Global Warming and Sagebrush Steppe Habitat
Sagebrush steppe habitats cover 165 million acres in eleven western states (and one Canadian province). This widespread yet fragile ecosystem is characterized by abundant sagebrush, but also contains a diversity of other native shrubs, grasses and flowering plants. Sagebrush steppe terrain is typically flat or gently rolling, with water running intermittently through shallow creeks and occasionally deeper canyons. With low rainfall, vegetation is low and sometimes sparse, with the few trees largely confined to stream channels where water is more abundant.
Benefits for Humans and Wildlife
The headwaters of several great river systems--the Columbia, Colorado, and Missouri--originate in sagebrush steppe and provide important ecological services such as retaining nutrients and sediments, and capturing scarce snow and rainfall which flow downstream to provide critical water needs for agriculture and cities.
Sagebrush steppe is important to the ranching industry, as nearly all sagebrush habitats are grazed by livestock, whether on private or public lands. Sagebrush steppe habitats are essential for survival of sage-grouse and pronghorn, both uniquely adapted to consume sagebrush, and important for mule deer and elk, all of which are much sought after by sportsmen. More than 170 other species of birds and mammals utilize these semi-arid and cold habitats, including black-tailed jackrabbits, prairie falcons and golden eagles.
Threats from Global Warming
Nearly 60 percent of all sagebrush habitats could be lost if global warming pollution continues on a path of "business as usual," with carbon dioxide concentrations reaching double historic levels. The combination of global warming with other human-associated impacts, such as overgrazing, make these areas especially vulnerable. More severe droughts, together with high levels of livestock grazing would cause significant loss of soil as well as significant declines of perennial grasses and forbs important to many wildlife species and livestock.
The increase of severe droughts associated with global warming will exacerbate cheat grass growth and the spread of other harmful invasive species, thereby converting sagebrush steppe into exotic annual grassland with less forage value. Furthermore, cheat grass and other invasive plants increase the frequency and intensity of wildfires, thereby leaving sagebrush habitat with little chance of recovering, increasing the costs of fire suppression and control and increasing risks to human lives and facilities.
Conservation Investments to Minimize Global Warming Impacts
Maintenance of grazing land productivity for both wildlife and livestock as the climate warms will necessitate range-wide programs to limit the spread of cheat grass and other harmful invasive species, and to restore already degraded areas so that they have greater resilience to global warming. Erosion control measures will likely become necessary to reduce stream erosion and sedimentation to protect downstream water quality for ranchers, farmers and cities. As soil moisture declines and even mild droughts exacerbate water loss, efforts may be needed to supply surface water where natural sources have dried up.
The Western Association of Fish and Wildlife Agencies has called for new conservation measures to increase the resiliency of the sagebrush steppe habitats and sage-grouse populations they support. Protecting just sage-grouse habitats and populations, which now must endure the additional stresses of global warming, will require an estimated $431 million in spending by 2014.
Management activities include wildfire suppression, regeneration of sagebrush habitats and control of exotic invasive plants species. Managers will also need to monitor sagebrush steppe habitats for unexpected impacts of global warming and develop and implement programs to minimize these impacts as the needs arise.
How is climate change affecting Sagebrush Steppe and Grassland habitat? NWF teamed with Washington State Department of Fish & Wildlife to assess the impacts of climate change to these important areas. Compiling research from the scientific literature, we found that higher temperatures, drier summers, and other impacts are combining with land use changes such as agriculture and development to impair arid ecosystems, particularly by encouraging increased fire and invasive species.
Read the entire report: Climate Change Effects on Shrub-Steppe and Grassland Habitats in Washington State.