Ecological Health of Grasslands and Sagebrush Steppe on the Northern Yellowstone Range

Abstract

On the Ground • Native plant abundances within the grasslands and sagebrush steppe of the Northern Range decreased substantially during the 20th century and the degradation has continued during the 21st century. • Forage production has declined precipitously, and ecological processes (i.e., water cycle, energy flow, and nutrient cycle) are impaired and degrading further. • The declining health of Northern Range grasslands and sagebrush steppe is primarily caused by heavy grazing and browsing by bison and elk, not climatic changes. • Excessive grazing and browsing is caused by modern-day management decisions that allowed bison and elk populations to become much larger than primeval times. • National Park Service policy requires human intervention (i.e., active management) when human actions have impaired natural ecological processes or altered natural abundances of native plants and animals.