Road Dust and Its Environmental Impact on Alaskan Taiga and Tundra

The physical and chemical characteristics and ecological consequences of road dust in arctic regions are reviewed with emphasis on recent information gathered along the Dalton Highway and the Prudhoe Bay Spine Road in northern Alaska. The primary observed ecological effects of dust are (1) early snowmelt in roadside areas due to lower albedos, resulting in a snow-free band of vegetation within 30 to 100 m of the road in early spring, which is used by waterfowl and numerous other species of wildlife; (2) a decrease in Sphagnum and other acidophilous mosses near the road; (3) an increase in many minerotrophic mosses; (4) a decrease in soil lichens, particularly species of Cladina, Peltigera, and Stereocaulon; (5) elimination of corticolous lichens near the road in areas of particularly high dust fall; (6) a general opening of the ground cover near the road and a consequent colonization of these barren surfaces by many taxa that are common on mineral-rich soils; (6) few effects on vascular plant abundance xcept in areas of very high dust, where ericaceous taxa and conifers are affected; (7) increased depth of thaw within 10 m of the road, possibly due to decreased plant cover and earlier initiation of thaw; and (8) contribution to thermokarst in roadside areas. Enhanced dust control measures should be considered, particularly where the road passes through scenic lichen woodlands, acidophilous tundra, annd in calm valleys where dust commonly is a traffic safety hazard.