Patch characteristics and landscape context as predictors of species presence and abundance: A review

An increasing proportion of ecological studies examine landscape effects on the phenomena they address. We reviewed studies which simultaneously consi dered landscape-scale and patch-scale effects in order to answer the follow ing question: does' the inclusion of landscape characteristics as explanato ry variables increase our ability to predict species presence and abundance when local (i.e., habitat patch) conditions are known? The 61 studies sele cted cover a wide array of taxa, landscape types, and explanatory variables , but many (36%) focused on avian communities in forests fragmented by agri culture. Patch-scale variables (e.g., habitat characteristics) had a signif icant effect on invertebrates, amphibians, reptiles, birds, and mammals in all landscape types. Landscape-scale characteristics (e.g., area of suitabl e habitat within a certain radius of a patch) also were significant predict ors of species presence and abundance for vertebrates, but not for the majo rity of invertebrates in the studies we reviewed. Thus, our results indicat e that both patch and landscape characteristics should be included in model s investigating the distribution and abundance of animals, at least for ver tebrates. However, distinguishing between local (or patch) and landscape sc ales for particular taxa is often problematic. Analyzing movements of indiv iduals and their influence on larger-scale population dynamics could potent ially solve this dilemma, but other approaches, such as the analysis of con text effects using nested sampling grids covering several different spatial scales may represent a more practical alternative. Results from this revie w suggest that the inclusion of landscape characteristics will enhance cons ervation strategies if the landscape scale is properly defined with respect to the taxon or taxa under investigation.