This ecoregion extends from Lake Laberge south to the boundary with British Columbia. The ecoregion covers parts of the Lewes and Nisutlin plateaus and all of the Teslin Plateau. The climate is cold and semiarid. Within major valleys the mean annual temperature is approximately -2.5°C with a summer mean of 10°C and a winter mean of -16.5°C. Lying within the rain shadow of the St. Elias Mountains, mean annual precipitation ranges 225-300 mm in the major valleys. Boreal forests are composed of open white spruce and lodgepole pine intermixed with aspen. South-facing slopes at low elevation are occupied by grassland communities. Subalpine elevations above 1200 m asl support open forest communities of alpine fir, white spruce and occasionally lodgepole pine. The forests suffer frequently from recurring natural fires such that seral communities are most common. Mountain avens, dwarf shrubs, forbs, grasses, and lichens constitute the main vegetative cover in colder, more exposed alpine sections. Most of the terrain lies 600-1500 m in elevation, but a few peaks are over 1800 m asl. Underlain by Mesozoic sedimentary strata and Palaeozoic metamorphic slates, schists, the topography is characterized by dissected plateaus and rolling hills. Eutric Brunisolic soils on sandy loam and rolling morainal to steep colluvial material are dominant. Low ice content permafrost occurs in a sporadic discontinuous pattern. Cryosolic soils are scattered throughout the landscape on some poorly drained areas and on north-facing slopes. Representative wildlife includes mountain goat, Stone's and Dall's sheep, grizzly bear, moose, ptarmigan, wolf, coyote, ground squirrel, and caribou. Land uses include hunting, trapping, and recreation values in alpine and subalpine regions, whereas forestry and forage-based agricultural activities occur in warmer, lower valleys below 850 m asl elevation. Whitehorse and Teslin are the major communities. The population of the ecoregion is approximately 20 900.
This ecoregion is part of the Boreal Cordillera ecozone.