METAL AND ARSENIC IMPACTS TO SOILS, VEGETATION COMMUNITIES AND WILDLIFE HABITAT IN SOUTHWEST MONTANA UPLANDS CONTAMINATED BY SMELTER EMISSIONS .1. 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 su rrounding the smelter were highly enriched with arsenic and metals. Co ncentrations of these analytes decreased with distance from the smelte r and with soil depth, suggesting that the smelter is the source of th e enrichment. In enriched areas, marked modifications to the native ve getation community structure and composition were observed. These incl uded replacement of evergreen forest with bare unvegetated ground; spe cies impoverishment and increased dominance by weed species in grassla nds; and reductions in the vertical complexity of the habitat. Signifi cant negative correlations existed between soil arsenic and metals con centrations and the extent of vegetative cover and the vertical divers ity of plant communities. Loss of vegetative cover in the affected are as has been accompanied by reductions in their capacity to support ind igenous wildlife populations.