The Emerging Role of Patchiness in Conservation Biology

Summary

Ecology provides the scientific foundations of conservation biology. Two ecological views of patchiness are particularly relevant to placing conservation issues in a spatial context. Metapopulation models consider the dynamics of populations in patchy environments, especially metapopulation persistence in the face of local extinctions. Several conditions underlie such persistence, and conservation biologists should determine whether these conditions are likely to hold before applying metapopulation theory to particular situations. Landscape ecology emphasizes the structure of spatial mosaics, drawing attention to the effects of variations in patch quality, boundary influences, patch surroundings, and connectivity among patches. The interaction of the spatial structure of the mosaic with the responses of organisms to that structure determines the scale and spatial patterns of ecological patterns and processes.

Whether these complex features of patchiness must always be considered depends on the questions asked, the level of resolution desired, and the spatial patterns and dynamics themselves. Changes in spatial patterns, such as those accompanying habitat fragmentation, may have threshold effects on populations. Knowing when the spatial arrangement of a mosaic is more important than the amount of habitat present requires an understanding of such thresholds, which may be strongly influenced by the movement of organisms. To overcome the traditional focus in conservation biology on simple patch-matrix or island-mainland conceptualizations of patchiness, greater attention must be given to complex landscape mosaics and their effects. Progress in this area requires better landscape theory and better empirical information on how organisms move and scale environmental patchiness.