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.


Greater Yellowstone Ecosystem
The Greater Yellowstone Ecosystem consists of 12-22 million acres and 18,750-28,000 square miles. It is located in Wyoming, Montana and Idaho and encompasses state lands, two national parks, portions of five national forests, three national wildlife refuges, Bureau of Land management holdings and private and tribal lands.


Climate Change
Yellowstone's climate is changing. Climate is one of the primary drivers of the processes that make an ecosystem look and function the way it does.


Yellowstone was established as the world's first national park primarily because of its extraordinary geology. Its mountains and canyons may appear to change little during our lifetime, but they are highly dynamic.


Yellowstone's abundant and diverse wildlife are as famous as its geysers.

67 species of Mammals
330 species of Birds
16 species of Fish
5 species of Amphibians
6 species of Reptiles

The vegetation communities of Yellowstone include combinations of species typical of the Rocky Mountains, the Great Plains, and the region to the west.

Hydrothermal Plant Communities | Rare Plants | Trees and Shrubs | Invasive Plants | Yellowstone Herbarium


Fire is key in shaping the ecology of the Greater Yellowstone Ecosystem. For the first 100 years, managers extinguished fires to preserve park resources. The 1988 fires marked a change in how the public thought about fire in ecosystems. Today, the National Park Service aims to restore fire's role as a natural process as feasible.


Other Life Forms: Life in Extreme Heat
The hydrothermal features of Yellowstone are evidence of Earth's volcanic activity. They are also habitats for microscopic organisms called thermophiles—"thermo" for heat, "phile" for lover.


Science & Research
Scientists conduct research ranging from large studies of landscape-level changes affecting the local ecosystem to studies of tiny organisms that have the potential to change lives beyond the park boundaries.


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