Wildfire is an increasingly common disturbance in forested landscapes that can drastically alter local habitats. Under current climate change predictions, wildfires are likely to become more frequent and severe. In regions and ecosystems that have historically infrequent fire return intervals, there is little known about how organisms will respond to the more severe and frequent wildfires predicted under climate change. In the southern Appalachian Mountains, USA, fire has been suppressed and severe burns are historically uncommon. This region boasts immense biodiversity and is considered a biological hot spot for diversity in the salamander family Plethodontidae. These species rely upon cool, moist microclimates that may be impacted more by severe fire than by low-intensity wild or prescribed fire. In 2016, the Chimney Tops Two wildfire burned >6000 ha of Great Smoky Mountains National Park, USA, and left a mosaic of burn severity across the landscape. This presented an opportunity to examine how five plethodontid salamander species respond to and recover from a range of burn severity. Even though the landscape had been recovering for 5 yr at the time of study, populations of Plethodon jordani, Plethodon glutinosus spp., Desmognathus wrighti, Desmognathus imitator, and Eurycea wilderae within the burn boundary had lower abundance than those in unburned habitat. In addition, there was a trend of even lower abundances in more severely burned habitat. Evidence of recovery, as indicated by a relationship between population abundance and distance from the burn boundary, was only present for D. imitator. Finally, body size distributions were different between burned and unburned sites for three of the five species and individuals were larger, on average, in burned sites. This work provides insights into how terrestrial salamander populations may respond to the more severe and frequent wildfires predicted under climate change for the southern Appalachian Mountains region.

Space-use and demographic processes are critical to the persistence of populations across space and time. Despite their importance, estimates of these processes are often derived from a limited number of populations spanning broad habitat or environmental gradients. With increasing appreciation of the role fine-scale environmental variation in microgeographic adaptation, there is a need and value to assessing within-site variation in space-use and demographic patterns. In this study, we analyze 3 years of spatial capture-recapture data on the Eastern Red-backed Salamander collected from a mixed-use deciduous forest site in central Ohio, USA. Study plots were situated in both a mature forest stand and successional forest stand separated by < 100-m distance. Our results showed that salamander density was reduced on successional plots, which corresponded with greater distance between nearest neighbors, less overlap in core use areas, greater space-use, and greater shifts in activity centers when compared to salamanders occupying the mature habitat. By contrast, individual growth rates of salamanders occupying the successional forest were significantly greater than salamanders in the mature forest. These estimates result in successional plot salamanders reaching maturity more than 1 year earlier than salamanders on the mature forest plots and increasing their estimated lifetime fecundity by as much as 43%. The patterns we observed in space-use and individual growth are likely the result of density-dependent processes, potentially reflecting differences in resource availability or quality. Our study highlights how fine-scale, within-site variation can shape population demographics. As research into the demographic and population consequences of climate change and habitat loss and alteration continue, future research should take care to acknowledge the role that fine-scale variation may play, especially for abiotically sensitive organisms with limited vagility.

This file contains everything needed to run analysis with data scrubbed of exact locations to protect sensitive species. Best paired with RStudio and access through the Project File.

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.

Accurately predicting localized weather and abiotic conditions under forested cover like temperature, relative humidity, soil moisture, and soil temperature at fine spatial temporal scales at any point on earth would be revolutionary in ecology. Recent advances in mechanistic weather downscaling and the development of an R package, microclimc , have made these tools available to the research community. In this study we apply this new model at the locations of two long-term, high-resolution weather stations run by the USGS to understand how well the model can predict multiple abiotic variables. We found that predicted air temperature and soil temperature at a depth of 15 cm were highly correlated with measured values. while relative humidity and soil moisture were not. Additionally, we saw that seasonal trends in error are present, and the most accurate predictions occurred during the summer (May–June). We believe that a worthy endeavor would examine the effects that different parameter tunings have on the accuracy and stability of the models and that there is great potential for mechanistic weather downscaling.

Urban expansion is creating environmental stressors through land use change, habitat fragmentation, and habitat loss. These stressors, along with a host of others, are driving precipitous declines in vertebrate taxa around the world. Amphibians, often requiring a narrow range of environmental conditions, can be especially susceptible to the stressors of environmental change. Despite habitat loss and degradation, some amphibian species continue to persist in altered urban landscapes. The red-backed salamander (Plethodon cinereus) is one such- species and in this study, we assess how habitat patch size affects population density and genetic diversity of salamander populations in and around an urban center in Ohio, United States. Further, we examined patterns of genetic differentiation and landscape connectivity to understand gene flow between populations and tested for historic demographic bottleneck effects. Populations were sampled from 9 urban forest patches ranging in size from less than 1 ha to approximately 250 ha. There was no apparent effect of contiguous habitat patch size on salamander density nor genetic diversity, but we did observe significant genetic differentiation between 97% of pairwise population comparisons. The differentiation observed was not a result of overland distance or effective distance due to landscape resistance. There was evidence of historic bottlenecks at every site. These results suggest that density is driven by within-patch heterogeneity and that genetic diversity is affected by drivers other than patch size or contemporary population density. Our study demonstrates that red-backed salamanders can persist in wooded, urban parks, but that genetic diversity remains susceptible to demographic changes.