Land-use change has been described as one of the most pervasive and threatening disturbance causing environmental change. These changes have cascading effects that negatively influence the distribution and dynamics of animal populations through direct and indirect pathways. Despite protection of much of the southern Appalachian Mountains, ex-urban development has the potential to influence patterns of diversity and abundance of stream organisms as the streams integrate changes occurring throughout the catchment. Although salamanders have been demonstrated to decline due to changes in land-use, the specific factors influencing these changes have not been identified. Thus, to determine how distributions of stream fauna were affected by ex-urban expansion of southern cities, we surveyed 37 sites in the headwaters of the Little Tennessee River and developed linear models to describe patterns of salamander occupancy due to variation in local, landscape, and sociological parameters.
Results/Conclusions
Linear models revealed that local, landscape, and sociological variables all influenced salamander occupancy. Catchment forest cover, local stream-temperature fluctuations, and time since first disturbance were the best predictors of salamander occupancy. Desmognathus quadramaculatus was most sensitive to changes in these variables with occupancy positively influenced by forest cover and time since first disturbance but negatively related to local stream-temperature fluctuations. As forest cover adjacent to the stream and in the catchment decreased, salamander communities became more simplistic, and Eurycea wilderae became the dominant species. Alternatively, forested sites had high abundances of the larger, more sensitive species, D. quadramaculatus. Humans modify stream catchments in a variety of ways that can negatively influence stream processes. Our analysis identifies important stream attributes influencing occupancy of salamander communities.
