Vcmax - leaf nutrient

Currently, we use the leaf N to Vcmax linear relationship (NUE) from Kattge et al. (2009) which does not account for leaf P effects. Leaf P was shown to affect Vcmax, by modulating the Vcmax-leafN relationship (Walker et al. 2014). For tropical PFTs are minimum Vcmax from leafP derived Vcmax and leaf N derived Vcmax (Domingues et al. ) was suggest and applied (Mercado et al. ).

The Domingues et al. () relationship results in ORCHIDEE to Vcmax values for extra-tropical FLUXNET sites which are less realistic than the ones derived from Kattge's NUE.

In SBG output you can find the diagnosed Vcmax from realtionship of Domingues r(VCMAX_DOMNIGUES), Walker (VCMAX_WALKER) and Kattge (VCMAX_KATTGE). The VCMAX_WALKER might be buggy. VCMAX_KATTGE is the actual Vcmax used in the calculation of photosynthesis.