Big Sagebrush Zone
The most widespread vegetation zone in the Pacific Northwest extends from Canada to Nevada and from the Cascades to the Rockies. Dominated by big sagebrush, the zone intermingles with juniper woodland in central Oregon and supports nonintensive grazing. Plant communities have been identified based on understory grasses, shrub cover, soils, and slope. Two prominent communities are Artemisia tridentata/ Festuca idahoensis and Artemisia tridentata/Agropyron spicatum associations, the former with greater moisture requirements. Low sagebrush (Artemisia arbuscula) frequently replaces big sagebrush in eastern Oregon on shallow stony soils. Other prominent shrubs include several species of sagebrush and rabbit brush (Chrysothamnus spp.). Commonly referred to as "high desert," the shrub-steppe in this zone consists of nondesert species and exhibits a shrub-grass structure which is distinct from true desert.