Complex patch geometries maximize species richness at the expense of forest specialists

Abstract

Habitat loss and fragmentation are the greatest threats to reptiles and amphibians (herpetofauna) around the globe, but especially in the Neotropics where high diversity and ongoing land-use change coincide. Persistence of biodiversity in fragmented systems relies both on characteristics of habitat patches, and on the permeability of the landscape that separates the patches (the “matrix”). We sought to understand: (a) how the herpetofauna community differs between forest reserves, patches, corridors, and matrices, and (b) the landscape characteristics that increase suitability of a habitat patch. We conducted herpetofauna surveys in patches, corridors, matrices, and preserves (54 total sites) in a fragmented landscape in Costa Rica for three seasons. We recorded 1663 individuals of 52 species. We found that the herpetofauna community differed, and had lower richness and abundance, in the matrix compared to the other three habitat types. Patches and corridors supported a similar community to the forest preserves, demonstrating the conservation value of small forest remnants. Water body presence was an important predictor of richness and abundance in both patches and matrices. While total richness increased in patches with more edge, this was driven by the response of generalist species, whereas the prime indicator species of forest preserves decreased in patches with complex shapes. The differing response to landscape characteristics between specialist and generalist species demonstrates the importance of considering specific taxa when setting conservation goals, rather than using richness measures alone. Our findings can help guide preservation of forest fragments to optimize biodiversity conservation in mixed forest-pastoral landscapes. Abstract in Spanish is available with online material.