Simulation of the Structural Development of Warm-Temperate Rain Forest Stands

The change in all-sized dbh distribution with stand age was simulated using data from secondary stands of different ages after clear-felling in warm-temperate rain forests in Yakushima Island, southern Japan. The cumulative basal area [cm2 m−2] of all trees larger than a given dbh x [cm] was used as an index of onesided density effect, which primarily regulates the growth rate and mortality of the tree at x. The relative growth rate in dbh was expressed by a negative linear function of both the cumulative basal area and logarithmic dbh, irrespective of stand age. Mortality was found to be positively related to the cumulative basal area. From these empirical relations, the change in dbh distribution during the course not only of stand development after clear-felling, but also of gap regeneration within primary forests, was successfully simulated using the continuity equation, eliminating ‘stand age factors’ from the model. Results of the simulation satisfied the —3/2 power law of self-thinning.