Tree mortality in LPJmL results from light competition, low growth efficiency, heat stress and fire. Mortality from light competition occurs as a reduction of FPC for PFTs when a maximum value of 0.95 is exceeded. Mortality from low growth efficiency is determined from the ratio between NPP and LAI and inversely related to growth efficiency. Mortality from heat stress occurs, when a temperature threshold is exceeded. Fire mortality is described in detail in the chapter “spitfire”.

Mortality results in a loss of tree individuals thus reducing the biomass of a PFT. The killed biomass is transferred to the litter pool, and with fire mortality, to the atmosphere.

For a detailed description see Sitch et al. 2003

In src/tree/mortality_tree.c :
Growth efficiency mortality:

if(bm_δ<0)
bm_δ=0

Mortality from heat stress:
if(mtemp_max>pft~~par~~>twmax) {
heatstress=tree->gddtw/ramp_gddtw; if(heatstress>1)
heatstress=1;
mort+=heatstress;
}


Mortality from light competition: in src/lpj/light.c