaven symposium in biology, Upton, , May 16-18, 1972. Carbon cycle (Biogeochemistry). 290 WHITTAKER AND LIKENS 700 c o S 500 E co- co cr Q Q Z D O QC > o CD < 300 100 Circles = climax stands Squares = immature stands Biomass (metric ton/ha) = x productivity (g m-2year -250. D 0 200 600 1000 1400 1800 ABOVEGROUND NET ANNUAL PRIMARY PRODUCTION, g (dry matter) m"2 year"1 Fig. 4 Biomass vs. productivity in forest samples from the temperate United States; data of Whittaker,79 Whittaker and Woodwell,8 2 and unpublished samples. Samples in the upper part of the oblique band are old-growth climax forests; those in the lower part of the band are climax or near climax, although some are affected by disturbance; those below the band and represented by squares are young and clearly immature forests. The low range of productivity, 200 to 600 g m 2 year ' , represents environments marginal for forest growth; the samples in this range are woodlands of small trees in open growth, rather than true forests. massive structure accumulating nutrients into plant tissue and tending, by partly closed cycles between soil and plant tissue, to hold these nutrients against loss. The short-lived phytoplankton has no such means for the long-term accumula- tion and conservation of its nutrients. The forest has evolved a degree of biological control of nutrient availability; for the phytoplankton, physical processes such as turbulence more directly govern nutrient availability. The critical determinants of production are thus moisture, nutrients, and temperature, with very different weightings of these for land and sea. The very highest productivities are in communities combining abundant water with moderate or high temperatures and continuing nutrient replenishment, such as some floodplain forests and salt marshes, coral reefs and kelp forests, certain tropical lakes and rivers, and fertilized rice and sugar cane f
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