Amphibians and reptiles respond differently to land use disturbances in western Georgia, USA

Urban and agricultural land uses have caused documented declines in the diversity of many organisms.  However, the responses of stream- and riparian-dwelling amphibians and reptiles to anthropogenic land development are collectively understudied, particularly in the Piedmont ecoregion of the United States.  We surveyed watersheds in four land-use categories (reference, pasture, developing, and urban) for amphibian and reptile species richness over a two-year period.  Total herpetofauna species richness was equivalent among all watershed types, but amphibians and reptiles responded differently to urbanization when analyzed separately.  Urban watersheds had significantly fewer amphibian species than all other watershed types, but in these same watersheds significantly more reptile species were detected.  We also found that local, riparian-scale habitat differences were strongly correlated with species composition differences between pasture and developing watersheds.  While the difference in species composition between pasture and developing sites may have multiple, species-specific explanations, the dramatic differences between amphibian and reptile species richness in urban watersheds suggest broad trends that may be important to conservation planning.  We conclude that amphibians and reptiles, despite some physiological similarities, are not equivalent for monitoring purposes, as some researchers have implied.  Additionally, we suggest that the developing watersheds in our study are of high conservation priority because they exhibit high species richness and are simultaneously under the greatest threat of future land development.