This ecoregion at the southern foothills of the Mackenzie Mountains encompasses the South Nahanni River and Nahanni National Park. It has cool summers and very cold winters. The mean annual temperature is approximately -5°C. The mean summer temperature is 9°C and the mean winter temperature is -19.5°C. The mean annual precipitation ranges from over 400 mm in the east to 500 mm in the west. This ecoregion is classified as having a low subarctic ecoclimate. It is dominated by open stands of black spruce with an understory of dwarf birch, Labrador tea, lichen, and moss. Drier and warmer sites tend to have more white spruce, paper birch, and some aspen. Wet sites are usually covered with bog-fen vegetation such as dwarf black spruce, Labrador tea, ericaceous shrubs, and mosses. The ecoregion is underlain by Palaeozoic carbonates, and is incised by deep and narrow valleys. Many summits and hills are flat because of the attitude of the strata, but extensive remnants of former erosion surfaces are evident. Elevations are usually less than 1372 m asl, but some reach over 1800 m asl. Permafrost is extensive and discontinuous with low ice content, and some ice wedges are found along the southern border of the ecoregion. Dystric Brunisols, Turbic Cryosols, and Organic Cryosols are the dominant soils. This ecoregion provides important summer range for caribou, and breeding habitat for snow and Canada geese and other waterfowl. Other characteristic wildlife includes moose, grizzly and black bear, red fox, snowshoe hare, ground squirrel, wolf, lynx, weasel, and snowy owl. Land uses are limited to fishing, trapping, hunting, outdoor recreation, and tourism.
This ecoregion is part of the Taiga Plains ecozone.