Yukon Interior dry forests
The Yukon Interior Dry Forests represent a unique ecological region situated largely in the southern Yukon Territory of Canada and extending into northwestern British Columbia. Classified as a taiga or boreal forest, this ecoregion spans approximately 24,100 square miles (62,419 square kilometers) and features a dry sub-Arctic climate characterized by long, cold winters and short, cool summers. The landscape consists mainly of rolling uplands and plateaus, with elevations ranging from 1,969 to over 5,906 feet (600 to 1,800 meters), while about 75% of the biome remains intact.
Flora in the region is predominantly boreal-subalpine coniferous forest, including species like white and black spruce, lodgepole pine, and alpine fir. The area also supports diverse grassland communities and wetland vegetation. In terms of fauna, the Yukon Interior Dry Forests is home to a variety of mammals, including woodland caribou and moose, as well as numerous bird species, such as waterfowl and game birds.
Despite its ecological richness, the region faces threats from land use activities like forestry, mining, and urban expansion, compounded by climate change impacts. Conservation efforts are ongoing, but large protected areas are limited, with some small reserves established to safeguard specific habitats. The ecoregion holds cultural significance for local Indigenous communities, reflecting the rich biodiversity and ecological heritage of the Yukon.
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Subject Terms
Yukon Interior dry forests
Category: Forest Biomes.
Geographic Location: North America.
Summary: The Yukon interior dry forests host a diverse collection of plants; they also contain one of the northernmost grassland areas linked to the boreal forests.
The Yukon Interior Dry Forests ecosystem is located within the Yukon Plateau, corresponding in the north with the Yukon Plateau Central, and in the south with the Yukon-Southern-Lakes ecoregions of the Boreal Cordillera ecozone. Geographically, the Yukon interior dry forests are located predominantly in the southern portion of the Yukon Territory of Canada, with a small area extending into northwestern British Columbia.
The northern part of the ecosystem extends from Lake Laberge to the lower Stewart River, near Dawson. The southern part extends southward from Lake Laberge to the boundary of British Columbia, and includes the entire Teslin Plateau and parts of the Nisutlin and Lewes Plateaus. This southern region lies in the rain shadow of the St. Elias Mountains.
As a biome, the Yukon interior dry forests is classified as taiga, or boreal forest; it spans 24,100 square miles (62,419 square kilometers). The climate of the region is classified as dry sub-Arctic or boreal; this type of climate has long, cold winters and short, cool summers. The average annual temperature of the Yukon interior dry forests is around 27 degrees F (minus 3 degrees C). The winter temperature ranges from minus 2 to 2 degrees F (minus 17 to minus 19 degrees C), while the average summer temperature is 52 degrees F (11 degrees C). Annual precipitation is 9–16 inches (226–399 millimeters), with the higher elevations in the northeastern part receiving more precipitation.
The Yukon interior dry forests is composed of rolling uplands and nearly level plateaus that are separated by deeply and broadly cut U-shaped valleys. The biome makeup is 65 percent boreal-subalpine coniferous forest, around 25 percent alpine tundra, 5 percent lakes and wetlands, and 5 percent rocky ground. There are several small mountain groups scattered across the plateau. Most of the terrain of the biome lies at 1,969–4,921 feet (600–1,500 meters), with a few peaks reaching above 5,906 feet (1,800 meters). The Yukon Interior Dry Forests biome also features irregular, patchy, low-ice-content permafrost.
Eutric brunisols, an alkaline soil type, is the dominant soil of the ecoregion, and is found in the alpine zones and loose bodies of sediment, or colluviums, at the base of steep slopes. Cryosolic soils—which feature permafrost within 3.3–6.6 feet (1–2 meters) of the surface—are found beneath established forests on the base of northern-facing slopes and in some wetlands. Due to the ecoregion’s low precipitation and elevated calcium carbonate deposits, weathering of rocks and soils is limited.
Flora
The Yukon Interior Dry Forests biome is in large part a subalpine coniferous forest. Southern-facing slopes in the lower elevations, however, contain a diverse collection of grassland communities that include juniper, sagewort, rose, and Kinnikinnick (Arctostaphylos uva-ursi). Willows, shrub birch, sedge tussocks, shrubby cinquefoil, cowberry, Canada buffaloberry, and various peat mosses, or sphagnum, dominate the wetlands areas.
Trees of the subalpine areas above 3,937 feet (1,200 meters) are white and black spruce, lodgepole pine, and alpine fir, intermingled with quaking aspen and balsam poplar. White and black spruce are the most common trees, with black spruce more common in the wetter areas. White spruce typically forms the treeline; alpine fir or paper birch occasionally form the treeline.
Lodgepole pines are typically found in recently burned or very dry areas. Recurring natural fires have resulted in developing many seral communities, an intermediate stage prior to full climax forest status. In the upper treeline and subalpine area, shrub birch and willows are common. Trees in the subalpine areas—such as fir, mountain hemlock, whitebark pine, white spruce, and Englemann spruce—are stunted, crooked, bent, and twisted (krummholz).
Moving above the treeline, the weather is characteristic of the alpine climate. This alpine area lacks vegetation and is covered by ice, snow, and rocks, while the alpine areas with vegetation consist of lichens, herbs, moss, forbs, mountain blueberry and crowberry, grasses, dwarf shrubs, and mountain avens.
Fauna
The Yukon Interior Dry Forests biome supports an abundant number of mammalian species of the Yukon. Common mammals here include woodland caribou from the Ibex, Atlin, and Carcross-Squanga herds; moose; mountain goats; Dall’s and stone sheep; mule deer and elks; wood bison; Arctic ground squirrels and red squirrels; beavers; and snowshoe hares. There are also predators such as grizzly bears, black bears, gray wolves, cougars, coyotes, wolverines, foxes, lynxes, and martens.
Avian species, too, are abundant. Examples of waterfowl are the northern pintail; Canada goose; Pacific and common loon; and horned, pied-billed, and red-necked grebes. Frequently seen shorebirds include the common snipe, sora, American golden plover, semipalmated plover, lesser yellowlegs, semipalmated and pectoral sandpipers, and American coot. Game birds include willow ptarmigan and the spruce, sharp-tailed, and ruffed grouse. Other common birds are black-billed magpies, gray jays, boreal chickadees, common ravens, rusty blackbirds, three-toed woodpeckers, red-breasted nuthatches, Lapland longspurs, and Wilson’s warblers. The abundance of waterfowl, songbirds, shorebirds, and game birds attracts numerous winged predators, such as great horned owls, bald and golden eagles, Merlin’s and peregrine falcons, and gyrfalcons.
The only amphibians in the Yukon interior dry forests are western toads and wood and spotted frogs. The ecoregion has no reptiles.
Land Use and Conservation
Approximately 31,000 Yukon Territory residents live within these forests. Land uses in the alpine and subalpine area include hunting, trapping, tourism, and recreation. Lower valleys below 2,789 feet (850 meters) are used for forestry and forage-based agriculture. Mining operations are scattered throughout the ecoregion. It is estimated that 75 percent of the biome remains intact, with the upland areas being better preserved than the valley bottoms. The Yukon Interior Dry Forests biome is considered be ecologically vulnerable. Threats to biodiversity are forestry and mining activities, major transportation routes, and urban sprawl around Whitehorse. The Yukon government has discontinued its wolf-control program.
Climate change is likely to stress these forests by reducing the amount of available water and undermining soil structure by the accelerating melt of permafrost. This in turn, will add to concentrations of global greenhouse gasses.
Currently, there are no large protected areas in the Yukon interior dry forests. There are small areas, such as the Charlie Cole Creek Ecological Reserve, established in 1981 and located in British Columbia. This reserve is 400 acres (162 hectares). Another such area is the Nisutlin River Delta National Wildlife Area, established in 1998 in accordance with the Teslin Tlingit Council Final Agreement, and located in southern Yukon. This wildlife area is 13,541 acres (5,480 hectares) and is only partly protected. The proposed Kusawa Lake Territorial Park is currently a special management area, and negotiations are continuing between Canadian and tribal governments regarding its final status.
Bibliography
"The Boreal Forest–A Life Source." Yukon Wildlife Preserve, 12 Apr. 2021, yukonwildlife.ca/wildlife/the-boreal-forest-a-life-source/. Accessed 8 Aug. 2022.
Ecological Stratification Working Group. A National Ecological Framework for Canada. Ottowa, Ontario: Centre for Land and Biological Resources Research, 1996.
McKenzie, Don, David L. Peterson, and Jeremy Littell. “Global Warming and Stress Complexes in the Forests of Western North America.” Seattle, WA: USDA Forestry Service, 2007.
Ricketts, T., E. Dinerstein, D. Olson, C. Loucks, W. Eichbaum, D. DellaSalla, et al. Terrestrial Ecoregions of North America: A Conservation Assessment. Washington, DC: Island Press, 1999.