Vehicle Perturbation Effects upon a Tundra Soil‐Plant System: II. Effects on the Chemical Regime

Chemical regime alterations of a soil‐plant system resulting from tracked‐vehicle perturbation were determined in Tundra soils near Barrow, Alaska. The study was a contribution to the USIBP Tundra Biome Program. Six years following the perturbation, soils within track scars had lower redox potentials (negative) and lower amounts of exchangeable acidity than undisturbed soils. Furthermore, exchangeable bases (Ca, Mg, K and Na) were higher in the track influenced soils. Consequently, soil pH and base saturation were also higher. Soluble nutrient (Ca, Mg, K, Na, and NH 4 ‐N) levels in soil solutions were considerably higher in track‐influenced soils than in undisturbed soils. Correspondingly, soil solution pH was also higher. Plants growing in the altered environment of the track scars were enriched in nutrients and were larger in size. Increased productivity and quality of track‐influenced vegetation was apparently stimulated by an increase in available nutrients in less acid, warmer, nutrient enriched soils. The track perturbation also resulted in changes in floristic composition of the vegetation at different locations within track‐affected soils. The intensity of soil alteration and resulting changes in the soil‐plant chemical regime were related to the degree of scarring of the landscape which, in turn, was related to differences in the natural drainage of soils along the tracks; scarring being greater, the poorer the natural drainage. Results show that a slight amount of disturbance to the tundra surface may be beneficial in terms of increased productivity and nutrient content of vegetation.