Greater Yellowstone Ecosystem

The Greater Yellowstone Ecosystem (GYE) is one of the last remaining large, nearly intact ecosystems in the northern temperate zone of Earth. It is located within the central Rocky Mountains, in areas of northwestern Wyoming, southwestern Montana, and eastern Idaho, and is about 22 million acres (89,000 km²). Yellowstone National Park and the Yellowstone Caldera 'hotspot' are within it.

The area is a flagship site among conservation groups that promote ecosystem management. It is one of the world's foremost natural laboratories in landscape ecology and Holocene geology, and is a world-renowned recreational destination. It is also home to the diverse native plants and animals of Yellowstone.

Yellowstone National Park boundaries were drawn in 1872 with the intent to include all the known geothermal basins in the region. As landscape ecology considerations were not incorporated into original boundary, revisions were suggested to conform more closely to natural topographic features, such as the ridgeline of the Absaroka Range along the east boundary. In 1929, President Hoover signed the first bill changing the park's boundaries: The northwest corner now included a significant area of petrified trees; the northeast corner was defined by the watershed of Pebble Creek; the eastern boundary included the headwaters of the Lamar River and part of the watershed of the Yellowstone River. In 1932, President Hoover issued an executive order that added more than 7,000 acres (2,800 ha) between the north boundary and the Yellowstone River, west of Gardiner. These lands provided winter range for elk and other ungulates. By the 1970s, the grizzly bear's (Ursus arctos) range in and near the park became the first informal minimum boundary of a theoretical "Greater Yellowstone Ecosystem" that included at least 4,000,000 acres (16,000 km²). Since then, definitions of the greater ecosystem's size have steadily grown larger. A 1994 study listed the size as 19,000,000 acres (76,890 km²), while a 1994 speech by a Greater Yellowstone Coalition leader enlarged that to 20,000,000 acres (80,000 km²).

In 1985 the United States House of Representatives Subcommittees on Public Lands and National Parks and Recreation held a joint subcommittee hearing on Greater Yellowstone, resulting in a 1986 report by the Congressional Research Service outlining shortcomings in inter-agency coordination and concluding that the area's essential values were at risk.

Federally managed areas within the GYE include:

Ten distinct National Wilderness Areas have been established within the GYE's National Forests since 1966, mandating a higher level of habitat protection than the USFS otherwise uses.

The GYE also encompasses some privately held and state lands surrounding those managed by the U.S. Government.

The Trust for Public Land has protected 67,000 acres (27,000 ha) over about 40 projects in the Greater Yellowstone Ecosystem.