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Wind Energy Development Map: Sage Steppe Communities Oregon/Washington BLM



Wind Energy Development Map: Sage Steppe Communities


Oregon sagebrush communities are part of 3 floristic provinces: Columbia Basin in north central Oregon, Northern Great Basin in south central Oregon, and Snake River Plain in far eastern Oregon. Main different types of sage seen in Oregon are Wyoming big sage, and basin big sage in the north; Wyoming, mountain and low sage in the middle & south parts of eastern OR, and finally Wyoming and basin big sage with some mountain big sage in the eastern part of OR (1).

Forbs are a smaller part of the community, but contain nutrients that are essential for egg production and brood rearing of sage grouse. Artemisia arbuscula, low sagebrush, is another important community member that is found in shallower, rocky soils in Oregon. Sage brush provides many important functions, including:

  • Winter range forage for wildlife; it is high in protein
  • Cover for wildlife
  • Sage-grouse feed and cover
  • Significant diffuse root system which continually adds to the soil organic material 1/3 of the roots die each year
    • Can more than double the thickness of the soil profile in part because the plants grow throughout the season while many grasses and forbs stop. Create litter and hummus that is important to nutritional cycling as well as soil hydrology processes
    • Protection for grasses against trampling and grazing, allowing grasses to grow around the base of shrubs
    • Big and low sagebrush less than 50 years old are killed by fire (2)

Sagebrush Biome

The following information is courtesy of Richard F. Miller and Lee. L Eddleman, see citation (3).

Sagebrush Biome Map
  • The Columbia Basin (area 1, Fig. 2) contains the lowest elevation sagebrush communities in the sagebrush biome. Predominant sagebrush in this region are Wyoming big sagebrush (Artemisia tridentata var. wyomingensis) and basin big sagebrush (A. tridentata var. tridentata). The Columbia Basin sagebrush steppe is bordered by the Palouse Prairie and coniferous forests. Precipitation primarily occurs in the winter and spring. The basin is underlain by vast lava flows however, soils have been greatly influenced by glacial loess and Pleistocene outwash (Rickard and Vaughn 1988). Soils commonly range from sandy loams to silt loams.
  • The northern Great Basin sagebrush steppe (area 2, Fig. 2) occurs between salt deserts occupying valley floors and woodlands, conifer forests, and alpine meadows. Predominant sagebrush are Wyoming big sagebrush, mountain big sagebrush (Artemisia tridentata var. vaseyana), and low sagebrush (A. arbuscula). Precipitation primarily occurs in the winter and spring. Soils are typically derived from volcanic materials (West 1983), with some outcropping of sedimentary materials (Walker and MacLeod 1991).
  • Sagebrush communities in the Snake River Plain (area 3, Fig. 2) lie between the salt deserts occupying the low valleys and the coniferous forests at the upper elevation. The sagebrush component is dominated by Wyoming big sagebrush and basin sagebrush. Mountain big sagebrush primarily occurs at the higher elevations in the mountains. Summer precipitation events increase from west to east. The Snake River Plain is built on numerous lava flows overlapped by alluvial fans from the massive granite Idaho batholiths to the north and the largely sedimentary mountains to the east and south (Hironaka 1979, West 1983) (Miller and Ettleman, 6).

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