The Okanagan ecoregion lies in south-central British Columbia and north-central Washington and is approximately 8,842,466 hectares with about 65% of the ecoregion in British Columbia and 35% in Washington. In British Columbia, the ecoregion extends from the east slopes of the Cascade and Coast ranges east to the west slope of the Columbia Mountains. The ecoregion extends from the Cascade crest in the North Cascades of Washington east to the Selkirk Mountains, with the Columbia River roughly forming its southern boundary.
The ecoregion extends up the east slope of the Cascades into British Columbia and along the west slope of the Canadian Rockies to Kamloops, B.C. The Washington portion of the Okanagan ecoregion extends from the Cascade crest in the North Cascades east to the Selkirk Mountains. The southwestern border of the ecoregion follows Sawtooth Ridge northeast of Lake Chelan. The Methow and Okanogan valleys are included, as are the Okanogan Highlands east to the Colville and Spokane valleys. Approximately 14% of Washington is within this ecoregion. Less than 10% of the Washington portion had been converted to agricultural or urban use as of 1991 (Washington GAP, 1997). Development is concentrated in the Spokane, Colville, Methow and Okanagan valleys. The area includes Okanagan, Ferry, Stevens and part of Spokane counties.
Conifer forests dominate the mountain ridges and low hills in the ecoregion, while valleys and lowlands are often non-forested. The conifer forests are more open and less continuous, consisting of smaller stands, than are forests west of the Cascade crest and in the Canadian Rockies. Douglas-Fir and Ponderosa Pine form the ecoregion's characteristic forests. They transition to shrub-steppe in the low broad valleys in the eastern part of the ecoregion, and to grasslands in the western part. Subalpine Fir/Engelmann Spruce forests occur at higher elevations. Whitebark Pine, Lodgepole Pine and Subalpine Larch form parklands in the highest elevations, often associated with dry alpine or subalpine meadows. The moister forests are dominated by Douglas Fir, with Western Larch, Western White Pine or Quaking Aspen as common components. Historically, stand replacement fires occurred at irregular intervals from 10 years in the lowland foothills to 150 years or more at high elevations. Decades of fire suppression have resulted in a landscape composed of dense, fire-prone forests.
This rugged ecoregion incorporates the southeastern portions of the Cascade Mountains and Okanagan Range, which are some of the warmest and driest mountain ranges in British Columbia. Subalpine forests dominate the ecoregion and are composed of Engelmann Spruce, Subalpine Fir, and Lodgepole Pine forests, which occur between 1200 and 2000 m. Douglas-fir, occasional Ponderosa Pine, and Pine Grass parklands cover the major valley bottoms. The range of representative wildlife is wide and includes California Bighorn Sheep, Mountain Goat, Mule Deer, Black Bear, Cougar, Coyote, Bobcat, Grouse, California Quail, waterfowl, and rattlesnake. Land use reflects ecological stratification. Grazing, forage production, orchards, water-oriented recreation, and tourism are common at lower elevations, woodland grazing, forestry, hunting, and recreation at higher elevations.
The conservation status of the ecoregion's two main components is quite different. It is estimated that only about 20 per cent of the Okanagan Range section remains as intact habitat. Upper forest habitats have either been logged in the past or are slated for logging in the future, while many of the valley bottoms are under intensive pressure from agriculture and urban development. In the Cascade Mountains, however, nearly 70 per cent of the area is considered to remain as intact habitat.
The Okanagan ecoregional assessment is the product of a partnership initiated in 2003 to identify priority conservation areas in this ecoregion. The Nature Conservancy of Canada (NCC), The Nature Conservancy (TNC), and the Washington Department of Fish & Wildlife (WDFW) are the primary partners in this project. The Washington Natural Heritage Program, Department of Natural Resources (WNHP), and the British Columbia Conservation Data Centre (BCCDC) were major contributors of technical expertise and data. The project has also benefited from the participation of many other scientists and conservation experts as team members and expert reviewers.