Life history mediates the effects of habitat variation on salamander abundance: a multiscale assessment

Context The conservation of aquatic and semi-aquatic species is dependent on our understanding of species responses to fine and broad-scale habitat heterogeneity. This is particularly true for species of semi-aquatic salamanders, which show dramatic differences in life history strategies. To better conserve salamander biodiversity, it is therefore important to identify how species within stream communities respond to environmental conditions at multiple spatial scales. Objectives Stream salamanders are a group of amphibians that require permanent stream flow for reproduction and larval development. While research focusing on plethodontid salamander abundance exists, few have identified how abiotic factors at different scales influence stream salamander density. We aim to determine how responses to habitat factors at different scales differ between species of stream salamanders that have variable life history strategies. Methods We conducted area-constrained repeated count surveys in stream reaches across three watersheds in western North Carolina. We surveyed each plot on three occasions and estimated salamander density based on fine and broad-scale habitat covariates. Results We found species’ responses to stream water-quality and broad-scale landscape variability were dependent on larval period and adult life history. Species with more aquatic life histories had stronger responses to both water-quality and broad-scale variables, while more terrestrial species responded more strongly to broad-scale variables. Conclusions Responses to fine and broad-scale habitat variation by stream-salamanders is associated with species larval period and adult life history. Proper assessment of communities of semi-aquatic salamanders, therefore, requires an understanding of both upland and stream conditions, especially when diverse life histories are present.