A Generalized Poisson Model to Estimate Inter-plant Competition for Light

A new method is proposed to compute the functional effects of competition for light in plant populations. It is based on the estimation of exposed green leaf area for each individual. For this purpose, each individual in the stand is assigned a disk-shaped zone S^P representing its assumed crown projection and competitive neighbours are defined as plants having overlapping disks. We combine the foliage distribution functions of neighbours to compute the probabilities of dominance and thus the exposed leaf area for each plant. The computation is fully detailed in the case of uniform distributions (Poisson model). In functional- structural models of plant growth, the exposed leaf area thus obtained can be used to compute biomass production. The method is applied to the GREENLAB model and we present simulation results illustrating the effects of density.