Shrubsteppe | Washington Department of Fish & Wildlife

The shrubsteppe is an arid ecosystem found in Eastern Washington and other western states. As one of Washington’s most diverse ecosystems, shrubsteppe provides habitat for species found nowhere else in the state, such as the greater sage-grouse, sagebrush sparrow, and burrowing owl. With an estimated 80% of historic shrubsteppe lost or degraded to development and agriculture since the arrival of non-native settlers, protecting remaining shrubsteppe habitats is more important than ever.

Description and Range

Physical description

Shrubsteppe landscapes are dominated by rolling, grassy plains, or “steppe,” with an overstory of sagebrush and other woody shrubs. On the ground, a fragile community of microscopic organisms form the cryptobiotic crust, which locks in moisture and helps prevent erosion. Various habitat features such as streams, wetlands, rocky talus slopes, and canyons support a variety of plants and animals uniquely adapted to the harsh and sensitive shrubsteppe ecosystem.

Wildflowers on shrubsteppe — Shrubsteppe habitat in Eastern Washington

While Wyoming big sagebrush is the most widespread shrub in this ecosystem, other common shrubs include antelope bitterbrush, three-tip sagebrush, and stiff sagebrush. Common grasses include Idaho fescue, bluebunch wheatgrass, Sandberg bluegrass, Thurber's needlegrass, and needle-and-thread. Some shrubsteppe areas have a layer of algae, moss, or lichens which are part of the cryptobiotic crust. In areas with greater precipitation or on soils with higher moisture-holding capacity, shrubsteppe can also support a dense layer of flowering plants. Common and iconic groups of plants in the shrubsteppe include balsamroot, buckwheats, and lupines.

Of the 10.4 million acres of shrubsteppe that existed in Eastern Washington before European settlers arrived in the mid-19th century, only 20% remains. Many areas with deep-soil shrubsteppe (supporting Wyoming big sagebrush) were the first to be converted to agriculture. In addition, non-native grasses such as cheatgrass often dominate existing shrubsteppe, which eliminates most of the native shrub cover through altered fire cycles. Non-native grasses also provide little nutritional value for wildlife and are much more prone to burning. Although fire is a natural part of the shrubsteppe ecosystem, the presence of invasive grasses increases the frequency and intensity of wildfires, contributing to the continued decline of shrubsteppe habitat health.

Geographic range

Shrubsteppe landscapes extend from south-central British Columbia into Eastern Washington, Oregon, and California, through Idaho, Nevada, and Utah, and into western Wyoming and Colorado.

In Washington, shrubsteppe habitats are throughout the Columbia Plateau and into the surrounding higher elevations regions.

Species

Over 200 species of birds, 30 species of mammals, and numerous species of reptiles, amphibians, and insects live in and depend on Washington’s shrubsteppe. Look for mule deer, western fence lizards, burrowing owls, and northern Pacific rattlesnakes hiding amongst the sagebrush and bluebunch wheatgrass, which is the official state grass of Washington.

Mule deer in shrubsteppe habitat — Mule deer in shrubsteppe

Since remaining shrubsteppe habitat is often fragmented due to development, species that depend on large, intact shrubsteppe habitat, such as the sage thrasher and sagebrush sparrow, are disproportionally affected. Although sensitive species may still use small patches of shrubsteppe, these fragmented areas usually offer less effective breeding habitat and are more susceptible to invasive weeds.

Some species such as the greater sage-grouse require large areas of undisturbed shrubsteppe to survive, as they rely on big sagebrush for cover and as a year-round food source, and are highly sensitive to human disturbance, particularly during the breeding season. While not currently listed as an endangered species under the federal Endangered Species Act (ESA), the U.S. Fish and Wildlife Service says the greater sage-grouse may eventually be listed as endangered if shrubsteppe habitats continue to decline. The federally-endangered pygmy rabbit is another species that depends on the sagebrush and undisturbed deep soil of shrubsteppe landscapes.

Although many shrubsteppe-dependent species are on the decline, this ecosystem continues to support a rich array of species, including elk, deer, bighorn sheep, bats, rabbits, rodents, frogs, snakes, lizards, and birds. Streams running through otherwise arid shrubsteppe can support species not typically thought of as living in arid climates such as porcupines, beavers, and songbirds.

At-risk species

Greater sage-grouse (Centrocercus urophasianus)

Governmental agencies and nongovernmental organizations are attempting to restore populations of greater sage-grouse with the aid of land acquisition, habitat improvement, conservation programs, and translocations. Between 2004 and 2016, WDFW, Yakima Training Center, Yakama Nation, and others collaborated to translocate this species from other states (Nevada, Oregon, Idaho, and Wyoming) to augment existing populations in Washington.