Elk - Exclosures
NPS Photo by Marie Curtin
All year long, quaking aspen contributes to the beauty of the Black Hills of South Dakota. During spring and summer, the soft green leaves of aspen flutter with every gentle breeze. In autumn, yellow-gold foliage provides stunning contrast to the deep, dark green of the ponderosa pine forest.
Throughout the coldest months, aspen's varying shades of white and gray-green bark provide subtle, yet beautiful contrasts in winter's muted palette of ice and snow. Aspen is an important species in the Western United States. Stands of aspen provide habitat for a variety of species, including birds, small mammals, deer and elk. In the West, aspen stands are considered to be second only to riparian areas, in diversity of vegetation and wildlife.
How does aspen grow?
When you look at a group of aspen trees, realize you are probably looking at a single tree or organism with many trunks interconnected by an extensive root system. Aspen trees produce seeds, but the seeds do not germinate readily. To regenerate, new trees sucker from the roots. An aspen stand with trunks interconnected by their roots is called a clone. The individual trees within a clone are not long-lived. Some begin to decline by about age 60. Few live to be more than 150 years old. But an aspen clone can be many thousands of years old, because it continues to regenerate itself by way of new suckers.
Threats to aspen
Stability and expansion of aspen stands can be thwarted by vegetation and by wildlife. Aspen clones are not shade tolerant. They do not compete well with ponderosa pines for sunlight and moisture. Wildlife can also pose a threat to aspen because aspen are a preferred food of elk. Elk browse aspen year-round, eating twigs, leaves, buds, suckers and bark. Some aspen stands are subjected to heavy use and become hedged at heights of less than three feet. Repeat browsing can stress clones and result in reduced sucker production.
Rocky Mountain Elk Foundation
How are we saving aspen at Wind Cave National Park?
Wind Cave National Park, the Rocky Mountain Elk Foundation, and the National Park Service Cooperative Conservation Initiative are working together to protect the park’s aspen. Pines have been removed from aspen stands, to reduce competition for sunlight and moisture. Wildlife fences have been installed at various locations. Fences reduce the availability of aspen to elk in the short-term. However, protection and expansion of aspen will, in the long-term, increase habitat and bio-diversity for many species of plants and wildlife, including elk.