SPATIAL SCALE, PATCHINESS AND POPULATION-DYNAMICS ON LAND

The most striking difference between land and open sea is the greater structural heterogeneity of terrestrial environments. I make a distinction between two principal kinds of patches at two spatial scales, defined by the relative contributions of behaviour and demography to variation in density. At the scale of resource patches, movements of individuals among the patches influence the frequencies of ecological interaction among the mobile individuals and their offspring. Many studies have demonstrated how independently aggregated spatial distributions generally enhance stability of single-species and many-species dynamics. At the scale of habitat patches, assemblages of local populations connected by migration constitute metapopulations. I outline a range of modelling approaches to metapopulation dynamics, including spatially implicit, explicit and realistic models. I describe a novel spatially realistic approach, based on generalized incidence functions, which can be parameterized with data on the pattern of occupancy in a network of habitat patches. This approach allows one to make quantitative predictions about transient dynamics in particular metapopulations.