Terrestrial Ecozones, Ecoregions and Ecodistricts of Manitoba

Terrestrial Ecozones, Ecoregions, and Ecodistricts of Manitoba An Ecological Stratification of Manitoba’s Natural Landscapes Research Branch Technical Bulletin 1998-9E R.E. Smith, H. Veldhuis, G.F. Mills, R.G. Eilers, W.R. Fraser, and G.W. Lelyk Land Resource Unit Brandon Research Centre, Research Branch Agriculture and Agri-Food Canada Boreal Shield Ecozone Churchill River Upland Ecoregion Boreal Shield Ecozone The Boreal Shield Ecozone is the largest ecozone in Canada, extending as a broad inverted arch from northern Saskatch- ewan east to Newfoundland, passing north and east of Lake Winnipeg and north of the Great Lakes and the St. Lawrence River. Although in Manitoba, this ecozone covers more area than any other, the Manitoba portion represents only a small part of the vast extent of this ecozone. Climate The ecozone has a strong continental climate which is char- Precipitation increases from west to east. Mean annual acterized by long, cold winters and short, cool summers precipitation is about 400 mm in northern Saskatchewan in the west, and long, cold winters, but short, warm sum- and about 1000 mm in Quebec and Labrador, and up to mers in the east. These climatic conditions are somewhat 1600 mm in parts of Newfoundland. The soil climate modified by maritime influences along the coastal regions ranges from humid, cold Cryoboreal in the northwestern in Atlantic Canada and the moderating effect of the Great half to perhumid, moderately cool Boreal in the eastern Lakes in central Ontario. The mean annual temperature section. ranges from about -4oC in northern Saskatchewan to 5.5oC in Newfoundland. Selected Climate Data (Annual Means) for the Boreal Shield Ecozone West of the Great Lakes Station Temperature Precipitation Degree Frost Free (oC) Days Period Rain (mm) Snow (cm) Total (mm) (>50C) (days) Stony Rapids2 -4.5 249.6 127.4 376.7 1006 71 Flin Flon A1 -0.5 345.3 143.9 484.1 1379 115 Thompson A1 -3.4 351.6 200.9 535.6 1038 59 Pinawa WNRE1 1.9 429.0 129.5 558.5 1665 110 Dryden A2 1.6 527.4 170.8 697.5 1610 125 1 Canadian Climate Normals, 1961-1990. Atmospheric Environment Service, Environment Canada. 2 Canadian Climate Normals, 1951-1980. Atmospheric Environment Service, Environment Canada. 59 Boreal Shield Ecozone Churchill River Upland Ecoregion Plate BS1. Peat plateau bog. Bog and fen peatlands are widespread throughout the Boreal Shield Ecozone. A peat plateau bog is a permanently frozen peatland that has permafrost at about 60 cm below the surface by the end of summer. The permafrost is ice-rich and extends into the underlying mineral materials. Peat plateau bogs often occur as islands surrounded by non- frozen fen, and are raised about 100 cm above the surrounding terrain. They are generally flat with a hummocky sphagnum moss surface. Low ericaceous shrubs such as Labrador tea are common and the open tree cover consists of stunted black spruce. Plate BS2. Crowning wildfire. Wildfire is a frequent event in the Boreal Shield Ecozone. As a result the forest cover consists of a mosaic of stands of different ages, bedrock outcrops and wetlands. Upland stands are usually less than 150 years old. Older forest is generally found on peatlands and in areas protected by lakes (peninsulas and islands). Wildfires are an integral part of the boreal forest ecosystem and are the major agent in forest renewal. The wildfire in the photo occurred in the Wrong Lake area following a lightning storm. Within a few days the fire had expanded, moving both on the ground and through the tree tops. 60 Boreal Shield Ecozone Churchill River Upland Ecoregion Plate BS3. Jack pine on bedrock. Extensive areas of the Boreal Shield Ecozone are dominated by Precambrian bedrock that is only sparsely covered by thin mineral and organic deposits. After wildfire, jack pine is usually the dominant tree on these sites. It grows in the shallow and deep pockets of mineral soil occurring in small depressions and cracks in the bedrock surface. Black spruce may become part of the mix after some time on sites with deeper soil materials, or where runoff water collects. Plate BS4 Pisew Falls. Pisew Falls on the Grass River is the largest accessible falls in Manitoba and is located in a provincial park between Setting Lake and Paint Lake. The area near the falls has a more moderate and humid climate than the surrounding upland due to the spray from the falls. Large white spruce and balsam fir dominate the forest along the slopes, while only a short distance away the forest consists of black spruce. 61 Boreal Shield Ecozone Churchill River Upland Ecoregion Plate BS5. Permafrost in veneer bog. Veneer bogs are shallow peatlands that develop on gentle slopes and in depressions in areas of medium and fine textured surficial deposits. Permafrost develops where the peat layer provides sufficient insulation to prevent complete melting of seasonal frost. Thickness of the permafrost ranges from less than 100 cm to several metres. The photo shows the permafrost occurring in the highly decomposed organic layer below an insulating layer of nondecomposed sphagnum peat. The underlying mineral material is frozen glaciolacustrine clay. Plate BS6. Palsa bog in fen. Palsas are ice-cored peatlands. They may be raised several metres above the surrounding fen and are usually less than 100 m in diameter. They are formed when ice lenses develop in the peat and in the underlying mineral materials elevating the surface. They are common in the northern part of the glacial Lake Agassiz basin. 62 Boreal Shield Ecozone Churchill River Upland Ecoregion Plate BS7. Fen-bedrock complex. The lower- lying terrain in the foreground is a deep horizontal and string fen peatland. The upland areas are Precambrian bedrock outcrops, with shallow sandy till or clayey glaciolacustrine deposits. This type of landscape is common in the western part of the Manitoba portion of Ecoregion 90. Plate BS8. Black spruce stand. Black spruce stands with an extensive groundcover of feather mosses are common on the clayey sediments of the northern and central portions of the glacial Lake Agassiz basin. 63 Boreal Shield Ecozone Churchill River Upland Ecoregion Plate BS9. Orthic Gray Luvisolic soil on clayey glaciolacustrine sediment. These soils are moderately well drained, and are characterized by a light gray, platy or granular surface horizon, underlain by a strongly structured, brown coloured B horizon enriched in clay. The parent material is varved glaciolacustrine clay, with a clay content commonly higher than 80%. Plate BS10. Jack pine stand on sandy and gravelly glaciofluvial deposit. Jack pine stands are dominant on sandy and gravelly soil materials. The groundcover is dominated by mosses and lichens, and ericaceous shrubs such as blueberry. These dry sites are prone to frequent wildfires. When moisture holding capacity is higher due to fine sandy or loamy layers in the subsoil, the jack pine stands are soon invaded by black spruce. 64 Boreal Shield Ecozone Churchill River Upland Ecoregion Plate BS11. Eluviated Dystric Brunisolic soil on sandy glaciolacustrine deposit. Eluviated Dystric Brunisols are commonly associated with sandy materials. They are characterized by a grayish upper horizon overlying a brownish B, slightly enriched in iron compounds. The upper 30 cm of the soil is strongly acid. Plate BS12. Bouldery till. The till derived from Precambrian Shield bedrock is sandy and contains abundant coarse fragments. Associated soils are Dystric Brunisols. 65 Boreal Shield Ecozone Churchill River Upland Ecoregion Surficial deposits and landforms Wildlife The ecozone is dominated by a broadly rolling mosaic of Characteristic mammals include woodland caribou, moose, uplands and lowlands. Precambrian granitic bedrock out- black bear, raccoon, marten, fisher, striped skunk, lynx, crops interspersed with ridged to hummocky discontinu- bobcat and eastern chipmunk. Representative birds include ous veneers and blankets of glacial moraine, fluvioglacial boreal owl, great horned owl, blue jay, white-throated spar- and colluvium are characteristic surface deposits. Small row and evening grosbeak. to large lakes are common throughout the ecozone. Land use Soils The ecozone supports extensive forestry and mining op- Because this ecozone is so large, the range of climatic erations. Water-oriented recreation is locally extensive. conditions and the variety of mineral and organic depos- Commercial fishing is important on large lakes, while its is consequently large as well, resulting in a wide vari- hunting and trapping are important activities throughout. ety of soils. Agriculture is limited and generally restricted to the southern part of the ecozone. In the northern parts of the ecozone, except for Newfound- land, permafrost is widespread, especially in organic de- There are four ecoregions within the Boreal Shield posits. As a result, Organic Cryosols, and to lesser extent Ecozone in Manitoba. Static and Turbic Cryosols, are important soil components. Organic soils, other than organic cryosols, are also widespread as extensive areas are covered by non-frozen peat deposits. Brunisols characterize coarse to medium textured materials in the northern and western sectors, while Hu- mic Ferric Podzols are dominant in the southern and eastern parts. Luvisolic and Gleysolic soils are generally associated with fine textured materials. Vegetation The well to imperfectly drained soils in this ecozone generally support closed, single-species forest stands, or mixed stands of white and black spruce, balsam fir and jack pine. Towards the south, there is a wider distribution of decidu- ous trees such as white birch, trembling aspen and balsam poplar, with yellow birch and sugar maple to the east. Or- ganic deposits support closed or open stands of black spruce or tamarack. Frequent forest fires in this ecozone have a profound effect on the composition and age distribution of forest stands. The contrasting areas of exposed bedrock, mineral soils, and peatlands throughout the ecozone create an intricate and varied mosaic of landscape elements.

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