Local and Landscape Drivers of Pond-Breeding Amphibian Diversity at the Northern Edge of the Mediterranean

Most amphibian species are highly dependent on available aquatic habitats and their surrounding environments. In this study, we determined which factors influence amphibian diversity in a Mediterranean ecosystem characterized by a mosaic of natural areas and traditional land use. We sampled 60 temporary and permanent ponds in northeastern Portugal, determining amphibian species richness and community composition. At local (5-and 50-m buffers) and landscape (500-m buffer) scales, we analyzed the relationship between these measures and environmental factors describing wetland characteristics, surrounding land cover, habitat heterogeneity, and local road density. Both species richness and community composition were mainly influenced by local factors. Species richness was positively correlated with pond hydroperiod, habitat heterogeneity, and scrub cover within 5 m, and negatively correlated with bare ground coverage and road density within 50 m. Coniferous forest was the only landscape variable explaining species richness with a positive association. Hydroperiod was the most important factor determining community composition, along with aquatic vegetation and several land cover variables. Traditional farmland did not adversely impact amphibian diversity, and instead might provide habitat heterogeneity and breeding sites for amphibians. Our results provide practical information for amphibian conservation and habitat management, and support the view that biodiversity can coexist with traditional farming activities. In similar landscapes, efforts to maintain the diversity of amphibian communities should focus on preserving wetlands and local habitats.