Little Whitehorse Exclosure Research Natural Area

Vale District , BLM

Northern Basin and Range Ecoregion

Cell(s):

• Riparian community dominated by mountain alder and creek dogwood or snowberry

Access by road going into Oregon Canyon Mountains south of Whitehorse Ranch Road, west of U.S. Highway 95; accessible late spring to fall when dry.

The 23 ha RNA is an exclosure in a narrow canyon of Little Whitehorse Creek, Malheur County, Oregon, northwest of McDermitt, Nevada. The topography is a small canyon rimmed by basalt cliffs. Soils are deep riparian alluviums, over basalt. Elevation in the RNA ranges from 1490 to 1555 m. Summers are hot and dry; winters, cold and moist. Annual precipitation averages 20 to 25 cm. The RNA was established to protect a high gradient reach of a first to third order stream in the sagebrush zone with the following riparian communities: mountain alder (Alnus incana) and creek dogwood (Cornus sericea) with potential for black cottonwood (Populus trichocarpa), and Pacific willow (Salix lucida) with Wood's rose (Rosa woodsii). Another important resource in Little Whitehorse Creek is Lahontan cutthroat trout, a Federally-listed threatened species. The exclosure was constructed in 1972 and represents 32 years of natural recovery for the riparian and aquatic systems following cessation of grazing and other impacts. However, in 2003, five cow/calf pairs were trapped for an unknown period of time during summer inside the exclosure and consumed all of the herbaceous vegetation and much of the woody vegetation.