Eastern Redback Salamander Abundance in North Central Massachusetts 2005

Throughout the twentieth century several dominant tree species suffered severe decline in the eastern United States due to non-native pests and pathogens, yet little is known of the effects these losses have on ecosystem processes or associated wildlife populations (Orwig 2002). Eastern hemlock (Tsuga canadensis), an important late-successional tree species, is currently threatened throughout its range by the hemlock woolly adelgid (Adelges tsugae; HWA), an invasive insect pest native to Japan (Orwig and Foster 1998). The unique structure and microenvironment of hemlock-dominated forests create critical landscape level heterogeneity, providing habitat for numerous bird and mammal species several of which are strongly associated with hemlock stands in the Northeast (Yamasaki et al. 2000). The effects of hemlock loss on associated wildlife is largely unknown, but is of particular concern for terrestrial salamanders as they are sensitive to microclimatic conditions that are likely to change as hemlocks decline. In this study, populations of eastern red-backed salamanders (Plethodon cinereus), significant contributors to the overall vertebrate biomass in northeastern forests (Burton and Likens 1975a), are compared in hemlock-dominated and mixed deciduous forest. The objectives of this study was to 1) to determine whether the relative abundance, body condition, and size class structure of P. cinereus populations differ in hemlock-dominated forests versus mixed deciduous forests in north-central Massachusetts. A difference in age-class structure in the two forest types may suggest a difference in survivorship, while differences in body condition are driven by differences in the energy expenditure required to obtain food resources and can lead to differences in reproductive success 2) to evaluate how structure and microenvironment differ and determine which variables best predict the variation in relative abundance and body condition of P. cinereus in the two forest types. Results from earlier work as well as evidence that cooler, moister habitat and higher abundance of prey is found in hemlock-dominated forest led me to hypothesize that P. cinereus relative abundance and body condition would be higher in plots in this forest type.