Aggregation of individual trees and patches in forest succession models: Capturing variability with height structured, random, spatial distributions

Individual based, stochastic forest patch models have the potential to real istically describe forest dynamics. However, they are mathematically intran sparent and need long computing times. We simplified such a forest patch mo del by aggregating the individual trees on many patches to height-structure d tree populations with theoretical random dispersions over the whole simul ated forest area. The resulting distribution-based model produced results s imilar to those of the patch model under a wide range of conditions. We con cluded that the height-structured tree dispersion is an adequate population descriptor to capture the stochastic variability in a forest and that the new approach is generally applicable to any patch model. The simplified mod el required only 4.1% of the computing time needed by the patch model. Henc e, this new model type is well-suited for applications where a large number of dynamic forest simulations is required. (C) 1998 Academic Press.