Nitrogen Availability and Vegetational Community Structure on a Cliff System in the Southern Appalachians

While research in almost every ecosystem confirms the importance of nutrient cycling to community dynamics, it has been an under-investigated aspect of cliff ecology. This study explores the influence that nitrogen availability and other abiotic variables have on the diversity of vegetation communities on a cliff ecosystem in the southern Appalachian Mountains near Todd, NC, USA. Analysis of abiotic variables (slope, aspect, surface heterogeneity, soil cover, NO3-N, and NH4-N) partially confirmed observations from previous studies demonstrating that surface heterogeneity has a positive relationship and slope has a negative relationship with regard to total species diversity. Nitrogen availability along the cliff face increased with surface heterogeneity and soil depth. In addition, total vegetational species diversity declined with increasing nitrogen availability. This study is consistent with previous studies of cliff community response to basic abiotic variables and with studies that investigate the response of biota in non-cliff habitats to varying levels of nitrogen. Furthermore, the data presented in this study provide the first community level investigation of nitrogen cycling on a cliff and show that nitrogen availability is correlated both with existing abiotic variables and with the total vegetational species diversity of the studied cliff.