A pair-approximation model for spatial patterns in tree populations with asymmetrical resource competition

Abstract

A pair-approximation model for the spatial dynamics of a height-structured tree population is defined on a regular lattice where each site can be in one of three states: empty (gap site), 10 occupied by an immature tree, and occupied by a mature tree. The nonlinearities are associated with resource competition effects of mature trees on immature ones (asymmetric competition) affecting the mortality of the latter but not their growth. The survival-extinction transition of the forest is expressed; the early dynamics of colonization are described in terms of local densities. Predictions of the pair approximation model are compared with results 15 from numerical simulations of cellular automata.