Sheldon NWR, Nevada, USA Photograph by John Morrison   Western North America: Western United States Deserts and Xeric Shrublands   84,200 square miles (218,100 square kilometers) -- slightly larger than Idaho Critical/Endangered

· Wet ‘n’ Dry
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
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Wet ‘n’ Dry

This is an arid ecoregion, even though it gets its name from two rivers, the Columbia and the Snake. The area is dry because it's in the rain shadow of the Cascade Range. The moist ocean air coming eastward from the Pacific Ocean has to rise to get over the mountains. As it rises, it cools, dropping the rain west of or on the Cascade Mountains. By the time the winds reach the Snake/Columbia Shrub Steppe, they are dry.

Special Features

Natural fires here encourage the growth of grasses, since they can recover much more quickly than shrubs or trees. But the dominant vegetation is sagebrush, which has an advantage over grasses: Unlike grass, sagebrush grows well in times of drought.

	Many animals, such as bears, depended on salmon runs for food. Salmon once thrived in the rivers of this ecoregion, but are now largely gone. After a life in the ocean, they return to their original hatching sites in local streams and rivers to spawn. Dams and other human impacts on rivers hinder or even prevent the salmon from migrating homeward.

Wild Side

Besides sagebrush, other plants typical of the area are wheatgrasses, Idaho fescue, and other year-round bunchgrasses. In mountain ranges, you'll find juniper woodlands or even Douglas fir, subalpine fir, and aspen trees. Along rivers, cottonwoods and willows thrive. Wetlands within the ecoregion are important stopovers for both migrating and resident waterfowl. The Owyhee River once supported salmon and was considered one of the few high-desert spawning areas.

Cause for Concern

Domestic livestock overgrazes the grasses that native animals rely on and also compacts the soil, making it even more difficult for plants to grow back. Another threat to the ecoregion is the invasion of exotic grasses and noxious weeds. Farming has broken up the ecoregion into habitat fragments. Riparian habitats are especially damaged by excessive grazing by cattle. The recreational use of off-road vehicles also poses a looming threat.

For more information on this ecoregion, go to the World Wildlife Fund Scientific Report.