Biodiversity conservation adaptation to climate change: Protecting the actors or the stage

To be able to protect biodiversity in coming decades, conservation strategies need to consider what sites will be important for species not just today but also in the future. Different methods have been proposed to identify places that will be important for species in the future. Two of the most frequently used methods, ecological niche modeling and climate resilience, have distinct aims. The former focuses on identifying the suitable environmental conditions for species, thus protecting the "actor, " namely, the species, whereas the latter seeks to safeguard the "stage, " or the landscape in which species occur. We used the two methods to identify climate refugia for 258 forest vertebrates under short- and long-term climatic changes in a biodiversity hotspot, the Appalachian ecoregion of the United States. We also evaluated the spatial congruence of the two approaches for a possible conservation application, that of protecting 30% of the Appalachian region, in line with recent national and international policy recommendations. We detected weak positive correlations between resilience scores and baseline vertebrate richness, estimated with ecological niche models for historical (baseline) climatic conditions. The correlations were stronger for amphibians and mammals than for birds and reptiles. Under climate change scenarios, the correlations between estimated vertebrate richness and resilience were also weakly positive; a positive correlation was detected only for amphibians. Locations with estimated future gain of suitable climatic conditions for vertebrates showed low correlation with resilience. Overall, our results indicate that climate resilience and ecological niche modeling approaches capture different characteristics of projected distributional changes of Appalachian vertebrates. A climate resilience (the stage) approach could be more effective in safeguarding species with low dispersal abilities, whereas an ecological niche modeling (the actor) approach could be more suitable for species with long-distance dispersal capacity because they may be more broadly impacted by climate and less sensitive to geophysical features captured by a climate resilience approach.