The relative importance of aquatic and terrestrial variables for frogs in an urbanizing landscape: Key insights for sustainable urban development

Abstract

Globally, urbanization threatens ∼950 amphibian species with extinction. Yet a lack of knowledge onthe factors influencing common and infrequently encountered species in landscapes that are underincreasing pressure from urban development is limiting effective conservation. We examined the rel-ative importance of aquatic variables (pond) and terrestrial variables (at three spatial scales: 10 m, 100 mand 1 km), for commonly and infrequently encountered frogs in an urbanizing forested landscape insoutheastern Australia. Species richness and the occurrence of four common species were influencedby the aquatic environment (water body size, aquatic vegetation). Species richness also decreased withincreasing urbanization within 1 km. This trend was driven by a strong decrease in richness of infre-quently encountered species with increasing road length within 1 km from breeding ponds. Richness ofinfrequently encountered species also decreased with a reduction in forest cover within 10 m to 1 kmfrom breeding ponds. Our findings suggest that frog conservation in urbanizing landscapes requires amix of strategies across different spatial scales. Maintaining or re-establishing common frogs in urban-izing forested landscapes is likely to be achieved by providing ponds with suitable habitat. However, toconserve several frog species that are sensitive to forest loss and urbanization, breeding habitats need tobe maintained within a network of large forest reserves.