Natural plant recolonization of surficial disturbances, Tuktoyaktuk Peninsula Region, Northwest Territories

Abstract

Seismic lines or winter roads were sampled where they passed through three different plant communities in the Mackenzie Delta and through four of the major tundra communities in the Tuktoyaktuk Peninsula. Winter seismic lines have been less detrimental than summer lines for all communities examined. Although winter roads through upland areas remove most of the vegetation cover, the peat layer usually remains intact and soil energy budgets are relatively little affected. Wetland sedge meadows are highly susceptible to summer disturbance but least affected by winter operations. Winter-disturbed forested and tall shrub communities recover faster initially than similarly disturbed upland tundra communities.Eriophorum vaginatum and Carex bigelowii appeared to be stimulated by disturbances which did not eliminate them, with Eriophorum often flowering more abundantly in disturbed areas. This probably results from warmer soils and greater nutrient uptake.Summer seismic lines (1965), originally bladed to permafrost, resulted in exposure of mineral soil and thus led to secondary succession in tundra communities. Arctagrostis latifolia, Calamagrostis canadensis, Poa arctica, and Luzula confusa are the most typical and abundant pioneers of upland mesic sites. Wet sites are colonized predominantly by Arctophila fulva and Carex aquatilis. Once established, these species expanded rhizomatously. Six years after exposure of mineral soil, plant cover was usually 30 to 50%.Thaw was generally increased 80 to 100% where mineral soil was exposed, 30 to 50% if the peat remained intact, and 10% if plant cover was little altered. Subsurface ice has occasionally been exposed, resulting in thermokarst subsidence. Water erosion has not been a factor, probably because of the low precipitation in the region.