Impact of copper smelter emissions on subalpine vegetation in the Anaconda-Pintler Range

For nearly a century, the Anaconda Copper Smelter at Anaconda, Montana was the largest industrial point source of sulfur dioxide (SO2) and heavy metal particulates in Montana. While in operation in 1978, the year this study was initiated, the smelter emissions averaged 700 tons of SO2 and 30 tons of particulates daily. This research examines the ecological impacts and the spatial distribution of the phytotoxic emissions on subalpine plant communities in the Anaconda-Pintler Range southwest of Anaconda. Using stratified random sampling, ridgetop stands in three comparable habitat types were measured along a distance and elevational gradient from the smelter. The measured parameters included plant cover and species diversity; stand age, height, diameter, and stocking; and conifer foliage retention, injury, and chemical content. The sampling results indicate that the smelter pollution has significantly injured plant life in the study area. The stands with the highest levels of sulfur and copper in conifer foliage have the sparsest plant cover, the lowest stocking levels, and exhibit an accelerated rate of needle injury and abscission. Smelter contamination is generally reduced in the higher elevation communities compared to approximately equidistant lower slope stands. Among the lower elevation sites, the relative distribution of the pollutant impact is influenced by the configuration of the mountain topography and does not follow a straight line distance gradient from the smelter