Influence of breeding habitat characteristics and landscape heterogeneity on anuran species richness and abundance in urban parks of Shanghai, China

Urbanization has caused a significant decline in amphibians worldwide due to habitat loss, fragmentation, and degradation of habitat quality. Accordingly, parks have become islands, or habitat fragments, for amphibians in highly urbanized areas. Understanding the habitat use pattern of amphibians in fragmented urban environments is essential for biodiversity conservation in urban ecosystems. Several environmental features may affect anuran communities in urban parks, including the characteristics of fragmentation, landscape heterogeneity, breeding habitat, and human disturbance. In particular, it is unclear whether a larger habitat area could lead to higher anuran species richness (species-area relationship) in urban parks. The aim of this study was to examine whether the species-area relationship is relevant for anurans in urban parks, and to determine the environmental characteristics that likely influence anuran communities. We used a visual encounter method to survey anuran communities (species richness and abundance) in 16 parks located in highly urbanized areas of Shanghai, China. Fragmentation characteristics included fragment size and shape index. Landscape heterogeneity was measured as compositional heterogeneity (using the Shannon diversity index of wetland types) and configurational heterogeneity (using edge density of different land use types). We found that compositional and configurational heterogeneity had significant positive effects on anuran species richness and relative abundance, respectively, in the urban parks. We also found that high edge density along streams benefited anuran abundance. However, there was no significant relationship between fragment size and anuran communities, and the abundances of Pelophylax plancyi and P. nigromaculata were negatively associated with the edge density of large ponds and roads. Our results suggest the importance of landscape structure in urban parks for sustaining anuran persistence. In addition, diverse breeding habitats and landscape heterogeneity should be considered positive indicators of anuran biodiversity conservation in fragmented urban habitats.