Short-term responses of riparian salamander populations to wildfire in the Southern Appalachians

Abstract

Wildfire is a natural disturbance within many forest ecosystems and is rapidly becoming more frequent and severe because of the combination of historical fire suppression and climate change. In Southern Appalachian hardwood forests, there is a limited understanding of how salamander populations respond to wildfire, despite their high diversity and abundance in forest ecosystems. We expected populations of lungless, plethodontid salamanders to respond negatively to wildfire and the drier microhabitat conditions in burned habitat. We evaluated the effect of fire on 3 plethodontid salamander species (Blue Ridge two-lined salamander [Eurycea wilderae], Ocoee salamander [Desmognathus ocoee], red-legged salamander [Plethodon shermani]) with different life histories from 2017–2019 following a wildfire in a Southern Appalachian riparian forest in North Carolina, USA. We estimated differences in abundance, frequency of adults in the population, and terrestrial distribution in relation to streams between burned and reference riparian forest sites. Wildfire had negative effects on the abundance of semi-aquatic species, but temporal patterns differed by species. Abundance of the Blue Ridge two-lined salamander was lower in burn sites than reference sites immediately after fire, followed by a gradual convergence towards reference-site densities. Conversely, Ocoee salamanders had a time-lagged response, where we observed significantly lower densities in burn sites relative to reference sites for only 2 years after fire. We did not observe strong responses of red-legged salamander abundance to fire. There were no consistent patterns in how the percentage of adults in reference or burn sites differed over time, suggesting that population responses to burn vary by species. Finally, we observed adults of all species and juveniles of semi-aquatic species farther from streams in burn sites. Our findings suggest plethodontid salamander communities may tolerate riparian wildfires, although longer-term studies are required to understand how long it takes for patterns of population size structure and habitat use to converge with those in unburned reference sites.