As a transition zone between the Cascades and Rocky Mountains, the Columbia Highlands comprise a myriad of ecologically important habitats, many of which are vulnerable to development and underrepresented in Washington's wilderness system.
Fire and water have shaped the Columbia Highlands.
Low-intensity wildfires have regularly shaped the dry terrain of the eastern Columbia Highlands for centuries. Fires clear out shrubs and dead wood and leave behind thick-barked fire-resistant old-growth ponderosa pine, larch and Douglas fir. Fires also create openings in the forest for flower-rich meadows and aspen islands.
Slight changes in elevation, orientation, amount of sunlight, soil composition, and landform cause dramatic variations in moisture. Pacific Ocean weather systems wrung dry by the North Cascades by the time they reach the western edge of Columbia Highlands build up moisture again before they slam into the Rockies. The extreme western edge of the Columbia Highlands in the Kettle River Range receives as little as 10 inches of moisture a year, whereas, farther east, more than 50 inches of precipitation rain down on the Selkirk Mountains, the wettest spot in eastern Washington.
The result is a complex mosaic of habitats.
Grasslands and shrub-steppe blanket the warm, dry, lower elevations. As the elevation increases, open, parklike stands of ponderosa pine and Douglas-fir give way to a mixed-conifer forest of hemlock, grand fir, white pine and western larch. At the highest elevations, subalpine parklands of Engelmann spruce and subalpine fir thrive among the long-lasting snows of winter.
As a transition zone between the Cascades and Rocky Mountains, the Columbia Highlands provide perfect topography for a rich spectrum of plant and animal life. However, because just over 1% of Washington’s wilderness acres lie east of the Cascades, many of these uniquely "dry side" habitats remain underrepresented in the wilderness system.
When disturbances such as wildfire create an opening in the forest canopy, particularly on moist soils, “islands” of aspen colonize the area. Aspens provide habitat for numerous avian species, including ruffed grouse, Wilson’s warbler, and red-naped sapsucker. Dependant on frequent disturbances to take root, aspens have declined in the West following decades of fire suppression.
Arguably North America’s most invaluable tree in terms of wildlife use, aspens are also the most widespread tree on the continent, but this habitat is uncommon in Washington and currently under-represented in the wilderness system.
The Profanity roadless area along the Kettle Crest and other wild areas in the Columbia Highlands harbor small islands of aspen.
Massive thickets of bunchgrass and sagebrush blanket the hot, dry slopes of the Kettle Range. Shrub-steppe usually skirts the lower fringes of the ponderosa parkland, although fingers of sagebrush habitat sometimes jut up into the subalpine parkland. Beautiful sage meadows blanket the slopes of Columbia and Wapaloosie Mountains along the Kettle Crest.
Although shrub-steppe can appear austere, early spring brings a profusion of wildflowers; one species, the Okanogan flameflower, grows nowhere else in the world outside of isolated pockets of shrub-steppe in the Kettle Range and adjacent southern British Columbia. About two-thirds of Columbia Basin shrub-steppe has disappeared under plow and pavement since European settlers arrived.
Ponderosa pine and Douglas-fir are the most common evergreen trees in this habitat, which forms the lower tree-line zone in the Columbia Highlands. Drought and frequent low-intensity fires maintain a sparse understory, which is usually dominated by grasses and forbs.
An important wintering area for white-tailed deer, ponderosa parkland also provides habitat for white-headed woodpecker, flammulated owl, pygmy nuthatch and yellow-pine chipmunk. However, fire suppression and heavy grazing have altered this biologically rich habitat.
Below subalpine parkland and above the ponderosa pine zone lies the most diverse selection of conifers in the Northwest: Western red cedar, grand fir, Douglas-fir, white pine and western larch. This forest hosts an array of understory shrubs,including serviceberry, huckleberry, ninebark, and ocean spray. The diversity of cover and vegetation allow for a variety of wildlife.
Past logging practices have altered much of the once-wild mixed-conifer forests of the Columbia Highlands. Today, only a few untouched remnants can be found, and most of those natural forests are within the boundaries of roadless areas.
Reflecting maritime forests in terms of high moisture and low frequency and intensity of wildfires, subalpine parkland occurs throughout the highest reaches of the Columbia Highlands. Beargrass, kinnikinnick and heather surround islands of weather-battered subalpine fir, Engelmann spruce, lodgepole pine and whitebark pine.
Slow growth rates in these harsh conditions mean disturbances such as logging can have lasting effects.