With projected decreases in biodiversity looming due to changing environmental conditions, it is important for conservation managers to have accurate predictions of species’ distributions. Species distribution modeling (SDM) and mechanistic modeling approaches that account for biophysical factors are important tools for predicting potential distributions and range limitations for many species. Recent advances in microclimate modeling have allowed for the incorporation of microclimate models into SDMs and other mechanistic approaches, a critical step for developing biologically relevant models for the variety of organisms reliant on microclimatic regimes. However, there remains a need to integrate microclimate-derived SDMs and mechanistic models at fine spatio-temporal scales to quantify and limit model uncertainty. In this study, we developed microclimate SDMs and mechanistic models of dispersal resistance for two plethodontid salamanders at a fine spatial resolution (3 m2) across Great Smoky Mountains National Park, USA during the 2010, 2030, and 2050 time periods. We determined the spatio-temporal agreement between microclimate SDMs and dispersal resistance to assess model uncertainty. We also modeled microclimate dispersal corridors and assessed spatio-temporal variability within these pathways. We found that agreement between microclimate SDMs and dispersal resistance models was generally poor. Importantly, model agreement varied across temporal periods and at differing spatial extents and resolutions. Furthermore, dispersal corridors varied temporally and demonstrated increased habitat fragmentation under future projections. The findings from this study highlight a potential contradiction in which we have a need to model species distributions with microclimate data at finer, more biologically meaningful resolutions but model agreement between correlative and mechanistic approaches may be weakened at these fine scales. Further quantifying model uncertainty and working on alternative methods for integrating SDMs and mechanistic models at fine-scale resolutions will be an important step towards accurately predicting species distributions under changing environmental conditions.

Climate change is expected to systematically alter the distribution and poEurycea pulation dynamics of species around the world. The effects are expected to be particularly strong at high latitudes and elevations, and for ectothermic species with small ranges and limited movement potential, such as salamanders in the southern Appalachian Mountains. In this study, we sought to establish baseline abundance estimates for plethodontid salamanders (family: Plethodontidae) over an elevational gradient in Great Smoky Mountains National Park. In addition to generating these baseline data for multiple species, we describe methods for surveying salamanders that allow for meaningful comparisons over time by separating observation and ecological processes generating the data. We found that Plethodon jordani had a mid-elevation peak (1500 m) in abundance and Desmognathus wrighti increased in abundance with elevation up to the highest areas of the park (2025 m), whereas Eurycea wilderae increased in abundance up to 1600 m and then plateaued with increasing uncertainty. In addition to elevation, litter depth, herbaceous ground cover, and proximity to stream were important predictors of abundance (dependent upon species), whereas daily temperature, precipitation, ground cover, and humidity influenced detection rates. Our data provide some of the first minimally biased information for future studies to assess changes in the abundance and distribution of salamanders in this region. Understanding abundance patterns along with detailed baseline distributions will be critical for comparisons with future surveys to understand the population and community-level effects of climate change on montane salamanders.