Nature & Science

Yellowstone National Park is as wondrous as it is complex. Established primarily to protect geothermal areas that contain about half the world's active geysers, the park also forms the core of the Greater Yellowstone Ecosystem. At 28,000 square miles, it is one of the largest, nearly intact temperate-zone ecosystems on Earth. It preserves a great variety of terrestrial, aquatic, and microbial life.

Natural processes operate in an ecological context that has been less subject to human alteration than most others throughout the nation—and throughout the world. This makes the park an invaluable natural reserve and reservoir of information.

A trail leads to a boulder on top of a hill with snow-capped mountains


A volcano, geysers and other thermal features, earthquakes, and glaciers shape Yellowstone's landscape.

Four pronghorn near a herd of bison in a wide, open valley


Abundant and diverse: 67 species of mammals, 330 species of birds, 16 species of fish, 5 species of amphibians, 6 species of reptiles.

Trees with yellow leaves and shorter vegetation along an open slope surrounded by mountains

Greater Yellowstone Ecosystem

Yellowstone is the core of one of the largest, nearly intact temperate-zones on Earth.

A close-up of red petals reach up


Plants are typical of the Rocky Mountains, with elements of the Great Plains, and unique plants in thermal areas.

A pika with leafy matter hanging out of mouth

Climate Change

Yellowstone's climate is changing. A continued rise in temperature will fundamentally alter the ecosystem.

Red smoke rises from a fire burning a hill of pine trees


Fire is a natural process and shapes the ecosystem.

A dark blue hot spring with a white crested edge rimmed by orange water

Thermophiles: Life in Extreme Heat

Thermal features are habitats for microscopic organisms called thermophiles: "thermo" for heat, "phile" for lover.

A park ranger holds a large fish next to two other employees

Science & Research

Scientists conduct research in Yellowstone that has the potential to change lives.


More Information

Other Organizations

Last updated: June 22, 2016

Contact the Park

Mailing Address:

P.O. Box 168
Yellowstone National Park, WY 82190-0168


(307) 344-7381

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