A modified 3D-patch model for spatially explicit simulation of vegetation composition in heterogeneous landscapes

Based on a comprehensive review of gap models (patch models sensu Shugart) the newly developed model PICUS v1.2 is described. Proceeding from the fact that most existing patch models have proven to generate reliable results w ith respect to species compositions at regional scales, PICUS v1.2. is inte nded to provide spatially explicit site-specific decision support to forest resource managers regarding long-term vegetation development in heterogene ous alpine landscapes. The model is based on a 3D-core structure which allo ws the spatially explicit simultaneous simulation of several hectares of mu ltiple species forests. Special emphasis is given to (i) the implementation of a light model for both direct and diffuse radiation, (ii) to the modifi cation of the temperature and soil moisture response functions, which have been parameterised based on the combined network of large-scale forest inve ntory data and meteorological data, and (iii) the development of a fuzzy lo gic control unit to model the effect of site nutrient status on vegetation development. As a first test PICUS v1.2 is applied to simulate equilibrium species composition spatially explicit in heterogeneous alpine landscapes a t sample plots of the Austrian Forest Soil Survey along a transect through the Eastern Alps. (C) 2001 Elsevier Science B.V. All rights reserved.