An argument for the use of two-layer SVAT schemes to simulate terrestrial carbon dioxide fluxes

An order-of-magnitude argument shows that the different surface temperature s of soil and sparse vegetation affect carbon assimilation and soil respira tion significantly. However, regulation of assimilation through associated modulation of in-canopy carbon dioxide levels is weak. It is shown that for many vegetation types, the use of a two-layer represen tation of vegetation is essential to predict, accurately, terrestrial carbo n fluxes, primarily through allowing different surface energy balances.