This ecoregion lies predominantly within the Yukon Territory. A small portion dips into extreme northwestern British Columbia. This ecoregion contains much of the human population in the Yukon, including parts of most major highways in the territory.
The climate in this ecoregion in the Yukon interior can be characterized as cold and semiarid. Mean annual temperature is around -3°C, mean summer temperature is 11°C, and mean winter temperature ranges between -16.5°C and -19°C. The southern portion of the ecoregion lies within the rain shadow of the St. Elias Mountains. Mean annual precipitation is in the range of 225-400 mm, increasing with elevation and in the north-east (ESWG 1995).
The Yukon Plateau is the dominant physiographic feature. It is composed of groups of rolling hills and plateaus separated by deeply cut, broad valleys. Elevations in this ecoregion are generally above 1000 m asl, with some smaller peaks in the south. Low-ice-content permafrost occurs in a sporadic discontinuous pattern here (ESWG 1995).
White and black spruce (Picea glauca and P. mariana) form the most common forest types. Lodgepole pine (P. contorta) often invades very dry sites and burnt areas. South-facing slopes at low elevations are often characterized by grassland communities. Scrub birch (Betula sp.) and willow (Salix spp. ) occur up to the tree line, which is usually defined by the presence of alpine fir (Abies lasocarpa). In the colder alpine regions, mountain avens (Dryas hookeriana), dwarf shrubs, forbs, grasses, and lichens constitute the main vegetative cover. Due to the relatively dry interior climate, forests are frequently renewed from recurring natural fires such that young successional communities are most common (ESWG 1995).
Characteristic wildlife species include caribou (Rangifer tarandus), moose (Alces alces), mountain goat (Oreamnos americanus), Stone’s and Dall’s sheep (Ovis dalli spp.), grizzly and black bear (Ursus arctos and U. americanus), wolf (Canis lupus), coyote (Canis latrans), beaver (Castor canadensis), ground squirrel (Spermophilus parryii), hare (Lepus spp.), raven (Corvus corax), ptarmigan (Lagopus spp.) and golden eagle (Aquila chrysaetos) (ESWG 1995).
This ecoregion contains one of the most northern areas on the continent with grassland communities. The juxtaposition of these grasslands with northern boreal forest creates an unusual association of plant communities.
Habitat Loss and Degradation
It is estimated that approximately 75 percent of the ecoregion remains intact. Most of the disturbed habitat is considered to be altered, with only a small amount of area heavily altered. Factors leading to habitat loss include forestry and mining activities, urban growth around Whitehorse, and major transportation corridors.
Remaining Blocks of Intact Habitat
Most of the ecoregion, particularly the uplands, can be considered as intact habitat. Valley bottoms have been most widely developed.
Degree of Fragmentation
Habitat fragmentation in this ecoregion has principally resulted from the construction of major transportation corridors through the lower elevations. Susceptibility is high for some species with seasonal migrations or movements between habitat types, especially large carnivores, woodland caribou and Dall’s sheep.
Degree of Protection
There are no large protected areas yet established in this ecoregion.
•Charlie Cole Creek Ecological Reserve - southern Yukon Territory - 1.62 km2
•Nisutlin River Delta National Wildlife Area (not fully protected) - southern Yukon Territory - 5.28 km2
Types and Severity of Threats
Threats to biodiversity are increasing rapidly in this ecoregion. Timber harvesting has begun and is yet to be well-regulated or planned in the Yukon. Mining activity is significant in some parts of the ecoregion and a number of wildlife species are in serious decline. A government-sanctioned wolf kill has been occurring in this area for the past few years.
Suite of Priority Activities to Enhance Biodiversity Conservation
•The highest priority activity is to establish a new protected area following the Kusawa Lake territorial park proposal.
•Control programs for carnivores should be permanently ended.
•Canadian Nature Federation
•Canadian Parks and Wilderness Society, Yukon Chapter
•Friends of Yukon Rivers
•World Wildlife Fund Canada
•Yukon Conservation Society
Relationship to other classification schemes
The Yukon Plateau-Central and the Yukon Southern Lakes (TEC 175 and 177) in the Boreal Cordillera ecozone correspond to the Yukon Interior Dry Forests (Ecological Stratification Working Group 1995) which include Rowe’s (1972) Dawson and Central Yukon Boreal forest regions (26b and c) and Tundra vegetation.
Prepared by: S. Smith, J. Peepre, K. Kavanagh, M. Sims, G. Mann.