ABOUT MODELS OF THE DYNAMICS OF HETEROGEN EOUS FOREST COMMUNITIES - STRUCTURES, DEMOGRAPHIC-PROCESSES AND REGULATORY MECHANISMS

This paper reviews several methods and models that are used for descri bing and simulating the dynamics of heterogeneous forests of which den se rain forests constitute an emblematic illustration. The emphasis is put on problems related (i) to the definition, delineation and charac terization of such stands which exhibit highly diversified vertical, h orizontal and size structures, (ii) to the interaction between demogra phic processes (growth, regeneration and mortality), and (iii) to the spatial constraints (e.g. competition, density-dependence) which regul ate biological mechanisms. The existence and properties of the followi ng types of models are briefly reminded: stand yield models based on a global mass budget; discrete-time demographic models for stage-struct ured populations, whether including or not density-dependence; gap mod els based on a description of the vertical stratification of the fores t; mosaic models, whether including or not spatial interactions betwee n the units of the mosaic; individual growth models based on-a descrip tion of tree-to-tree competition.