Like the mountain-and-foothill region, Alberta’s plains also are made up of three different vegetation zones. Across Highway 2, east of the mountains and foothills, southeast Alberta is dominated by the prairie—a vast, dry region of grasslands. Just north of the prairie is the aspen parkland, a belt of forest that runs across central Alberta to the foothills and covers approximately 10 percent of the province. Finally, Alberta’s largest ecological zone by far, covering more than half of the province, is the boreal forest. It is located north of the aspen parkland and extends into the Northwest Territories to the tree line, where the tundra begins.
Prairie is the warmest and driest ecological zone, with an annual precipitation less than 750 millimeters (30 inches). This harsh climate can support trees only where water flows, so for the most part the prairie is flat or lightly undulating open grassland. Irrigation has made agriculture possible across much of the south, and the patches of native grasses such as rough fescue and grama are rapidly disappearing. Among the cultivated pastureland and seemingly desolate plains, flowers punctuate the otherwise ochre-colored landscape. Alberta’s floral emblem, the prickly wild rose, grows here, as do pincushion cactus, buckbrush (or yellow rose), and sagebrush. In river valleys, aspen, willow, and cottonwood grow along the banks.
The stands of large cottonwoods in Dinosaur Provincial Park were part of the reason this park was designated a UNESCO World Heritage Site. (The park is a good example of prairie habitat.) The Cypress Hills, which rise above the driest part of the province, contain vegetation not generally associated with the prairies, including spruce, aspen, a variety of berries, and the calypso orchid.
Unique to Canada, this area is a transition zone between the prairie grassland to the south and the boreal forest to the north. As the name suggests, trembling aspen (named for light, flattened leaves that “tremble” in even the slightest wind) is the climax species, but much of this zone has been given over to agriculture—its forests burned and its soil tilled. Scattered stands of aspen, interspersed with willow, balsam poplar, and white spruce, still occur, whereas areas cleared by early settlers now contain fescue grass. Flowering plants such as prairie crocus, snowberry, prickly wild rose, and lily of the valley decorate the shores of the many lakes and marshy areas found in this biome. Elk Island National Park, best known for its mammal populations, is an ideal example of this unique habitat.
Only a few species of trees are able to adapt to the harsh northern climate characteristic of this zone. The area is almost totally covered in forest, with only scattered areas of prairielike vegetation occurring in the driest areas. In the southern part of the boreal forest, the predominant species are aspen and balsam poplar. Farther north, conifers such as white spruce, lodgepole pine, and balsam fir are more common, with jack pine growing on dry ridges and tamarack also present. The entire forest is interspersed with lakes, bogs, and sloughs, where black spruce and larch are the dominant species. Like the trees, the ground cover also varies with latitude. To the south, and in the upland areas where aspen is the climax species, the undergrowth is lush with a variety of shrubs, including raspberries, Saskatoon berries, and buffalo berries. To the north, where drainage is generally poor, the ground cover is made up of dense mats of peat.
Most areas of boreal forest accessible by road have been affected by fire or development, but some areas of old growth can still be found. Highway 63, which ends in Fort McMurray, runs through pristine northern boreal forest. Sir Winston Churchill Provincial Park, on an island in Lac La Biche, hasn’t been burned for more than 300 years and supports stands of balsam fir up to 150 years old.
© Andrew Hempstead, from Moon Western Canada, 3rd Edition