In Idaho and several other western states the iconic stands of aspen trees are disappearing. They also happen to be the most widespread tree in North America, you can still see the unmistakable groves, especially in the fall, only now some conifer species are moving in. Normally this wouldn’t be cause for alarm, it would be biodiversity but in the case of the aspen it may be a death sentence. The decline is especially noticeable in western states, eastern Idaho’s aspen population once made up 40% of species in the region’s forested areas, but has experienced a 60% loss over the past century. Arizona has seen a 90% loss in their aspen community.
Federal departments and state agencies see this as a very important issue, aspen trees are a keystone species. A keystone species is “A species whose presence and role within an ecosystem has a disproportionate effect on other organisms within the system. A keystone species is often a dominant predator whose removal allows a prey population to explode and often decreases overall diversity. Other kinds of keystone species are those, such as coral or beavers, that significantly alter the habitat around them and thus affect large numbers of other organisms.” In the case of the aspens, they help maintain biodiversity while keeping other species in check which may otherwise come to dominate the ecosystem, they also provide integral resources to a wide range of species. And, according the Idaho Department of Fish and Game, eastern Idaho is losing 5,000 acres of aspen each year.
In Idaho an inter-agency team has been formed to address the problem, members include staff from Fish and Game, the U.S. Forest Service, Bureau of Land Management, Idaho Department of Lands, Idaho Department of Parks and Recreation and Idaho State Department of Agriculture. Their committee is entitled “The Eastern Idaho Aspen Working Group”, and since 2006 their mission has been to preserve the disappearing species.
Conservation of aspen trees is vital to the wildlife population, deer and elk are especially dependent on the trees. Research regarding fawns and calves of these animals found that individuals reared within dense aspen groves are healthier than those found in other forest types. Aspen have a higher fat content than many other species, so shoots are a valuable commodity in winter months. Aspen trees are generally pioneer species, as such they have a relatively short life span of only 70 to 100 years. They are vital to the nutrient cycle as they will die, decompose and return nutrients to the soil faster than many other species. Additionally, aspen trees have somewhat sparse canopy cover, this allows precipitation to fall to the floor and infiltrate into the groundwater recharging aquifers rather than evaporating on leave surfaces.
The Working Group has found that aspen decline is mainly due to fire suppression and juniper encroachment. Aspen trees have deep root systems which can survive fire and proceed to root sprout and repopulate, while competitor species will be destroyed, without fires aspen do not receive this benefit. Juniper have a broad, far-reaching root system which greedily sucks moisture out of the soil and can choke out aspen communities. The inter-agency committee has been removing juniper and other encroaching conifers and attempting controlled burns in an effort to protect the species and help it thrive once more. People do not like to see smoke and fire in their community though, so it is a hard sell. Although their attempts are noble and worthwhile, they are hobbled by not being able to utilize all of the tools available and as such are not keeping pace with the dramatic annual loss.
