Metal and arsenic impacts to soils, vegetation communities and wildlife habitat in southwest Montana uplands contaminated by smelter emissions: I. Field evaluation

Concentrations of arsenic and metals in soils surrounding a smelter in southwest Montana were correlated with vegetative community structure and composition and wildlife habitat quality. Soils in the uplands surrounding the smelter were highly enriched with arsenic and metals. Concentrations of these analytes decreased with distance from the smelter and with soil depth, suggesting that the smelter is the source of the enrichment. In enriched areas, marked modifications to the native vegetation community structure and composition were observed. These included replacement of evergreen forest with bare unvegetated ground; species impoverishment and increased dominance by weed species in grasslands; and reductions in the vertical complexity of the habitat. Significant negative correlations existed between soil arsenic and metals concentrations and the extent of vegetative cover and the vertical diversity of plant communities. Loss of vegetative cover in the affected areas has been accompanied by reductions in their capacity to support indigenous wildlife populations.