SUSTAINABILITY OF AN ISOLATED BEECH DWARF BAMBOO STAND - ANALYSIS OF FOREST DYNAMICS WITH INDIVIDUAL BASED MODEL

The beech Fagus crenata forest on Mt. Jippo in southwestern Japan has been reduced to small fragments by past human activity. The forest flo or is covered by dense dwarf-bamboo, Sasa, which is an inhibitor of be ech regeneration. One of the ecological features of Sasa is that it wi thers synchronously over a large area once every several decades. An i ndividual based model (IBM) was developed to evaluate the sustainabili ty of such a fragmented beech stand considering the dynamics of Sasa. The model has three submodels for beech individuals: growth, mortality and seed production. The parameters of these submodels are estimated from field measurements. By using this model together with Sasa dynami cs, we can evaluate the adverse effect of Sasa on enhancing the risk o f extinction of a single fragmented beech stand over 500 years. The re sults obtained by Monte Carlo simulations are: (1) Sasa has a strong i mpact on the sustainability of a isolated beech stand; (2) the effects of two parameters for Sasa life history, the longevity and the recove ry time, can be statistically separated from each other; and (3) the p robability of extinction of a beech stand depends much more strongly o n the parameters of beech mortality than those of growth rate. (C) 199 8 Elsevier Science B.V. All rights reserved.