Habitat-dependent responses of terrestrial salamanders to wildfire in the short-term

Abstract

Wildfire is an important natural disturbance event that promotes landscape heterogeneity and regulates many wildlife communities. The compounding effects of fire suppression and climate change have increased the frequency and severity of wildfire, but the responses of many organisms to wildfire is unknown. Landscape heterogeneity, specifically microhabitats, may mediate and buffer the effects of wildfire, and evaluating variable responses to wildfire given habitat is key to developing a more cohesive understanding of population responses. Terrestrial plethodontid salamanders are likely disproportionality affected by wildfire events because of their lungless anatomy and reliance on cool and moist habitats. Our knowledge of salamander responses to wildfire in the short-term is limited due to the inherent challenge of opportunistically studying post-wildfire events. We capitalized on a wildfire event in western North Carolina, USA to determine the short-term (6–18-month post-fire) habitat-mediated responses of salamanders to wildfire using body size measurement and repeated count surveys. We observed precipitous declines of the red-legged salamander, Plethodon shermani, in exposed upland forests, but no apparent negative effects in riparian forests 18-months post-fire relative to unburned sites. We also observed a loss of juvenile size classes in the upland burned forest with only the largest adult individuals remaining 18-months post-fire. There were no size class differences in the riparian forests. Our results suggest riparian forests may be buffered from the effects of wildfire because canopy cover, vegetation, and soil duff layer are retained following a wildfire event. Salamander populations inhabiting riparian forests may be at less risk of declining than those in exposed habitats. Our results underscore the need to assess wildfire effects in all habitat types to fully determine the effects of disturbance to populations.