Changing Seasons: Aspen Conservation in the Interior West

photo by Fields Ford

photo by Fields Ford

Dispatch by Fields Ford

In the interior American West, aspen trees are a common feature of high elevation landscapes, signifying a wealth of biodiversity and often an accompanying, healthy ecosystem. Aspen stands, each of which is a single, underground organism shooting up numerous sprouts, are well-known and loved for both their vivid fall color and they valuable habitat they provide. Behind riparian areas, aspen stands provide the second most biodiverse habitat in the West. Aspen trees provide shade for forbs, grasses, and shrubs growing in the understory, as well as housing for cavity nesting species. The trees, which are also edible for some animal species, often grow in areas with more moisture, participating in the greater biodiversity associated with the presence of water. The iconic aspen stands, however, are often located on public lands. This means that the organisms are susceptible to the damages associated with cattle that graze on public allotments, meaning Forest Service or BLM tracts of land upon which ranchers are allowed to run their cattle. Aside from this, aspen growth and regrowth is also limited by the browsing of wild ungulates, including elk and mule deer, as well as a lack of fire, or general disturbance. Because fire suppression has been at the forefront of forest management in the United States, aspen—which depend on disturbance for survival—are often shaded out by conifers that would otherwise be burned down. Anthropogenic climate change, too, heavily impacts aspen health. One effect of a warming climate is increased drought frequency and intensity, both of which reduce the likelihood of aspen survival. Associated with drought is Sudden Aspen Decline, a phenomenon caused by insufficient precipitation or moisture content resulting in the abrupt death of huge swaths of aspen stands. 

Although aspen stands are threatened by these varied factors, people are working to conserve aspen stands in the West. In the Fishlake National Forest, conservationists are working to restore aspen in such areas. In June 2014, a prescribed fire burned off conifers competing with aspen for sunlight, moisture, and soil nutrients. The fire, which burned in the Twin Peaks area of Monroe Mountain, theoretically provided the disturbance needed to catalyze aspen regrowth. The goal of regrowth is to produce aspen recruits; that is, trees that reach six feet in height, a measure that is too tall for the buds to be browsed, or stripped off, by ungulates. Because the fire was so recent, though, the Twin Peaks aspen are still vulnerable to being browsed by both cattle and exotic elk, which were introduced for hunting in 1985. The project has been met with mixed success, as large patches of sprouts are nearing recruitment, but some areas are still being browsed.  Though efforts to conserve aspen are being made, it is imperative that stands, especially those on public lands and consequently vulnerable to browsing, be allowed to regrow so that biodiverse habitats may continue to thrive in the face of biodiversity-reducing anthropogenic climate change.