Chapter 2 An introduction to Yellowstone and the Greater Yellowstone Ecosystem
Chapter 2 An introduction to Yellowstone and the Greater Yellowstone Ecosystem
2.3 Introduction to the Greater Yellowstone Ecosystem
What is the Greater Yellowstone Ecosystem
What defines an ecosystem? It is a system that includes all living organisms (biotic factors) in a geographic area, as well as the physical environment (abiotic factors), functioning together and interacting as a unit.
At 3,437.5 square miles (8,903 km2),Yellowstone National Park forms the core of the Greater Yellowstone Ecosystem (GYE)—one of the largest nearly intact temperate-zone ecosystems on Earth (Figure 2.3.2). 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.
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. Today, the GYE is home to one of the largest elk herds in North America, the largest wild and free-roaming herd of bison in the U.S., one of the free grizzly populations in the contiguous U.S., and at the forefront of the reintroduction of wolves to the Northern Rockies of the U.S. 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.
The exact boundaries of the Greater Yellowstone Ecosystem are difficult to define given that the size, boundaries, and description of any ecosystem may vary, and there are no fences that can keep plants, animals, climatic effects, and Earth processes in or out of any given area (Figure 2.3.2 left). Though Yellowstone National Park comprises the core of the GYE, the GYE also includes state lands that encompass parts of Montana, Wyoming, and Idaho, two national parks (Yellowstone and Teton National Park), portions of five national forests, three national wildlife refuges, Bureau of Land Management holdings, private lands, and tribal lands (Figure 2.3.2 right). As such, land within the ecosystem is managed by many different entities: state governments, different agencies within the federal government, tribal governments