Modeling Large-Scale Vegetation Dynamics

Abstract

Environmental changes affect vegetation. The dependence of plant cell processes on light, temperature, moisture, and nutrients is the basis for this, but with time the consequences of environmental changes extend to variations in community characteristics including species composition, biomass, leaf-area profiles, and the continental distributions of natural vegetation zones or biomass. In this chapter, we discuss models that are useful in analyzing responses of vegetation to large-scale environmental changes. We emphasize climate, but most concepts and approaches are pertinent to other global changes as well. First, we summarize the natural processes that dictate vegetation dynamics under changing environmental conditions. Models that relate natural vegetation distribution to climate are then described. These can be purely correlative --- based on observed relationships between vegetation and climate, without regard to the mechanisms involved. But to simulate transient responses, we need dynamic models that represent community processes including competition. We summarize a class of such models that are suited to small landscape or patch analysis. We conclude by outlining a scheme for applying these models in large-scale studies, by a Monte Carlo method that samples spatial variability in the environment. 72 refs.