Hells Canyon, eastern Oregon, USA Photograph by Daren H Spencer   Temperate Grasslands, Savannas, and Shrublands   18,100 square miles (46,900 square kilometers) -- about the size of Vermont and New Hampshire combined Critical/Endangered

· Biological Distinctiveness
· Conservation Status
· Conservation Activities
· Relationships
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Introduction

Grasslands and savannas once covered large areas of the intermountain west, from southwest Canada into western Montana (Sims 1988). Today, areas like the great Palouse prairie of eastern Washington, northeastern Oregon, and northwestern Idaho are virtually gone. The Palouse, formerly a vast expanse of native bluebunch wheatgrass (Agropyron spicatoin), Idaho fescue (Festuca idahoensi), and other grasses, has been plowed and converted to wheat fields or is covered by cheatgrass (Bromus tecturum) and other exotic plant species (Noss and Peters 1995).

The Palouse lies in the rain shadow of the Cascades and has a generally semiarid climate. This climate is similar to that of the annual grasslands of California, yet the Palouse historically resembled the mixed-grass vegetation of the central grasslands, except for the absence of short grasses. Such species as Agropyron spicatum, Festuca idahoensis, and Elymus condensatus, and the associated species Poa scabrella, Koeleria cristata, Elymus sitanion, Stipa comata, and Agropyron smithii originally dominated the Palouse prairie grassland (Sims 1988).

Fire was a major force in shaping the Palouse. For thousands of years, Native Americans set periodic, cool-burning fires that did not damage perennial grasses. Without frequent burning to reduce fuel levels, conditions were ideal for rare but intense fires that destroyed the native perennial species and allowed exotic grasses and annual forbs to invade. Excessive grazing also resulted in the demise of many of the perennial grasses (Sims 1988).

The Palouse prairie is now intensive agricultural land with patches of shrub-steppe grassland. Once a rich ecosystem year-round, the species that invaded the Palouse following the increase in grazing and the change in fire regime transformed these grasslands to seasonal rangelands.

Biological Distinctiveness

Except for the presence of shrubs, the Palouse grassland resembles the Great Plains shortgrass prairie. The once-dominant species, however–bluebunch wheatgrass, Idaho fescue, and bluegrass–are distinctive.

Conservation Status

Conversion to agriculture has destroyed more than 99 percent of the Palouse grasslands.

Only two relatively large blocks of more or less intact habitat remain:

• Hell’s Canyon National Recreation Area - eastern Washington - 795 km²
• Coulee Dam National Recreation Area - eastern Washington - 279 km²

The Palouse Grasslands are highly fragmented. Remaining patches are tiny, with effectively no connectivity in most areas and little core habitat due to edge effects. The individual fragments and clusters that remain are highly isolated, and the intervening landscape precludes dispersal for most taxa.

Two protected areas in this ecoregion exceed 500 km² (see above).

The Palouse does not face serious threats from agriculture because nearly all of the habitat has already been converted. Degradation of the remaining fragments continues to be a problem, and there are still moderate levels of wildlife exploitation.

Suite of Priority Activities to Enhance Biodiversity Conservation

Given that nearly all of this ecoregion has already been destroyed, conservation activities are largely futile. Acquisition and preservation of the remaining fragments should nevertheless be a priority, as should restoration of any abandoned agricultural land.

Conservation Partners

• Idaho Conservation Data Center
• The Nature Conservancy Of Washington
• The Nature Conservancy - Western Region
• The Nature Conservancy of Idaho
• The Nature Conservancy of Oregon
• Oregon Natural Heritage Program
• Washington Natural Heritage Program

For more general information on this ecoregion, go to the WildWorld version of this description.