SIMULATION OF MULTISPECIES TROPICAL FOREST DYNAMICS USING A VERTICALLY AND HORIZONTALLY STRUCTURED MODEL

The mutual interaction of forest growth and light conditions causes ve rtical and horizontal differentiation in the natural forest mosaic. Th e associated physical processes should be represented in simulation mo dels describing long-term forest dynamics. The FORMIX2 (tropical) fore st simulator incorporates the multi-storey canopy layer structure of t he natural tropical forest, the basic processes of gap succession dyna mics and gap interaction by tree fall and seed dispersal, several func tionally different species groups (emergents, main canopy trees, pione ers, woody treelets and forest-floor herbs) and the energy (carbon) ba lance of assimilation, dissimilation, and increment resulting from the differing light conditions for the various canopy layers in the gap-s ize areas of a forest mosaic. The vertically and horizontally structur ed FORMIX2 model produces time-dependent results (average per hectare data) for stem numbers, diameter distributions, basal areas, standing crop and yield, as well as dynamic views of the forest profile and of spatial forest development, as a function of logging method and intens ity and silvicultural treatment. The model has been applied in an expl oratory investigation to compute the long-term development of (a) virg in forest and (b) logged-over forest in Sabah, using prototypical data . The results obtained agree with empirical data.