Roadside Vegetation Health Condition and Magnesium Chloride (MgCl 2 ) Dust Suppressant Use in Two Colorado, U.S. Counties

Many abiotic and biotic factors affect the health of roadside vegetation, including the application of magnesium chloride (MgCl2) dust suppression products. Three hundred seventy kilometers (230 mi) of forested, shrubland, meadow, rangeland, riparian, and wetland roadside habitats were surveyed along major nonpaved roads in two Colorado counties. Dominant species composition and visible damages of woody roadside vegetation were quantified. The majority (72.3% to 79.3%) of roadside vegetation surveyed was considered healthy (less than 5% damage to crown or stem), depending on slope position from the road. Severely damaged (greater than 50% damage) vegetation ranged from 6.4% to 11.4% of roadside cover, with the most severely damaged vegetation occurring downslope from the road. Percent of plants with severe or moderate damage increased with increasing MgCl2 application rates for roadside aspen, Engelmann spruce, and lodgepole and ponderosa pines. Further research is needed to determine the distribution of MgCl2 ions, nutrients, and interactions between MgCl2 and incidence of potential biotic damage agents in roadside soils and plants.