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An ecosystem includes not only the biological components of a particular environment, like plant and animal species, but also abiotic (nonliving) processes, like nutrient and energy cycles. The health of all species living in the Yellowstone area depends on the proper functioning of these processes.

It is hard to define the boundaries of any ecosystem. An ecosystem can be as small as a forest patch, or as large as the entire planet. For management purposes, however, the National Park Service and the United States Forest Service have designated 18 million acres of land in Idaho, Montana, and Wyoming, as the “Greater Yellowstone Ecosystem” (GYE). These lands include not only the national park itself, but also surrounding areas that provide critical habitat for wildlife species, or support important ecological processes, such as portions of the region’s many river systems. For more information about the Greater Yellowstone Ecosystem, please refer to the Greater Yellowstone Coalition’s web site.

Nineteen percent of land in the GYE is privately owned. Some of these areas are already facing rapid exurban development, especially around Jackson, Wyoming and in the so-called “Paradise Valley” south of Livingston, Montana. Most of the private landholdings in the GYE are located in prime low-elevation habitat such as river valleys and the surrounding wetlands (Hansen and Rotella 2000). These areas have a more equitable climate and higher primary productivity than the surrounding uplands, and thus are preferred habitat for many wildlife species (Hansen and Rotella 2000).

“Ranchettes”

Over 1 million acres of rangeland in the GYE was subdivided into smaller “ranchette” parcels as of 1990 (Witkowsy and Lawlor 1995). These developments not only introduce humans and potentially predatory pets into areas previously disturbed only by grazing livestock, but they necessitate the construction of roads. Roads pose numerous threats to wildlife, including acting as “filters” which only some species are able or willing to cross, as invasion corridors for exotic species, and heighten the chances that an animal will be run down by a car or truck (Theobald et al 1996). Roads also cause polluted runoff to enter nearby rivers, lakes, and streams, degrading habitat even further.

Fire

Because private lands in the GYE are widely dispersed, there is a large interface between the public and private holdings, and thus a high potential for conflict between individual citizens and government agencies. One of the most volatile issues is how to manage natural disturbances like fires and floods. The GYE is an arid area, and fire was historically a very important ecological process here. Frequent fires maintained the region’s grasslands and lodgepole pine forests, and local animal species (like grazing bison) evolved to live in these habitats. Although fires were suppressed in the national park in the early part of this century, the recent policy of the National Park Service is to let fires burn naturally (Knight 1991). However, fires here are usually initiated in the dry, valley-bottom grasslands, where most of the exurban development has taken place, and thus are extinguished by residents or local fire departments before they have a chance to spread into the publicly owned upland areas (Hansen and Rotella 2000). This change in the fire regime has the potential to affect plant communities, and the animal species that live in them, on a large scale.

Flooding

In recent years, many conflicts have centered on controlling floods on the Yellowstone River. The “Paradise Valley” of the Upper Yellowstone River is one of the fastest growing regions of Montana, and people want to live along the beautiful riverbank. Unfortunately, they are not willing to face the consequences of living near a large and unpredictable river. At 670 miles, the Yellowstone is the longest undammed river in the lower 48 states, but it is far from free-flowing. In 1996 and 1997, “100 year” floods hit the Yellowstone two years in a row (Kesselheim 2000). During the following two years, the Army Corps of Engineers issued 82 permits for Yellowstone River flood control projects in Park County (Kesselheim 2000). Most of these projects called for the installation of “riprap” – stones or concrete blocks laid along the riverbank to prevent erosion (Kesselheim 2000). These projects went ahead despite warnings from the Fish and Wildlife Service that the riprap and levees could threaten trout habitat. In May, 1999, six Montana conservation groups sued the Army Corps of Engineers for failing to consider the cumulative impacts of river armoring on fish and wildlife habitat and hydrological processes (see www.greateryellowstone.org/yellowstone_river_news.html for more details). In May, 2000, a judge ruled against the Corps, but the effects of this ruling are uncertain. Many proponents of flood control are wealthy and politically powerful, like the owners of the famous fishing streams called “spring streams” which flow into the Yellowstone. These landowners are well represented on Governor Marc Racicot’s Upper Yellowstone River Task Force, and conservation groups worry that the group may oppose scientific monitoring of the area (Kesselheim 2000).

References:

Hansen, Andrew J. and Jay J. Rotella. 2000. Nature reserves and land use: implications of the

“place” principle. In Applying Ecological Principles to Land Management, edited by

Kesselheim, Alan S. 2000. The last wild river. Retrieved April 15, 2001 on the world wide

Knight, Dennis H. 1991. The Yellowstone fire controversy. In The Greater Yellowstone

ecosystem: redefining America’s wilderness heritage, edited by Robert B. Keiter and

Theobald, D. M., H. Gosnell, and W.E. Riebsame. 1996. Land use and landscape change in the

Colorado mountains II: a case study of the East River valley. Mountain Research and

Witkowsky, Kathy and James Lawlor. 1995. Montana under the gun. Planning 61: 4-10.

Ecosystem Aspects of Human Settlement

“Ranchettes”

Fire

Flooding

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