Taiga Plains High Subarctic Ecoregion
Overview
The Taiga Plains High Subarctic (HS) Ecoregion occupies the northern third of the Taiga Plains. Undulating to hummocky till plains, slow-growing white and black spruce forests, and active permafrost features such as polygonal peat plateaus and earth hummocks are characteristic.
General Description
The Level III Taiga Plains HS Ecoregion includes fourteen Level IV ecoregions that occupy the northern third of the Taiga Plains. The Taiga Plains HS Ecoregion spans approximately 400 km in a south-north direction. North of the 68th parallel, closed and open forests of white and black spruce give way to sparsely treed white spruce woodlands. Features characteristic of Low Arctic climates, such as patterned ground, earth hummocks, and treeless tundra become more common along the indistinct boundary with the Level II Southern Arctic Ecoregion. Gently sloping, level and undulating till occurs over much of the area, with some areas of significant topography. Peatlands are extensive in a few of the Level IV ecoregions, but occupy a relatively small proportion of the total area within the Taiga Plains Ecoregion relative to more southerly Level III ecoregions. Recent fires have burned over much of the region, and regenerating shrub lands are a widespread cover type. White spruce is the dominant tree species; density and vigour are a function of latitude, with closed stands more common in the south and very open, low-canopied woodlands in the north.
Climate
Inuvik is the only station in the region from which climate data have been collected over long periods, and climatic statistics have been modelled over large areas using these limited data. The climate is colder than the Taiga Plains LS Ecoregion to the south, and is characterized as High Subarctic by the Ecoregions Working Group (1989). Polygonal peat plateaus are the dominant wetland form, earth hummocks and patterned ground become common near the region’s northern boundary, and tree growth becomes increasingly suppressed with increasing latitude. Climate models (Agriculture and Agri-Food Canada 1997) provide the following general statistics. The mean annual temperature ranges from –5 to –11ºC.The mean temperature in January, the coldest month, ranges from –27 to –29ºC, and from 8 to 16.5ºC in July, the warmest month. Mean annual precipitation is between 170 and 340 mm, with the wettest period in June through October and the driest period in December through April; about half falls as rain and half as snow. The mean annual daily solar input (refer to Section 1.4.1 for further explanation) ranges between 9.0 and 10.0 mJ/m2/day, with low values of 0 to 0.6 mj/m2/day in December and highs of 22 to 22.5 mJ/m2/day in June.
Topography, geology, soils, and hydrology
The Taiga Plains HS Ecoregion includes level to hummocky plains, rolling and ridged uplands with significant bedrock exposures in places, and Canada’s largest delta. Undulating to hummocky, fine-textured and often bouldery till deposits is the most common landform. Peatlands are more extensive south of the Mackenzie Delta. Permafrost is continuous, and soils are dominantly mineral and Organic Cryosols. There are numerous lakes; Great Bear Lake, Canada’s largest lake, lies entirely within this Ecoregion.
Vegetation
White spruce communities are the most common vegetation types; the species composition of white spruce communities is fairly consistent across the Ecoregion, but progressively more rigorous climates at higher latitudes result in reduced tree height and density, culminating in the transition to shrub-dominated tundra along a broad, poorly defined boundary with the Level II Southern Arctic Ecoregion. Extensive fires have resulted in large areas of regenerating dwarf birch. Treeless lichen-dwarf birch communities cover polygonal peat plateaus. Jack pine does not occur in this Ecoregion; trembling aspen does occur, but only as stunted individuals on south-facing slopes and well-drained alluvial terraces.
Ecoregions
The following are the smaller ecoregions within the Taiga Plains HS Ecoregion:
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Mackenzie Delta HS Ecoregion
Arctic Red Plain HS Ecoregion
Campbell Hills HS Ecoregion
Sitidgi Plain HS Ecoregion
Travaillant Upland HS Ecoregion
Anderson Plain HS Ecoregion
Colville Upland HS Ecoregion
Colville Plain HS Ecoregion
Colville Hills HS Ecoregion
Great Bear Upland HS Ecoregion
Great Bear Plain HS Ecoregion
Grandin Plain HS Ecoregion
Grandin Upland HS Ecoregion
Lac Grandin Upland HS Ecoregion
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Click here for more information on the Taiga Plains HS Ecoregion and all of the Level IV ecoregions within it.
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Total area: 170,034 km2 (35% of Taiga Plains)
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