New developments in forest modeling: Convergence between applied and theoretical approaches

Additionally to simulations, a mathematical analysis of ecological models could give insights into the system behavior. However, mathematical model analysis has only been performed for simple, abstract models, because models based on biological processes are too complex. Linking simple and detailed approaches could help to obtain mathematically tractable models which are based on physiological and ecological processes. This can be achieved either by extending simpler models with components of complex ones, or by a controlled simplification of complex models. Forest models ranging from models describing processes in organs of individual trees in three-dimensional space to models averaging over all trees of an entire region, are reviewed, categorized by hierarchical level and represented in a general mathematical formulation. Possibilities and approaches of transitions between the approaches, namely linking of approaches and upscaling of individual based models are presented and discussed.