FORMOSAIC: an individual-based spatially explicit model for simulating forest dynamics in landscape mosaics

A forest is embedded in heterogeneous landscape mosaics and interacts with the surrounding environment through processes such as seed dispersal. Previous forest models, however, have either ignored such interactions or made unrealistic assumptions. We developed a landscape model (FORMOSAIC) that explicitly considers not only the dynamics of a focal forest but also ecological impacts of adjacent areas on the focal forest. FORMOSAIC is hierarchically structured, spatially explicit, multi-scale, stochastic, and individual-based. It integrates information of tree position, regeneration, growth, death, spatial interaction, and environmental factors. Data for parameterizing FORMOSAIC were mainly from a 50 ha permanent study plot in the Pasoh forest reserve (Malaysia), which contained over 800 tree species and more than 330 000 trees with diameter at breast height (dbh) ]1.0 cm. Model simulation results agreed well with independent field census data in terms of species richness, species composition, tree abundance, and basal area at two spatial scales. Sensitivity analysis indicated that minimum harvest size was the most sensitive parameter. Species richness was particularly sensitive to the duration of seed immigration from species-rich surrounding forests. For tree abundance and basal area, the second most sensitive parameters varied at two spatial scales. Through uncertainty analysis we found that many parameters had scale-dependent and non-linear relationships with species richness, tree abundance, and basal area. There also existed significant interactive effects between parameters. The model could be a useful tool for addressing important issues such as fragmentation and deforestation in forest management for species diversity and timber production from a landscape perspective. © 1998 Elsevier Science B.V. All rights reserved.