Greater Yellowstone Ecosystem

A lone proghorn lies on a hillside in front of a snow-capped peak.
The Greater Yellowstone Ecosystem, with Yellowstone at its core, is one of the largest nearly intact temperate zone ecosystems on Earth.

NPS / Jacob Frank

Map of Idaho, Montana, and Wyoming with public lands of the Greater Yellowstone Ecosystem in green.
The Greater Yellowstone Ecosystem. Description of an ecosystem's size, boundaries, and characteristics can vary greatly.

At 3,437.5 square miles (8,903 km2),Yellowstone National Park forms the core of the Greater Yellowstone Ecosystem—one of the largest nearly intact temperate-zone ecosystems on Earth. Greater Yellowstone’s diversity of natural wealth includes the hydrothermal features, wildlife, vegetation, lakes, and geologic wonders like the Grand Canyon of the Yellowstone River.

Heart of an Ecosystem

Yellowstone National Park was established in 1872 primarily to protect geothermal areas that contain about half the world’s active geysers. At that time, the natural state of the park was largely taken for granted. As development throughout the West increased, the 2.2 million acres (8,903 km2) of habitat that now compose Yellowstone National Park became an important sanctuary for the largest concentration of wildlife in the lower 48 states.

The abundance and distribution of these animal species depend on their interactions with each other and on the quality of their habitats, which in turn is the result of thousands of years of volcanic activity, forest fires, changes in climate, and more recent natural and human influences. Most of the park is above 7,500 feet (2,286 m) in elevation and underlain by volcanic bedrock. The terrain is covered with snow for much of the year and supports forests dominated by lodgepole pine and interspersed with alpine meadows. Sagebrush steppe and grasslands on the park’s lower-elevation ranges provide essential winter forage for elk, bison, and bighorn sheep.

Water cascades over a cliff into a canyon
Influence of Geology

Geological characteristics form the foundation of an ecosystem.

A smoke plume from a wildfire billows up into the sky, reducing the air quality.
Air Quality

Yellowstone National Park is a Class I airshed. The largest source of particulate matter in Greater Yellowstone is smoke from wildland fire.

A bull elk bugles in front of a building

Sounds have an important ecological function for reproduction and survival. Together they form a soundscape.

Water flows over the Brink of Lower Falls in the Grand Canyon of the Yellwostone

Learn about the role of water in Yellowstone and beyond.

Grizzly bears and ravens feed on a carcass near a couple of ponds.
Cycles and Processes

Many animals migrate seasonally, following the new growth of grasses and other food sources.

Bison walk single-file on a path through snow
Winter Ecology

Winter in Yellowstone is a place of magic and vulnerability.

A presenter speaks in front of an audience of multiple agency representatives.
Beyond Boundaries

Managers from local, state, and federal agencies across the Greater Yellowstone Ecosystem coordinate efforts around resource issues.

An aerial view of the Gallatin Valley of Montana in the Greater Yellowstone Ecosystem.
Land Use

How land is used outside the park can disrupt ecological processes within the park.

A waterfall drops over a gray rock cliff and a rainbow glows in the spray.

More than 2 million acres of Yellowstone are recommended for federal wilderness designation and managed as such.

Snowmobilers drive cautiously by a herd of bison on a snow covered park road.
Winter Use

The winter use debate spans more than 80 years, with each participant asking: should the park be accessible in winter?

Photo of a bull elk bugling

Discover the natural wonder of Yellowstone and our role in the conservation of wildlife.

Last updated: August 21, 2020

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PO Box 168
Yellowstone National Park, WY 82190-0168



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