Differential Responses of Two Anuran Species Breeding in Rice Fields to Landscape Composition and Spatial Scale

Rice fields provide important habitats for many endemic and endangered species originally dependent on wetlands as habitat. However, the value of rice fields has rarely been evaluated from a multi-scale perspective. We examined abundance of two frogs, the montane brown frog Rana ornativentris and the forest green tree frog Rhacophorus arboreus, that use rice fields as breeding sites, and explored local and landscape-level factors determining their abundance. To determine appropriate spatial scales influencing abundance, we generated different sized buffer circles around a focal rice field, calculated landscape composition in each buffer, and determined the regression model that best explained frog abundance using Akaike's Information criterion (AIC). The montane brown frog and the forest green tree frog exhibited the lowest AIC at buffer sizes of 300 and 1,000 m, respectively. Both species exhibited a higher abundance at intermediate water depths (7-10 cm). At the landscape-level, the montane brown frog showed highest abundance at intermediate forest cover (50%-60%). Forest green tree frogs showed a monotonic increase with forest cover. Because each species responded somewhat differently to spatial scale and landscape composition, context and species dependent outcomes of local restoration practices are required for particular rice fields to achieve cost-effective results.