VEHICLE TRACKS ON HIGH ARCTIC TUNDRA - THEIR EFFECTS ON THE SOIL, VEGETATION, AND SOIL ARTHROPODS

1. Examination of the effects of vehicle and pedestrian tracks of known age (13 or more years) and intensity of use (single to multiple passages) on vegetation, soil chemistry, soil arthropods, soil thaw characteristics, and small-scale hydrological changes showed clear and inter-related patterns. 2. In general, all tracks, regardless of age, showed small increases in the depth of thaw beneath them (c. 2.8 cm). 3. Tracks were generally depleted of carbon and to a lesser, but significant extent, of potassium and phosphorus. Slight increases in NO3, NH4, and calcium were noted. Magnesium and total nitrogen seemed unaffected. 4. On all tracks which had suffered multiple passages vegetation cover was significantly reduced. In a few sites where single passages were recorded, cover increased through proliferation of the sedge, Kobresia myosuroides. 5. Abundance of soil arthropods was significantly reduced on tracks, but the diversity was not. 6. In most sites, soil moisture and over-ground water flow did not seem affected. Only in sedge meadows where compression from a single passage resulted in channelling of water, and where multiple passages removed vegetation and initiated gulley erosion, were effects serious.