Effects of competition mode on the spatial pattern dynamics of wave regeneration in subalpine tree stands

The effects of competition between individuals (the degree of competitive asymmetry and the intensity of competition; an endogenous biological factor) and the intensity of disturbance (unidirectional prevailing winds in the present paper; an exogenous environmental factor) on the spatial pattern dynamics of wave regeneration in subalpine regions were studied by using a coupled map lattice model (a lattice model with discrete time, discrete space and continuous state) of plant populations. It was shown by simulation that the wave-shaped spatial pattern of regeneration is more likely to emerge under symmetric competition than under asymmetric competition and that the likelihood of emergence increases with the intensity of disturbance. It was already shown both theoretically and by field data analysis that Abies undergoes symmetric competition and that Betula undergoes asymmetric competition. Therefore, a theoretical explanation can be given as to why the wave-shaped spatial pattern occurs in Abies forests but not in Betula forests although both the species occur in subalpine regions. Our theoretical study showed that the interaction between endogenous and exogenous factors determine the spatial pattern dynamics in relation to the regeneration of plant communities.