Aspen parkland refers to a very large area of transitional biome between prairie and boreal forest in two sections, namely the Peace River Country of northwestern Alberta crossing the border into British Columbia, and a much larger area stretching from central Alberta, all across central Saskatchewan to south central Manitoba and continuing into small parts of the US states of Minnesota and North Dakota. [3] Aspen parkland consists of groves of aspen, poplar and spruce, interspersed with areas of prairie grasslands, also intersected by large stream and river valleys lined with aspen-spruce forests and dense shrubbery. This is the largest boreal-grassland transition zone in the world and is a zone of constant competition and tension as prairie and woodlands struggle to overtake each other within the parkland.[4]
This article focuses on this biome in North America. Similar biomes also exist in Russia north of the steppes (forest steppe) and in northern Canada.
Definitions
According to the Ecological Framework of Canada, published in 1999, the Aspen Parkland ecoregion (#156) is the largest and northernmost section of Prairies Ecozone.[5] This definition is the arc-shaped region (i.e. including the WWF's central and foothills parkland but excluding the Peace River region). Partly defined by climate, it had a mean annual temperature of approximately 1.5°C circa 1999, and rainfall varied from 400 to 500mm/annum. It includes the communities of Red Deer and Edmonton in Alberta; Lloydminster on the Alberta–Saskatchewan border; North Battleford, Saskatoon, Humboldt, and Yorkton in Saskatchewan; and Brandon, Manitoba as its major population centres and have a total population of 1.689 million. By this definition, there are approximately 5,500,000 hectares (14,000,000 acres) of this ecoregion in the province of Alberta.[6]
The aspen parkland biome runs in a thin band no wider than 500km through the Prairie Provinces, although it gets broader to the west, especially in Alberta. This is a hilly landscape with many small lakes and ponds. The cities of Edmonton and Saskatoon are the largest cities completely in this biome while Winnipeg is bordered by tallgrass prairie to the west and south and the aspen parkland to the northeast, and Calgary is bordered by prairie to the east and the Foothills Parkland to the west.
There are three main sections of aspen parkland: Peace River, Central, and Foothills. The Central Parkland is the largest section and is part of main band of aspen parkland extending across Alberta, Saskatchewan and Manitoba, bordered by prairie to the south and the boreal forest to the north. The Peace River Country is located along the Peace River region of the province, extending across the border into northeastern British Columbia, and is completely surrounded by boreal forest, cutting it off from the Central Parkland, it extends as far north as Fort Vermilion at 58°N 116°W. The Foothills parkland covers the Foothills of the Rocky Mountains as far south as Waterton Lakes National Park.[8][9]
Climate
The region has a humid continental climate accompanied by a subhumid low boreal transitional grassland ecoclimate.[2] Summers are warm and short and winters can be long and cold. The mean annual temperatures range from 0.5 to 2.5°C (32.9 to 36.5°F), with summers ranging 13 to 16°C (55 to 61°F), and winters ranging −14.5 to −12.5°C (5.9 to 9.5°F). The Peace River Country in northwestern Alberta and northeastern areas of the North Interior in British Columbia has the coolest climate, but still supports extensive farmland. Southwest Manitoba sees the warmest. Annual precipitation is usually between 375 to 700 millimetres (14.8 to 27.6in).[2]Chinook winds off the foothills also occur in winter, mainly affecting Alberta.[citation needed]
The Populus tremuloides ("trembling" or "quaking" aspen) is the dominant tree species of the parkland belt. Shown here in fall colours in west of Saskatoon, Saskatchewan.
Four significantly different habitats are common in the aspen parklands: The fescue prairie, the woodlands, the ravines and the wetlands and lakes. A rarer habitat type, tallgrass aspen parkland, occurs only in the extreme southeastern corner of the aspen parklands biome (southeastern Manitoba/northwestern Minnesota).[10] The fescue prairie is a meadowland rich in vegetation variety which forms the cover for the development of the richer soils that underlie the parklands. The close association with woodlands and wetlands makes this a choice location for many plants and a preferred range or home site for a wide diversity of wildlife. The richer soil and increased precipitation favours the natural growth of fescue grass, but varying conditions such as moisture level and grazing pressures allow for the invasion of secondary plant species.
There are numerous grasses and sedges in the fescue prairie. Gravelly and rocky terrain is a good location for parry oat grass. Dry areas favour June, porcupine and spear grass. Wet areas are often covered with slender wheat grass and timber oat grass. Prairie rose and snowberry are common shrubs found in these grasslands. Woody plant encroachment is widespread in the parklands.[11][12]
The forested, or woodlands area is dominated by trembling aspen (Populus tremuloides), balsam poplar (Populus balsamifera), other poplars and spruces, although other species of trees including paper birch (Betula papyrifera) do occur. Pines, mostly jack pine and lodgepole pine will often grow in areas that have sandy soil conditions. Other native species may include box elder, tamarack and willow, while the foothills area in the southeast of the region, such as Turtle Mountain or Spruce Woods Provincial Park, have woodland of white spruce and balsam fir but quaking aspen will dominate where the woodland has been cleared by fire. The proportion of forests to grasslands has increased somewhat over the prairie in areas not affected by agriculture in the last 100 years. This increase is partly due to the reduction of prairie fires which used to destroy the new saplings on the fringes of the aspen groves. Also, it was a common practice for farmers to plant stands of trees as windbreaks.
Aspen woodlands support an extensive understory consisting of mid-sized and small shrubs, some herbs and ground cover. Spruce-dominated woodlands usually do not support a dense understory due to more acidic and nutrient-poor soils and a denser canopy, which reduces sunlight reaching the forest floor below. However, in areas where a mixture of aspen and spruce occur, a fairly dense understory can still thrive. The mixed wood understory, as it is called, supports the greatest diversity of forest wildlife in the aspen parkland.
Wetlands are very common in this biome, including lakes, shallow open water, marshes, and grassy wetlands. Glacial erosion has contributed to such features by creating depressions in which standing water can collect. In the larger depressions, permanent lakes or ponds of water remain. Many of the lakes have a saline character, thus most shore vegetation has a high tolerance of salty soils. These lakes are known as alkali lakes. Wet meadows are flooded in the spring and dry by fall. They contain rushes, sedges and grasses and provide excellent opportunities to study the similarities and differences of these forms of vegetation.
Rivers and streams erode valleys throughout the parkland ecoregion. Steep hills and ravines result in a unique topography. Southwest slopes with increased exposure to the sun are dry and often more grass covered, while the shaded north and east exposures retain more moisture and tend to have greater forest cover. Some forms of vegetation unique to the ravines include: poplar, spruce, birch, willow, and river alder.
There are three main factors which influence the understory vegetation in the aspen stands of the mixed wood forest.
1. Good sun exposure encourages a dense vegetation growth below the canopy. This is of particular importance in the early spring before the trees are in leaf.
2. Warm soil and air temperature at the base level result in rapid melting process in spring which favours the growth of shrubs.
3. A large percentage of precipitation passes through the canopy. This provides a protective snow cover in winter and in warm seasons precipitation percolates through the leaf cover to nourish plants which require surface soil moisture.
The mineral soil is covered by a decaying cover of organic matter. Numerous consumers and decomposers create humus materials. Burrowing animals mix the new fertile materials with the soil to form a rich rooting compound.
The spruce forest understory
Factors which influence the understory vegetation of spruce stands in the boreal forest association include:
1. Year round reduced sun exposure below the canopy restricts the forest undergrowth to shade tolerant species.
2. A large percentage of the precipitation is trapped in the upper tree boughs of the spruce forest and is released through evaporation. The ground cover of feather moss quickly absorbs most of the moisture which does penetrate the canopy. These factors combine to cause drier conditions in the underlying mineral soils.
3. The fallen acidic spruce needles are not fully decomposed and combine with the moss base. Water held in the moss carries the acid from the spruce needles into the mineral soil and leaches out soil nutrients – leaving a highly acidic, low nutrient soil base which is unsuitable for most boreal vegetation.
As a result of the above factors the forest floor ranges from nearly devoid of vegetation to a dense carpet of feather moss. A sparse community of shade tolerant shrubs exists in this environment. Some species of plants in the understory are Green Alder, low bush cranberry, prickly rose, bunchberry, twinflower, wild lily-of-the-valley, northern Comandra and wintergreens.
There are several factors which influence the mixedwood stands in the boreal forest.
Where there are stands of aspen and spruce forests in close association with each other, a mixed wood forest occurs. Each group forms its own microassociation as described previously.
When the spruce and aspen forest types are mixed, the result can be quite different from the aspen or spruce stands. Animal and vegetation associations from each type combine to create considerable diversity of habitat which is typical of either spruce or aspen stands. The mixture of the transition soils provides an attractive environment with either pure spruce or pure aspen woodlands. An example of a bird which prefers a mixed wood habitat is the yellow-rumped warbler.
The mixedwood forest wetlands consist mainly of bogs, fens and marshes. Black spruce, tamarack, willow and bog and sphagnum mosses are the major vegetation types found in these lowlands. Dwarf birch and sedges cover large, wet areas with jack pine occurring on the sandy ridges.
For boreal aspen stands less than 40 years old, Comeau (2002)[13] found that basal area provided a useful general predictor of understorey light levels, but, on the basis of light measurements in one 80-year-old stand, cautioned that relationships between understorey light and basal area may not hold in older stands. The literature indicates that the height growth of understorey spruce should be maximized when light levels exceed 40% or when aspen basal area is less than 14 m2/ha. Models developed by Wright and others in 1998 show radial growth of understorey white spruce increasing almost linearly with increasing light and a continuous decline in radial increment with increasing aspen basal area.[14] When applied to Comeau's 2002 data,[13] the Wright models suggest that spruce mortality will remain very low until aspen basal area exceeds 20 m2/ha, above which mortality will increase rapidly.
Burrowing rodents such as Richardson's ground squirrels, thirteen-lined ground squirrels, and pocket gophers play a major role in the balance between the aspen groves and the grassland. These excavators make mounds of fresh soil which are ideal locations for the germination of poplar seeds. Once established, these trees spread by suckering, thus creating a new aspen groves.
White-tailed deer finds shelter in the aspen and graze on the grasslands; coyotes and foxes hunt the resident rodents. Historically, bison grazed on the grassland and helped to prevent the spread of aspen groves. However, bison are now mostly absent due to over hunting during settlement in the 19th century and extensive loss of habitat due to agriculture. Bison, however, can still be seen in protected areas such as Elk Island National Park east of Edmonton and in farms, where they are raised for meat. Boreal woodland caribou(Rangifer tarandus caribou) also used to roam the Parkland, especially the Peace region, but were hunted out of the area.
Wildlife in the woodlands is varied and abundant. The varying hare, weasel, fox, coyote, and white-tailed deer make their homes in this region, while water dependent mammals who make the ravines and wetland areas of the ecoregion their home are beaver, muskrats, otters and mink.
Extensive cultivation has disturbed the habitats of some birds which nest and feed on the fescue grassland. However, the horned lark and meadowlark have managed to adapt to the new conditions. Song sparrow, vesper sparrow, and American goldfinch can often be seen in open areas.
The invertebrate population in the woodland is enormous. Some of the most common invertebrates are roundworms, snails, segmented worms, centipedes, mites, spiders and mosquitoes. Paranthrene dollii and forest tent caterpillars are destructive to the tree cover. Insects of the wetlands in this region include caddis flies, mayflies and black flies.
Human use, threats and conservation
The mixture of small patches of trees near rivers and patchworks of farm fields are typical of parkland. Shown here is the North Saskatchewan River in Alberta circa 2008.Aspen groves surrounded by cultivated fields of wheat near Saskatoon, Saskatchewan
Before European colonization, there were large areas of western aspen and aspen parkland in the west of what would become Canada and the United States. This was maintained by light to moderate fires with a frequency of 3 to 15 years. Fire also swept the Rocky Mountains aspen as frequently as every ten years, creating large areas of parkland. Settlement increased fire frequency in the late 19th century until fire suppression became popular.[15]
Most of the aspen parkland, like the prairie biome, has been extensively altered by agriculture over the last 100 years since settlement first began in the late 19th century. While the climate is generally cooler than in the prairies, the climate is still mild and dry enough to support large-scale farming of crops such as canola (Brassica napsus), alfalfa (Medicago sativa) and wheat (Triticum aestivum), and livestock grazing. The soils in the aspen parkland biome are also quite fertile, especially around Edmonton and Saskatoon. Oil and natural gas exploration and drilling have also disturbed the natural habitat, especially in Alberta and northeastern British Columbia. As a result, less than 10% of the original habitat remains.[citation needed]
The First Nations of this region were not solely buffalo-huntingnomads, as were tribes to the south. They also relied to a great extent on trapping (rabbits, etc.) fishing, and deer and moose hunting, as well as gathering parkland berries, such as the Saskatoon berry or the high bush cranberry.
This area was one of the most important regions of the fur trade in North America. Both the Assiniboine and North Saskatchewan rivers were major fur trade routes, with a number of fur trade posts, much more so than rivers to the prairie south. The Métis people were formed around these posts from the intermarriage of white fur traders and native trappers.
Once European settlement began, this region was desired by the peasant farmers of Eastern Europe and the smallholders of Quebec for its wooded land, so that they could build and heat their own homes. This is as opposed to the primarily British and American settlers, who desired grasslands that were easier to break and plough. At the time, people of similar backgrounds were allowed to concentrate into block settlements by the federal government: for example the Edna-Star colony in Alberta, the largest concentration of Ukrainians on the prairies.
As a result of these different styles of indigenous hunting agricultural settlement, the ethnic makeup of the Prairie Provinces is somewhat divided north and south. Cree, Métis, French, and Ukrainian Canadians are concentrated in the parkland belt, and in parkland cities such as Edmonton, Saskatoon, and Winnipeg as opposed to prairie cities like Calgary and Regina, which were settled more so by people of Blackfoot, Sioux, American, English, and German backgrounds.
Taiga or tayga, also known as boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruces, and larches. The taiga or boreal forest is the world's largest land biome. In North America, it covers most of inland Canada, Alaska, and parts of the northern contiguous United States. In Eurasia, it covers most of Sweden, Finland, much of Russia from Karelia in the west to the Pacific Ocean, much of Norway and Estonia, some of the Scottish Highlands, some lowland/coastal areas of Iceland, and areas of northern Kazakhstan, northern Mongolia, and northern Japan.
Alberta is one of the thirteen provinces and territories of Canada. Located in Western Canada, the province has an area of 661,190 km2 (255,290 sq mi) and is bounded to the south by the United States state of Montana along 49° north for 298 km (185 mi); to the east at 110° west by the province of Saskatchewan for 1,223 km (760 mi); and at 60° north the Northwest Territories for 644 km (400 mi). The southern half of the province borders British Columbia along the Continental Divide of the Americas on the peaks of the Rocky Mountains, while the northern half borders British Columbia along the 120th meridian west. Along with Saskatchewan it is one of only two landlocked provinces or territories.
The Canadian Prairies is a region in Western Canada. It includes the Canadian portion of the Great Plains and the Prairie provinces, namely Alberta, Saskatchewan, and Manitoba. These provinces are partially covered by grasslands, plains, and lowlands, mostly in the southern regions. The northernmost reaches of the Canadian Prairies are less dense in population, marked by forests and more variable topography. If the region is defined to include areas only covered by prairie land, the corresponding region is known as the Interior Plains. Physical or ecological aspects of the Canadian Prairies extend to northeastern British Columbia, but that area is not included in political use of the term.
Rangelands are grasslands, shrublands, woodlands, wetlands, and deserts that are grazed by domestic livestock or wild animals. Types of rangelands include tallgrass and shortgrass prairies, desert grasslands and shrublands, woodlands, savannas, chaparrals, steppes, and tundras. Rangelands do not include forests lacking grazable understory vegetation, barren desert, farmland, or land covered by solid rock, concrete, or glaciers.
The tallgrass prairie is an ecosystem native to central North America. Historically, natural and anthropogenic fire, as well as grazing by large mammals provided periodic disturbances to these ecosystems, limiting the encroachment of trees, recycling soil nutrients, and facilitating seed dispersal and germination. Prior to widespread use of the steel plow, which enabled large scale conversion to agricultural land use, tallgrass prairies extended throughout the American Midwest and smaller portions of southern central Canada, from the transitional ecotones out of eastern North American forests, west to a climatic threshold based on precipitation and soils, to the southern reaches of the Flint Hills in Oklahoma, to a transition into forest in Manitoba.
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 geography of Saskatchewan is unique among the provinces and territories of Canada in some respects. It is one of only two landlocked regions and it is the only region whose borders are not based on natural features like coasts, lakes, rivers, or drainage divides. The borders of Saskatchewan, which make it very nearly a trapezoid, were determined in 1905 when it became a Canadian province. Saskatchewan has a total area of 651,036 square kilometres (251,366 sq mi) of which 591,670 km2 (228,450 sq mi) is land and 59,366 km2 (22,921 sq mi) is water.
The Boreal Plains Ecozone, as defined by the Commission for Environmental Cooperation (CEC), is a terrestrial ecozone in the western Canadian provinces of Manitoba, Saskatchewan and Alberta. It also has minor extensions into northeastern British Columbia and south-central Northwest Territories. The region extends over 779,471 km2, of which 58,981 km2 is conserved.
The Prairies Ecozone is a Canadian terrestrial ecozone which spans the southern areas of the Prairie provinces of Alberta, Saskatchewan, and Manitoba. It is a productive agricultural area, and is commonly referred to as "Canada's breadbasket". Farmland covers about 94% of the land, and is the dominant domestic economic activity of the zone, as well as an important factor in Canadian foreign trade. Natural gas and oil are abundant in the area. The corresponding Level II ecoregion of the US Environmental Protection Agency is the Great Plains Ecoregion.
Canada's boreal forest is a vast region comprising about one third of the circumpolar boreal forest that rings the Northern Hemisphere, mostly north of the 50th parallel. Other countries with boreal forest include Russia, which contains the majority; the United States in its northernmost state of Alaska; and the Scandinavian or Northern European countries. In Europe, the entire boreal forest is referred to as taiga, not just the northern fringe where it thins out near the tree line. The boreal region in Canada covers almost 60% of the country's land area. The Canadian boreal region spans the landscape from the most easterly part of the province of Newfoundland and Labrador to the border between the far northern Yukon and Alaska. The area is dominated by coniferous forests, particularly spruce, interspersed with vast wetlands, mostly bogs and fens. The boreal region of Canada includes eight ecozones. While the biodiversity of regions varies, each ecozone has characteristic native flora and fauna.
The Willamette Valley ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency in the U.S. states of Oregon and Washington. Slightly larger than the Willamette Valley for which it is named, the ecoregion contains fluvial terraces and floodplains of the Willamette River system, scattered hills, buttes, and adjacent foothills. It is distinguished from the neighboring Coast Range, Cascades, and Klamath Mountains ecoregions by lower precipitation, lower elevation, less relief, and a different mosaic of vegetation. Mean annual rainfall is 37 to 60 inches, and summers are generally dry. Historically, the region was covered by rolling prairies, oak savanna, coniferous forests, extensive wetlands, and deciduous riparian forests. Today, it contains the bulk of Oregon's population, industry, commerce, and agriculture. Productive soils and a temperate climate make it one of the most important agricultural areas in Oregon.
The Eastern Cascades Slopes and Foothills ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the U.S. states of Oregon, Washington, and California. In the rain shadow of the Cascade Range, the eastern side of the mountains experiences greater temperature extremes and receives less precipitation than the west side. Open forests of ponderosa pine and some lodgepole pine distinguish this region from the Cascades ecoregion, where hemlock and fir forests are more common, and from the lower, drier ecoregions to the east, where shrubs and grasslands are predominant. The vegetation is adapted to the prevailing dry, continental climate and frequent wildfire. Volcanic cones and buttes are common in much of the region.
The Blue Mountains ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the Pacific Northwest, mainly in the state of Oregon, with small areas over the state border in Idaho and southeastern Washington. It is also contiguous with the World Wildlife Fund's Blue Mountain forests ecoregion.
The Klamath Mountains ecoregion of Oregon and California lies inland and north of the Coast Range ecoregion, extending from the Umpqua River in the north to the Sacramento Valley in the south. It encompasses the highly dissected ridges, foothills, and valleys of the Klamath and Siskiyou Mountains. It corresponds to the Level III ecoregion designated by the Environmental Protection Agency and to the Klamath-Siskiyou forests ecoregion designated by the World Wide Fund for Nature.
The Northern Basin and Range ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the U.S. states of Oregon, Idaho, Nevada, Utah, and California. It contains dissected lava plains, rolling hills, alluvial fans, valleys, and scattered mountain ranges in the northern part of the Great Basin. Although arid, the ecoregion is higher and cooler than the Snake River Plain to the north and has more available moisture and a cooler climate than the Central Basin and Range to the south. Its southern boundary is determined by the highest shoreline of Pleistocene Lake Bonneville, which once inundated the Central Basin and Range. The western part of the region is internally drained; its eastern stream network drains to the Snake River system.
The native flora of Saskatchewan includes vascular plants, plus additional species of other plants and plant-like organisms such as algae, lichens and other fungi, and mosses. Non-native species of plants are recorded as established outside of cultivation in Saskatchewan, of these some non-native species remain beneficial for gardening, and agriculture, where others have become invasive, noxious weeds. Saskatchewan is committed to protecting species at risk in Canada. The growing season has been studied and classified into plant hardiness zones depending on length of growing season and climatic conditions. Biogeographic factors have also been divided into vegetative zones, floristic kingdoms, hardiness zones and ecoregions across Saskatchewan, and natural vegetation varies depending on elevation, moisture, soil type landforms, and weather. The study of ethnobotany uncovers the interrelation between humans and plants and the various ways people have used plants for economic reasons, food, medicine and technological developments. The Government of Saskatchewan has declared 3 indigenous plants as provincial symbols.
The Fauna of Saskatchewan include several diverse land and aquatic animal species. From the multiplicity of invertebrates and vertebrates, two have been chosen as symbols of Saskatchewan. Cenozoic vertebrate fossils reveal the geological evolution of the interior plains and its prehistoric biogeography. Today, Saskatchewan's ecosystems range from the sub-arctic tundra of the Canadian Shield in north Saskatchewan to aspen parkland, the Mid-Continental Canadian forests in the centre of the province and grassland prairie. Fauna inhabit areas unique to their own specific and varied breeding, foraging and nesting requirements. With a large land and water area, and small population density, the ecoregions of Saskatchewan provide important habitat for many animals, both endangered and not. Naturalists observing wildlife have enumerated shrinking and growing wildlife populations. They advocate programs and methods to preserve or re-introduce endangered species and identify programs of control for outbreaks of wildlife populations. A broad diversity of wildlife habitats are preserved as parks and reserves protecting the feeding and breeding grounds of protected and indigenous fauna of Saskatchewan.
The Midwest Canadian Shield Forests is an ecoregion in Canada, classified as a Taiga and Boreal Forests Biome.
The Canadian Aspen Forests and Parklands is one of 844 terrestrial ecoregions defined by One Earth. This ecoregion includes parts of the Canadian provinces of Alberta, Saskatchewan, and Manitoba, north-central and eastern North Dakota, most of east South Dakota, and north-central Nebraska in the American Great Plains. The United States Environmental Protection Agency (EPA) defines this ecoregion as the Northern Glaciated Plains.
Grizzly Ridge Wildland Provincial Park is a wildland provincial park in northern Alberta, Canada. The park was established on 14 April 1999 and has an area of 10,706.07 hectares. The park is included in the Upper Athabasca Region Land Use Framework.
↑ Wright, E. F.; Coates, K. D.; Canham, C. D.; Bartemucci, P. (1998). "Species variability in growth response to light across climatic regions in northwestern British Columbia". Canadian Journal of Forest Research. 28 (6): 871–886. doi:10.1139/x98-055.
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