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This ecoregion covers much of northern Saskatchewan, north-central Manitoba (north and east of Lake Winnipeg) and a portion of northwestern Ontario. This ecoregion is classified as having a subhumid high- to mid- boreal ecoclimate. It is marked by cool summers (except the Lac Seul Upland area which has warm summers) and very cold winters. The mean annual temperature ranges from -4°C to 0.5°C; the mean summer temperature ranges from 11.5°C to 14°C; and the mean winter temperature ranges from -20.5°C to -14.5°C. In each case, the Lac Seul Upland area represents the warmest temperature in the ecoregion , and the Athabasca Plain, Churchill River Upland and Hayes River Upland regions represent the cooler temperatures. Mean annual precipitation ranges from 350-700 mm, with the wettest areas being in the southeastern portions of the Lac Seul Upland and Hayes River Upland (ESWG 1995). Permafrost occurs sporadically throughout this ecoregion, except in the area of the Lac Seul Upland, which has a warmer climate. Wetlands are extensive in the regions of the Lac Seul Upland and the Athabasca Plain, and numerous small to large lakes are a prominent feature of the entire ecoregion. Archean rocks form steeply sloping uplands and lowlands in the Churchill River Upland and Hayes River Upland, while the Archean bedrock of the Lac Seul Upland area forms more broadly sloping uplands and lowlands. The ecoregion is covered with undulating to ridged glaciolacustrine or fluvioglacial deposits with occasional hummocky bedrock ridges and knolls (ESWG 1995).
A portion of this ecoregion (the Athabasca Plain and the Churchill River Upland) forms part of the continuous coniferous boreal forest that extends from northwestern Ontario to Great Slave Lake in the Northwest Territories. Forests of this ecoregion are dominated by stands of black spruce (Picea mariana) and jack pine (Pinus banksiana), with a shrub layer of ericaceous shrubs (Ericaceae) and a ground cover of moss and lichens. Depending on drainage, surficial material, and local climate, trembling aspen (Populus tremuloides), white birch (Betula spp.), white spruce (Picea glauca), balsam poplar (Populus balsamifera), and balsam fir (Abies balsamea) also occupy significant areas of this ecoregion. Poorly drained areas covered by fens and bogs are dominated by black spruce. Bedrock exposures have few trees and are covered with lichens. Fire is an important disturbance regime in this ecoregion, particularly on conifer-dominated dry sites, such as the Athabasca Plain (ESWG 1995). Characteristic wildlife include moose (Alces alces), black bear (Ursus americanus), woodland caribou (Rangifer tarandus ssp. caribou) (for whom there is important winter range in Athabasca Plain), barren-ground caribou (Rangifer tarandus ssp. arcticus), lynx (Lynx canadensis), wolf (Canis lupus), beaver (Castor canadensis), otter (Lontra canadensis), marten (Martes americana), ermine (Mustela erminea), fisher (Martes pennanti), muskrat (Ondatra zibethica), snowshoe hare (Lepus americanus), red-backed vole (Clethrionomys gapperi), red squirrel (Tamiasciurus hudsonicus), least chipmunk (Tamius minimus), ducks, geese, pelican (Pelecanus erythrorhynchos), sandhill crane (Grus canadensis), spruce grouse (Dendragapus canadensis), sharp-tailed grouse (Tympahuchus phasianellus), willow ptarmigan (Lagopus lagopus), common nighthawk (Chordeiles minor), red-tailed hawk (Buteo jamaiccensis), raven (Corvus corax), common loon (Gavia immer), bald eagle (Haliaeetus leucocephalus), gray jay (Perisoreus canadensis), hawk owl (Surnia ulula), great-horned owl (Bubo viriginanus), herring gull (Larus argentatus), double-crested cormorant (Phalacrocorax auritus) and several other passerine species (ESWG 1995). Freshwater lakes make up a significant component of the landscape. The Athabasca plain and basin contain some of the most significant, active sand dune systems in the boreal regions of North America. Habitat Loss and Degradation Up to 80 percent of this ecoregion remains as intact habitat, although that number drops to an estimated 65 percent in Manitoba. The principal causes of habitat loss are forestry (rapidly expanding), mining (uranium, nickel, gold, copper) and flooding from hydro-electric development. Remaining Blocks of Intact Habitat Most of the ecoregion remains relatively intact. Degree of Fragmentation Fragmentation of habitat is increasing. Principle causes are transportation routes, logging activity and roads, and flooding from hydro-electric projects. Degree of Protection
Types and Severity of Threats Major or potential increases in the annual allowable cut in large scale forestry licenses, new hydro-electric dams and major transmission corridors, and extensive mineral exploration are increasing the level of threat to this ecoregion as a whole.
Establish protected areas in the following locations:
 Relationship to other classification schemes The Midwestern Canadian Shield Forests span from northern Alberta east to western Ontario. The Athabasca Plain, Churchill River Upland, Hayes River Upland and Lac Seul Upland (TEC 87-90) are the regions within this ecoregion (Ecological Stratification Working Group 1995). Rowe’s (1972) Boreal forest sections include: Central Plateau, Upper and Lower English River, Upper Churchill, Nelson River, Northern Coniferous, Athabasca South and Northwestern Transition (8, 11, 14, 20, 21, 22a and b and 27). Prepared by: J. Shay, A. G. Appleby, G. Whelan Enns, T. Gray, K. Kavanagh, M. Sims, G. Mann. This text was originally published in the book Terrestrial ecoregions of North America: a conservation assessment from Island Press. This assessment offers an in-depth analysis of the biodiversity and conservation status of North America's ecoregions. All text by World Wildlife Fund © 2001 For more general information on this ecoregion, go to the WildWorld version of this description.
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