Home > Ecosystems > Shrub-Steppe
Threats to the Shrub-Steppe
 Shrub-Steppe. Photograph by Andy & Ellen Stepniewski. Copyright 2008. All rights reserved. |
The primary ecological threats to sagebrush are: habitat conversion; soil disturbance due to heavy overgrazing, motorized recreation or other intensive land-use activities; invasive species; and altered fire regimes. Over 60% of original shrub-steppe habitats have been converted.
Unconverted areas are threatened by a negative feedback loop that combines disturbance, invasion of noxious weeds and more frequent fires. When fragile soils are disturbed and cryptobiotic soil crusts are removed, annual invasive species such as cheatgrass become established. Activities such as heavy overgrazing also can result in removal of palatable native bunchgrasses. Increased abundance of cheatgrass creates a continuous layer of flammable fuel in a system where vegetation is naturally patchy and sparse, separated by areas of cryptobiotic crust. Fire ignitions occur more frequently due to human activities and are then carried more easily due to cheatgrass invasion. Frequent fires remove sagebrush and increase the abundance of cheatgrass. Sagebrush is unable to successfully recolonize when fires occur in rapid succession. In areas where bunchgrasses have been removed due to grazing, little remains following frequent fires except cheatgrass and annual species.
 Badger Mountain with West Richland in the background. Photograph by Mickey Hunacek. Copyright 2008. All rights reserved. |
Primary goals for shrub-steppe conservation include: prevention of habitat loss through conversion; reduction of disturbance activities in unconverted habitat; and restoration of key habitat areas to dominant native species. Shrub-steppe conservation is currently a WNPS priority.
More on Percentages and Statistics
The shrub-steppe is an endangered ecosystem. It is estimated that about 12% of a functional shrub-steppe ecosystem remains in Washington and less than 1% is protected in ecological condition similar to the original vegetation. (From Shrub-steppe and Steppe Ecosystems of Washington, Rex Crawford, 1993).
A report prepared by The Nature Conservancy states that at least 80% of the shrub-steppe has been reduced (1996) and much of what remains has been substantially altered. It is an endangered ecosystem because it is estimated that less than 15% remains. (Henjum et al., 1994).
40% of the 10.4 million acres of the Columbia Basin shrub-steppe or approximately 4,160,000 acres are left. Dobler, F.C.J. Eby, C. Perry, S. Richardson, and M. Vander Haegen. 1996. Status of Washington shrub-steppe ecosystem: extent, ownership, and wildlife/vegetation relationships. Washington Department of Fish and Wildlife. Olympia. USA