Plant Responses to Spring Grazing by Elk in Yellowstone National Park

Management of elk on the northern winter range of Yellowstone National Park has remained a controversial subject through most of this century (Singer 1989). Until 1968 elk were artificially controlled because it was believed that ranching outside the park excluded elk from winter ranges resulting in unnaturally high populations in the Park and uncontrolled elk numbers would result in overgrazing and ecosystem degradation. However, in 1968 elk reductions were terminated and by 1971 a hypothesis of natural regulation was formulated by Park biologists (Singer 1989). The natural regulation hypothesis asserts that the Yellowstone area used by elk is an ecologically complete habitat (all required components of the habitat are present) and that density dependant factors will limit population growth of elk without major range degradation.