290 



WHITTAKER AND LIKENS 



700 





c 

 o 



S 500 



E 



co- 

 co 



< 



CO 



> 



cr 

 Q 



Q 

 Z 

 D 

 O 

 QC 



> 



o 



CD 

 < 



300 



100 



Circles = climax stands 

 Squares = immature stands 

 Biomass (metric ton/ha) = 0.625 x 



productivity (g m - 2y ear 



-250 



D 



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 States; data of Whittaker, 79 Whittaker and Woodwell, 8 2 and unpublished 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 fields. 35 ' 80 On land 



