Since the Buck Mountain coal seam was accidentally set on fire in 1962, the mine fire beneath the small town of Centralia, Pennsylvania, USA has spread beneath more than 600 hectares. Among its effects are raised ground temperatures, elevated carbon dioxide concentrations in the soil, and altered vegetation patterns. To understand the relationship between plant diversity and the stresses of a mine fire, temperatures, carbon dioxide concentrations, and diversity indexes were correlated. Fire-impacted vegetation falls into three communities: one consisting almost exclusively of mosses (Leucobryum ssp.) and purslane (Portulaca oleracea), another of various grasses (Poaceae family), and a third of mixed grasses and forbs (such as asteraceae and plantaginaceae). Soil gas and ground temperatures were collected from 1 m² plots in each of these communities. Species coverage was estimated in each plot and used to calculate Simpson's Index of Dominance, Shannon-Weiner Diversity Index, and species richness. These parameters were also measured at control sites where the fire has not affected the surface. Collected soil gas was analyzed using a gas chromatograph, and multivariate regression was used to find relationships between temperature, CO₂, species richness, Simpson's Index, and the Shannon-Weiner Index. Mean ground temperatures were 23°C to 39.6°C in the summer and 21.4°C to 46.8°C in the fall, while carbon dioxide ranged between 0.87% and 1.23% in the summer and between 0.53% and 2.32% in the fall. Vegetation patterns were found to be mostly temperature dependant, though CO₂ concentration levels also impacted diversity. In addition to causing obvious air pollution, this uncontrolled fire is producing a significant loss of biodiversity in the affected zones as soil temperature and carbon dioxide concentrations rise.