Taiga Plains High Boreal Ecoregion
Overview
The Taiga Plains High Boreal (HB) Ecoregion occurs at higher elevations in the southern Taiga Plains; it is surrounded by or lies immediately north of the lower-elevation Mackenzie and Slave Lowlands MB Ecoregion, and has a cooler climate.
General Description
The Level III Taiga Plains HB Ecoregion extends across the southern third of the Taiga Plains at elevations of 300 to 700 mASL; the six Level IV ecoregions within it are surrounded by or lie immediately north of the lower-elevation Mackenzie and Slave Lowlands MB Ecoregion. Relatively poor forest growth and a higher proportion of organic terrain and peat plateaus are indicative of colder conditions at higher elevations. Imperfectly- to poorly-drained and gently sloping, level and undulating till occurs over much of the area; it is frequently mantled by peatlands. Low-growing open black spruce forests, treed bogs, horizontal fens and peat plateaus are dominant. Hill slopes, till with local relief, or coarse-textured parent materials provide generally better drained and warmer local environments, and allow the development of upland deciduous, mixed-wood and coniferous forests.
Climate
The Taiga Plains HB Ecoregion has sparse long-term climate data. Cooler conditions, relative to the adjacent lower-elevation Taiga Plains MB Ecoregion are indicated by the increased extent of permafrost features (peat plateaus) and less vigourous forest growth on uplands. These conditions are characteristic of High Boreal climates as defined by the Ecoregions Working Group (1989). Summer precipitation is expected to be higher than on the surrounding plains because of convective storms that form over higher terrain (Klock et al. 2000). Climate models (Agriculture and Agri-Food Canada 1997) provide the following general statistics. The mean annual temperature ranges from –2.0 to –4.5ºC. The mean temperature in January, the coldest month, ranges from –24 to –28ºC, and from 15.5 to 17.0ºC in July, the warmest month. Mean annual precipitation is between 300 and 390 mm, with the wettest period in June through August and the driest period in December through April; about 55 percent falls as rain and 45 percent as snow. The mean annual daily solar input (refer to Section 1.4.1 for further explanation) ranges between 10.5 and 11.0 mJ/m2/day, with low values of 1.0 to 1.5 mj/m2/day in December and highs of 21.5 to 22.0 mJ/m2/day in June.
Topography, geology, soils, and hydrology
Hill systems at elevations of 300 to 700 mASL surrounded by the gently sloping to undulating plains of the Taiga Plains MB Ecoregion characterize four of the six Level IV ecoregions within the Taiga Plains HB Ecoregion; the other two Level IV ecoregions occur at more northerly latitudes. The most common landform is imperfectly- to poorly-drained glacial till on which Organic and Gleysolic soils or Organic Cryosols have developed. Brunisols and Luvisols occur along slopes and on hummocky or ridged till, or well-drained fluvial and glacio-fluvial materials. There are few named lakes and no major rivers in the Ecoregion.
Vegetation
Stunted black spruce forests with Labrador tea-feathermoss understories, black spruce bogs, horizontal fens, and peat plateaus are widespread on wet, poorly-drained sites. Warmer and better drained slopes, hummocky and ridged landforms, and coarse-textured materials are sites where more vigourous and diverse mixed-wood, deciduous and conifer stands are locally abundant. Elsewhere, upland forests are restricted to relatively small areas. Black spruce forests, bogs and peat plateaus are more extensive than in the Taiga Plains MB Ecoregion. Northern ribbed fen and horizontal fen development is also different between these two Level III ecoregions; plant growth is not as vigourous and larch is less common on fens in the Taiga Plains HB Ecoregion.
Ecoregions
The following are the smaller ecoregions within the Taiga Plains High Boreal Ecoregion:
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Ebbutt Upland HB Ecoregion
Horn Plain HB Ecoregion
Sibbeston Upland HB Ecoregion
Trout Upland HB Ecoregion
Cameron Upland HB Ecoregion
Great Slave Plain HB Ecoregion
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Click here for more information on the Taiga Plains High Boreal Ecoregion and all of the ecoregions within it.
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Total area: 42,101 km2 (9% of Taiga Plains)
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