Palouse Prairie Description 

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Palouse Prairie

Geomorphology. The Palouse prairie comprises moderately to strongly dissected loess-covered basalt plains, hills with large steptoes, undulating plateaus, and some river breaklands. Mountains occur in the southeast part of the Section. The Palouse prairie is within the Columbia Plateau physiographic province. Elevation ranges from 1,200 to 6,000 ft (366 to 1,830 m).

Lithology and Stratigraphy. There is Tertiary basalt with some Paleozoic granitic and metasedimentary outcrops in breaklands. Granitoid rocks of the Blue Mountain uplift are evident, as well as sedimentary rocks which occur at the boundaries of the flood basalt deposits.

Soil Taxa. Soils include mesic Xerolls with some Xeralfs, Albolls, and Aquolls. These soils are generally deep, loamy to silty, and have formed in loess, alluvium, or glacial outwash. Soils in mountainous areas are shallower and contain rock fragments.

Potential Natural Vegetation. Grasslands and meadow-steppe vegetation dominated by grasses are the prototypical vegetation of the Palouse. Woodlands and forests occur in the eastern portion of the Section on hills and low mountains. The relatively arid western portion of the Section is dominated by grassland, where bluebunch wheatgrass and Idaho fescue are the most prominent. Meadow-steppe vegetation characterized by Idaho fescue and common snowberry dominates areas with more precipitation, but still too dry to support forest vegetation on deep loamy soils. Most of this meadow-steppe as well as the grassland to the west, has been converted to crop lands. Ponderosa pine woodlands and forests form the lower timberline in the eastern portion of the Section on hills and low mountains. The transition zone between forest and meadow-steppe consists of a complex interfingering between these two vegetation types. Douglas-fir series forests dominate at higher elevations in the mountains. Isolated fragments of the Western Red Cedar series and Grand Fir series occur on sheltered north slopes in the mountains.

Fauna. Birds are typical of grasslands with intermittent riparian systems and pine hills. Grassland species include American kestrel, ring-necked pheasant, upland sandpiper, western kingbird, horned lark, black-billed magpie, western meadowlark, and savanna sparrow. Riparian system species include Lewis' woodpecker, gray catbird, western bluebird, orange-crowned warbler, northern oriole, black-headed grosbeak, and lazuli bunting. Birds which reach or nearly reach the extent of their range include mountain quail, barn owl, white-headed woodpecker, eastern kingbird, and American redstart. The bald eagle, an endangered species, also occurs around larger water bodies. Typical herbivores and carnivores include white-tail deer, mule deer, and bobcat. Smaller common herbivores include the blacktail jackrabbit and Washingtion ground squirrel. Rare species include the whitetail jackrabbit, and possibly the pygmy rabbit. Herpetofauna typical of this Section are the bullfrog, painted turtle, western fence lizard, and the northern Pacific rattlesnake.

Climate. Precipitation ranges from 10 to 30 in (250 to 760 mm), evenly distributed throughout fall, winter, and spring. Winter precipitation is mostly snow; summers are relatively dry. Climate is warm temperate with a maritime influence. Temperature averages 45 to 54oF (7 to 12oC). The growing season lasts 100 to 170 days.

Look at Moscow, Idaho's climate statistics from the U.S. Forest Service Rocky Mountain Research Station's Rock:Clime climate program.

Surface Water Characteristics. There are scattered coulees and deeply-incised major drainages. Loess plains have low to medium density dendritic drainage patterns. Rapid changes in runoff volumes are possible on basalt due to gain or loss of water to gravel interbeds. The Snake River flows through the Palouse prairie.

Disturbance Regimes. Wind is the principal source of natural disturbance.

Land Use. Dry farming and livestock grazing occurs on about 90 percent of the area.

Modified ever so slightly from:

McNab, W. Henry and Avers, Peter E., compilers. 1994. Ecological Subregions of the United States. USDA Forest Service, Washington Office, publication WO-WSA-5. "Prepared in cooperation with Regional Compilers and the ECOMAP Team of the Forest Service, July 1994." Published online 10/30/1996 at [08/13/2001]

Chapter 41: Great Plains--Palouse Dry Steppe [province 331]; Section 331A--Palouse Prairie (1 of 10 sections of province 331). Online at [08/13/2001] Compiled by USDA Forest Service Northern Region.