Boreal Shield Ecozone (CEC)
The Boreal Shield Ecozone, as defined by the Commission for Environmental Cooperation (CEC), is the largest ecozone in Canada. Covering 1.8 million square kilometres it covers almost 20% of Canada's landmass, stretching from northern Saskatchewan to Newfoundland.
The retreat of the Laurentide Ice Sheet left a landscape of broadly rolling uplands and lowlands with precambrian granitic bedrock outcrops. Few clear drainage channels were left in the rocky sediments deposited by the glacier resulting in a deranged drainage pattern. The numerous wetlands and lakes formed give this ecozone a unique character. Water features in this ecozone contain 22% of Canada's freshwater surface area.
Soil types vary widely across the region in response to the wide range of climate and soil components present. Cryosols are found in the most northerly areas wherever there is permafrost. Accumulation of organic matter, particularly peat, results in organic soils in much of the area. Brunisols occur in the north and west of the region where coarse to medium sediments are found. In these soils, soil formation is ongoing and will eventually result in either podzols or luvisols. In the south and east, podzols are found under forests growing primarily on sand in cold conditions. Gleysols are found where poor drainage has resulted in depleted oxygen. Luvisols are present where forests overlay clay deposits. These two soil types occur across the region wherever these conditions occur.
The regional climate has long, cold winters and short summers, conditions which are moderated in coastal regions. Summers in the east are warmer than those in the west of the region. The mean annual temperature ranges from -4 °C in northern Saskatchewan to 5.5 °C in Newfoundland. Precipitation increases from west to east.
The region is widely forested with white and black spruce, balsam fir and jack pine. Deciduous trees are more common in the south, with white birch, trembling aspen and balsam poplar. There are also yellow birch and sugar maple to the east. In areas of muskeg there are stands of black spruce or tamarack. There are frequent forest fires.
Being largely wild and remote, this ecozone is rich in wildlife, including woodland caribou, moose, wolf, black bear, raccoon, marten, fisher, striped skunk, lynx, bobcat and eastern chipmunk. Common birds include Boreal owl, great horned owl, blue jay, white- sparrow and evening grosbeak. Lakes contain brook char, lake trout, northern pike, perch, and walleye.
Woodland Caribou on Holt Lake, Manitoba
Off the northern and eastern coasts, aquatic mammals include grey seal, harp seal, hooded seal, ringed seal, sperm whale, orca, Atlantic pilot whale, fin whale, blue whale, northern right whale, bowhead whale, and humpback whale.
Fire suppression, insect control, clear-cutting and single-species tree farming are widespread in accessible areas. These practices may, over the long term, reduce the diversity of both plant and animal species and increase the forest's vulnerability to disease.
Many Shield lakes and soils are extremely sensitive to changes in pH. Acid rain from local sources and from the long-range transport of airborne pollutants has already taken an ominous toll. It may be weakening the general vigour and growth rate of trees, as well as of aquatic species, in sensitive areas.
Each province continues to work on defining subregions within the larger national ecozone system.
- Tazin River Upland - Taiga Shield
- Churchill River Upland Ecoregion
- Hayes River Upland Ecoregion
- Lac Seul Upland Ecoregion
- Lake of the Woods Ecoregion
- Churchill River Upland Ecoregion
- Athabasca Plain Ecoregion
A number of protected areas have been established to protect representative and/or significant portions of this ecozone.
Under 3% of the ecozone's total land space forbids industrial activities of any kind; this land space is therefore designated as protected. Another 5% of the ecozone's land space is also considered protected, though not as strictly; activities such as mining or forestry may be tolerable in such areas. The Boreal Shield is the largest ecozone in Canada, however, compared to other ecozones, it exhibits among the smallest shares of land that have been deemed protected. Because the region is abundant in forest land, it is subject to extensive forestry practices.
In order to strengthen public dialogue and engagement on matters concerned with protected areas within the ecozone, land allocation programs have been adopted in Ontario and Saskatchewan. The programs consist of local and regional-level advisory groups that serve to help select and manage conservation areas in these provinces.
- "Boreal Shield". Canadian Atlas Online. Canadian Geographic. Retrieved 7 June 2014.
- Smith, R.E.; Veldhuis, H (1998). Terrestrial Ecozones, Ecoregions, and Ecodistricts of Manitoba An Ecological Stratification of Manitoba's Natural Landscapes (PDF). Winnipeg, Manitoba: Agriculture and Agri-Food Canada. p. 65.
- Dyke, A.S.; Prest, V.K. (1987). "Late Wisconsinan and Holocene History of the Laurentide Ice Sheet". Géographie Physique et Quaternaire. 41 (2): 237–263. doi:10.7202/032681ar.
- Pidwirny, M., (2006). "The Drainage Basin Concept". Fundamentals of Physical Geography, 2nd Edition.
- "Boreal Shield Ecozone: Landforms and Climate". Ecological Framework of Canada. Environment Canada. Retrieved 7 June 2014.
- "Forest & Tundra Soils - Soils of Canada". soilsofcanada.ca. University of Saskatchewan. Retrieved 22 September 2019.
- Torsten, Bernhardt. "Boreal Shield". Canadian Biodiversity. Torsten Bernhardt. Archived from the original on 24 November 2014. Retrieved 7 June 2014.
- "Ecozones Introduction". Canadian Council on Ecological Areas (CCEA). Retrieved 12 August 2017.
This level of generalization is well suited for national scale reporting. In the last 20 years, all Provinces and Territories have refined and automated their respective regional ecological framework. It is important, then, to provide a current national perspective which accurately reflects current regional efforts. ... Detailed ecological information remains with jurisdictions.
- "Natural Regions and Subregions of Alberta - Alberta Parks" (PDF). Alberta Parks. Retrieved 12 August 2017.
- Smith, R.E.; Veldhuis, H.; Mills, G.F.; Eilers, R.G.; Fraser, W.R.; Lelyk, G.W. (1998). "Terrestrial Ecozones, Ecoregions, and Ecodistricts of Manitoba An Ecological Stratification of Manitoba's Natural Landscapes" (Technical Bulletin 98–9E). Winnipeg, Manitoba: Land Resource Unit, Brandon Research Centre, Research Branch, Agriculture and Agri-Food Canada: 170. Retrieved 6 October 2017. Cite journal requires
- "Saskatchewan's Ecoregions". Saskatchewan Conservation Data Center. Retrieved 12 August 2017.
- Urquizo, Natty; Bastedo, Jamie; Brydges, Tom; Shear, Harvey. "Ecological Assessment of the Boreal Shield Ecozone" (PDF). publications.gc.ca. Government of Canada: Public Services and Procurement Canada. Retrieved 2019-04-11.