The Role of Snow Cover in Limiting Surface Disturbance Caused by Winter Seismic Exploration

Abstract

The relationship between snow cover and the degree of surface disturbance caused by winter seismic vehicles was investigated on the Arctic Coastal Plain of the Arctic National Wildlife Refuge in northeastern Alaska. Ninety study plots were established on seismic lines and camp moves in tussock tundra and moist sedge-shrub tundra. Total snow depth and its components, slab layer and depth hoar, were measured during the winter. Plant cover changes, tussock disturbance, visibility and disturbance levels were determined at the study plots in the summer. Disturbance was found to be generally lower when snow depths were greater. In tussock tundra, plots with snow depths over 25 cm had significantly less disturbance than those with under 25 cm (p <0.05). The relationship between snow cover and disturbance was less clear in moist sedge-shrub tundra, where disturbance appeared to be less at snow depths above 25 cm, but these differences were not statistically significant (p <0.05). Slab depth, which does not include the loose layer of depth hoar, provided a better measure of protective snow cover in most sedge-shrub tundra, as slab depths over 20 cm resulted in significantly less disturbance (p <0.05). Moderate-level disturbance (25-50% decrease in plant cover) did not occur on trails where snow depths were at least 25 cm in tussock tundra and 35 cm in moist sedge-shrub tundra. Low-level disturbances (less than 25% decrease in plant cover) occurred on trails with snow depths as high as 45 cm in tussock tundra and 72 cm in moist sedge-shrub tundra.

Key words: surface disturbance, winter seismic exploration, seismic trails, tundra, snow depth, Alaska, Arctic National Wildlife Refuge, Arctic Coastal Plain