Individual, population and landscape-scale effects of timber harvest on the red-legged salamander (Plethodon shermani)

Abstract

Habitat loss and alteration are widely recognized as major threats to global biodiversity and the vulnerability of animal species to these disturbance processes can depend on the behavioral responses of individuals to modified landscapes. In response to a changing environment, individuals may either attempt to adapt to changing conditions or disperse to new habitat. At the local scale, the emigration of individuals or changes in activity patterns could lead to reduced counts of animals in ecological studies. At broader spatial scales, organismal movement may enable population rescue or reestablishment after disturbance and maintain demographic connectivity among populations. These complex mechanisms underlying the perceived abundance and distribution of species often requires a careful deconstructing of demographic trends and sampling variation in ecological data. Lungless salamanders (Family Plethodontidae) are extremely abundant in many forest and headwater stream ecosystems of eastern North America. These salamanders breathe across their moist skin surface, making them sensitive to fluctuations in temperature and moisture conditions. Thus, changes in habitat characteristics are known to have a considerable effect on populations of these salamanders. However, studies identifying the behavioral or demographic causes of declines as well as patterns of long-term recovery are critically needed. My dissertation research combined behavioral, population and landscape-scale studies to identify the effects of timber harvest on a lungless woodland salamander (Plethodon shermani). The primary objectives of my research were to 1) to describe the short-and long-term effects of timber harvest on salamander abundance and 2) to determine the behavioral or demographic processes dictating the abundance and distribution of salamanders at both local and landscape scales. To characterize baseline population dynamics of the salamander, P. shermani, I conducted a 5-year capture-mark-recapture study which revealed substantial annual