The Condition and Trend of Aspen, Willows, and Associated Species on the Northern Yellowstone Range

Abstract

Aspen, willows, cottonwoods and other deciduous shrubs and trees play a pivotal role in the natural ecosystem function of the Northern Range, and they provide critical habitat for numerous species of native plants and animals. Deciduous shrubs and trees were much more abundant on the Northern Range in primeval times than they are today, especially on the portion of the Northern Range inside Yellowstone National Park. The primary cause of the declines in deciduous shrubs and trees is repeated heavy browsing by elk and bison–not normal plant succession or climatic changes - and heavy browsing is continuing to further degrade most Northern Range aspen, willow, and cottonwood plant communities inside Yellowstone National Park. Excessive browsing is occurring because modern-day management has allowed bison and elk populations to become unnaturally large. Current policy directs the National Park Service to intervene with active management where primeval and present conditions differ because of human actions.