The Distribution of a Stream-breeding Salamander, Desmognathus ocoee, in Terrestrial Habitat Suggests the Ecological Importance of Low-order Streams

Small headwater streams are a common feature of many forested landscapes, and their integrity is considered critical to the maintenance of water quality and biodiversity within broader drainage networks. Although riparian buffer zones are often established to limit disturbance to stream ecosystems from human land use, various buffer zone management strategies may provide effective protection to certain aquatic or semi-aquatic species while only encompassing a portion of core habitat for other species. Thus, an improved understanding of species distributions within riparian forests can be useful for predicting the overall effectiveness of various forest management practices. In this study, we conducted area-constrained surveys for salamanders at 16 plots within terrestrial habitat. We then employed an information-theoretic (AIC) approach to model selection to quantify the distribution of aquatic-breeding Ocoee Salamanders, Desmognathus ocoee, within terrestrial habitat as a function of stream length, width, and/or proximity within the surrounding landscape. Based on a mechanistic model for salamander counts, we estimated that 95% of Ocoee Salamanders are distributed within 79 m of their stream of origin and that relative abundance should decline exponentially with distance into terrestrial habitat. However, a simple model describing salamander counts as an exponential decay with distance from the nearest stream received the strongest support overall, suggesting that this may represent a good predictive model for the distribution of D. ocoee in terrestrial habitat. Due to the prevalence of headwater streams and seeps which do not appear on topographic maps, protecting 95% of core terrestrial habitat around all stream features would require protecting 59.3% of our study landscape. Models describing the spatial distributions of semi-aquatic organisms within terrestrial habitat can be useful for providing spatially explicit density estimates for species conservation or management efforts.