Species diversity and the scale of the landscape mosaic: do scales of movement and patch size affect diversity?

We use a combination of a model and empirical data to examine the relationship between the scale of the landscape mosaic and individual movement patterns on the measurement of local butterfly species diversity. In landscapes where patch sizes are smaller, the type of patch adjacent to the patch surveyed can influence both local species richness and incidence. In landscapes composed of larger patches, adjacency has no effect on species richness or incidence. We hypothesize that the mechanism for species enrichment is the potential for movement of individuals between habitats, resulting in either (a) spillover of species from the higher-diversity patches into other habitats, or (b) habitat sampling by species that benefit from the resources in adjacent patches. In order to determine whether landscape configuration alone can account for the observed patterns of diversity, we employ a simulation model. Simulation results suggest that both specialist and generalist butterflies can sample a much more diverse array of habitat types in a more fine-grained landscape. (C) 2001 Elsevier Science Ltd. All rights reserved.