Fig. 4
Carbon allocation schemes incorporated in most terrestrial ecosystem models (TEMs). a TEMs that include an “NPP allocation scheme” (Table 1) simulate organ growth as a daily fraction (termed the “allocation coefficient”, αi, dimensionless) of NPP (net primary production). The NPP is the difference between GPP (gross primary production) and Ra (autotrophic respiration) and can be regarded as the carbon supply available for growth. Growth is thus driven by the carbon source. b TEMs that include a “labile pool allocation scheme” (Table 1) do not rely directly on NPP to simulate organ growth. Rather, the growth of each organ is a flux (βi, in grams of carbon per day), representing the sink force of each organ