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Ecological Framework of Canada
Ecoregions of Canada


This ecoregion stretches north from Lake Athabasca to beyond the east arm of Great Slave Lake. It is marked by cool summers and very cold winters, and has a subhumid, high boreal ecoclimate. The mean annual temperature is approximately -5°C. The mean summer temperature is 11°C and the mean winter temperature is -21.5°C. The mean annual precipitation ranges 200-375 mm. Yellowknife, on the north shore of Great Slave Lake, has the lowest mean annual temperature of all Canadian cities (-5°C) and the lowest average nighttime winter temperature (-30°C). Vegetation in the ecoregion is characterized by medium to tall, closed stands of trembling aspen and balsam poplar with white spruce, balsam fir, and black spruce occurring in late successional stages. Poorly drained fens and bogs are covered with low, open stands of tamarack and black spruce and have localized permafrost. North of the East Arm Hills, and in the southern one-third of the ecoregion, ridged to hummocky crystalline bedrock forms broad, steeply sloping terrain. The East Arm Hills, formed of down-faulted and folded, differentially eroded sediments and gabbro sills, dip southerly, forming broad cuestas as much as 275 m above Great Slave Lake, the surface of which is about 150 m asl in elevation. The intervening valleys are flooded by arms of Great Slave and other lakes. Upland elevations are dominated by bedrock exposures with discontinuous veneers of sandy till, whereas the lowlands are covered by level to gently undulating organic deposits. The ecoregion contains numerous small lakes, often linked by fast-flowing streams that eventually drain into Great Slave Lake. Strongly glaciated rock outcrops are common, and Dystric Brunisols are the dominant soils. Significant inclusions are Turbic Cryosols on permanently frozen sites and Organic Cryosols in poorly drained, peat-filled depressions. Permafrost is extensive and discontinuous with low ice content and sparse ice wedges throughout most of the ecoregion, with the exception of the west side between Lake Athabasca and Great Slave Lake towards the Slave River. Wildlife includes moose, black bear, woodland caribou, wolf, beaver, muskrat, snowshoe hare, and spruce grouse. Land uses include limited local sawlog forestry, outdoor recreation, wildlife trapping and hunting, and fishing. Major communities include Yellowknife, Uranium City, Reliance, Rae, Edzo, and Fort Chipewyan. The population of the ecoregion is approximately 18 100.

This ecoregion is part of the Taiga Shield ecozone.