Changes in soil properties and vegetation following disturbance of Alaskan arctic tundra.
Abstract
Soil characteristics and vegetation were studied in vehicle tracks and adjacent undisturbed tundra along local moisture gradients at four sites in northern Alaska. Vehicle tracks generally had 2 deg C higher soil temperatures, deeper thaw and higher concentrations of available soil phosphate than adjacent undisturbed tundra, but did not differ consistently from controls in soil bulk density, volumetric moisture content, pH or soil organic content. Vegetation in vehicle tracks had fewer species than controls, owing to decreased abundance of shrubs, particularly evergreens, and increased dominance by a few species of graminoids. Wet and mesic tracks exhibited a 2- to 15-fold increase in above-ground standing crop of nitrogen and phosphorus as a result of increased leaf nutrient concentrations and increased leaf biomass of graminoids, a consequence of increases in both shoot density and shoot weight. It is concluded that temperature effects upon root growth, nutrient absorption and organic matter mineralization are insufficient to account for the increased standing crop of biomass and nutrients in vehicle trails, and that other factors, perhaps related to soil water and nutrient movement, are largely responsible for the increased nutrient status and production of vehicle tracks.