TOWARD AN INTEGRATION OF LANDSCAPE AND FOOD-WEB ECOLOGY - THE DYNAMICS OF SPATIALLY SUBSIDIZED FOOD WEBS

We focus on the implications of movement, landscape variables, and spa tial heterogeneity for food web dynamics. Movements of nutrients, detr itus, prey, and consumers among habitats are ubiquitous in diverse bio mes and can strongly influence population, consumer-resource, food web , and community dynamics. Nutrient and detrital subsidies usually incr ease primary and secondary productivity, both directly and indirectly. Prey subsidies, by movement of either prey or predators, usually enha nce predator abundance beyond what local resources can support. Top-do wn effects occur when spatially subsidized consumers affect local reso urces by suppressing key resources and occasionally by initiating trop hic cascades. Effects on community dynamics vary with the relative amo unt of input, the trophic roles of the mobile and recipient entities, and the local food web structure. Landscape variables such as the peri meter/area ratio of the focal habitat, permeability of habitat boundar ies, and relative productivity of trophically connected habitats affec t the degree and importance of spatial subsidization.