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Ecological Framework of Canada
Ecoregions of Canada

SIBBESTON LAKE PLAIN

This ecoregion lies in the southwest corner of the Northwest Territories. It is bisected by the southern extension of the Franklin Mountains west of the Mackenzie River, and forms a series of linear, relatively low ranges and ridges (about 1650 m) consisting largely of resistant carbonates. The southern extension of the Mackenzie Plain, a broad, rolling, drift- and tree-covered plain lies to the west of the Franklin Mountains, and part of the Great Slave Plain lies to the east. The Great Slave Plain has generally little relief, and the surface below 300 m is characterized by low scarps of resistant carbonates and small shallow lakes. The narrow western extension of the ecoregion is composed of part of the Liard Plateau between the South Nahanni and Liard rivers. It is characterized by tree and alpine tundra covered hills (less than 1500 m), which are underlain mainly by Cretaceous shale and sandstone. The mean annual temperature is approximately -5°C. The mean winter temperature is -1°C and the mean summer temperature is 10°C. The mean annual precipitation ranges from 200 mm in the east to 350 mm in the west. This ecoregion is classified as having a low subarctic ecoclimate. It is dominated by open stands of black and white spruce, paper birch, and some aspen. There is an altitudinal transition from forest to alpine tundra, which occurs between 1050-1150 m. Wetlands cover approximately 50% of the ecoregion. Wet sites are usually covered with bog-fen vegetation such as dwarf black spruce, Labrador tea, ericaceous shrubs, and mosses. The ecoregion's surface materials consist of steeply sloping glacial drift, colluvium, and organic deposits in the form of peat plateaus, palsas, and fens. Dystric and Eutric Brunisols and Turbic Cryosols are the dominant soils. Permafrost is extensive and discontinuous with moderate to low ice content, and is characterized by sparse ice wedges. Characteristic wildlife includes caribou, moose, grizzly and black bear, wolf, coyote, beaver, snowshoe hare, muskrat, red fox, spruce grouse, raven, and osprey. Land uses include hunting, trapping, recreation, and tourism.

This ecoregion is part of the Taiga Plains ecozone.