The spatial pattern of plants reflects biotic and abiotic factors, including interactions with surrounding environmental conditions and other plants. Appalachian heath systems are presently understudied regarding spatial point pattern research, despite representing a unique and biologically valuable ecosystem. In this study, we characterized the spatial pattern of three tree species distributions in the upland heath barrens on Cabin Mountain in Canaan Valley, West Virginia through fieldwork, statistical modeling, and the use of geographical information systems (GIS). The research objectives were to: 1) quantify the global and local spatial patterns of trees to infer biotic process, and 2) identify how tree spatial pattern varies with selected biophysical variables, including ground curvature and topographic wetness index, to understand potential relationships between ambient conditions and spatial pattern. The spatial statistics, Ripley's K-function and nearest neighbor analysis, presented a series of different interaction types reflected across size-growth classes and species where the null hypothesis was rejected for some pairs and supported in others. The selected biophysical variables had no significant relationship to spatial pattern at the site. These findings suggest a range of both intraspecific and interspecific interactions are taking place in the heath barrens of Cabin Mountain, where significant levels of facilitation are occurring among encroaching red maple and striped maple, while red spruce is in competition with both species of maple, and that relationships are formed outside the influence of topographic characteristics of the site. / Master of Science / The spatial pattern of plants reflects biotic and abiotic factors, including interactions with surrounding environmental conditions and other plants. Appalachian heath barrens are presently understudied in regard to spatial point pattern research, despite representing a unique and biologically valuable ecosystem. In this study, we characterized the spatial pattern of three tree species in the red spruce heath barrens on Cabin Mountain in Canaan Valley, West Virginia through fieldwork, statistical modeling, and the use of geographical information systems (GIS). The research objectives were to: 1) quantify demographics and the spatial pattern of trees to assess for ongoing plant interaction, and 2) understand whether tree spatial pattern is affected by selected biophysical variables, including ground curvature and topographic wetness index, to understand potential relationships between environmental conditions and spatial pattern. The results suggested a range of interactions were occurring across the plot, intraspecies, different species-pairs, and size-growth classes. Most notably, encroaching striped and red maple species, had a positive relationship, while red spruce and both maple species had largely competitive relationships. Both topographic wetness index and ground curvature had no significant relationship to spatial pattern at the site. These findings suggest a range of both intraspecific and interspecific interactions are taking place in the heath barrens of Cabin Mountain, indicating the possibility of conversion from red spruce heath barrens to deciduous forest, that this pattern is formed outside the influence of topographic characteristics of the site.