Since the reintroduction of the grey wolf the vegitation of Yellowstone has flourished. Its eco-region is predominantly coniferous forest, dominated by lodgepole pine. Other trees include Engelmann spruce, Rocky Mountain fir, subalpine fir and trembling aspen. Whitebark pine is an important species at the upper tree line krummholz zone. This eco-region also contains mountain meadows, foothills grasslands, riparian woodlands, and alpine tundra. In some areas, geothermal activity creates distinct, warm habitats with unique floral communities.
The Greater Yellowstone Ecosystem is one of the last remaining large, nearly intact ecosystems in the northern temperate zone of the Earth. It is located within the northern Rocky Mountains, in areas of northwestern Wyoming, southwestern Montana, and eastern Idaho. Yellowstone National Park and the Yellowstone Caldera ‘hotspot’ are within it. The Greater Yellowstone Ecosystem 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.