Demography and space‐use of Eastern Red‐backed Salamanders (Plethodon cinereus) between mature and successional forests

Abstract

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.

Should landscape variation in population status be assessed with individual‐ or population‐level indicators?

“…Amphibians are regularly invoked as good indicators of environmental quality despite studies documenting wide variation in tolerance to environmental change (Vitt et al 1990, Kerby et al 2010, Cecala et al 2018). Beyond these traits, small amphibians have established morphometric relationships with body fat content (MacCracken and Stebbings 2012) and body size has been documented to vary across environmental gradients (Welsh et al 2008, Gade et al 2023). Furthermore, occupancy and abundance of stream‐breeding amphibians are sensitive to changes in fine‐ and broad‐scale environmental gradients linked to habitat suitability for larval and adult life stages (Surasinghe and Baldwin 2014, Grant et al 2016, Gould et al 2017, Cecala et al 2018, Gould and Peterman 2021).…”