Random Frogs: Using future climate and land-use scenarios to predict amphibian distribution change in the Upper Missouri River Basin

Abstract

Context Climate change and anthropogenic stressors have contributed to rapid declines in biodiversity worldwide, particularly for amphibians. Amphibians play important ecological roles, yet little is known about how distribution hotspots may change or the factors influencing distribution patterns in the North American Great Plains. Objectives Ecological niche models improve understanding of biotic and abiotic factors associated with species' distributions and can highlight potential threats to species conservation. Here, we identify important predictors of amphibian distributions and predict how land use and climate change may alter distributions in the Upper Missouri River Basin. Methods We used publicly available occurrence data, 16 environmental and climatic predictors, and the machine-learning algorithm, Random Forests, to create spatially-explicit distribution models for eight amphibian species. Models were scored to current conditions (2005) and two future climate-change/land-use scenarios to predict changes in amphibian distributions for 2060. Results Models were highly accurate and revealed more pronounced distributional changes under the intensive RCP8.5/CONUS A2 scenario compared to the moderate RCP6.0/CONUS B2 scenario. Both scenarios predicted gains for most southeastern species (i.e., Blanchard’s cricket frogs, Plains leopard frogs, Woodhouse’s toads, and Great Plains toads) and declines for all western montane species. Overall, distribution changes were most influenced by climatic and geographic predictors, (e.g., summer temperature, precipitation, and elevation), and geography, versus anthropogenic land-use variables. Conclusions Changes in occurrence area varied by species and geography, however, high-elevation western species were more negatively impacted. Our distribution models provide a framework for future conservation efforts aiding the persistence of amphibian species across a warming, agriculturally dominated landscape.