The authors of this study linked the overall decline of willows (Salix spp.) in Yellowstone and Rocky Mountain National Parks to the increasing elk (Cervus elaphus) populations in these parks since predators were reduced and natural regulation policies were instated. In general, Rocky Mountain National Park was a better growth environment for willows; willow height and annual growth were not affected by clipping and willows increased secondary compounds in response to defoliation. In contrast, in Yellowstone National Park, clipping reduced height and annual growth of willows and did not increase secondary compound concentrations. Other factors, such as reduced beaver populations, human disturbances on winter range, the long-term increase in average temperatures and decrease in precipitation levels also affect willow populations in these areas. However, these impacts appear to be secondary, in relation to the impacts caused by overabundant elk populations.
Citations and enhanced abstracts for journals articles and documents focused on rangeland ecology and management. RSIS is a collaboration between Montana State University, University of Idaho, and University of Wyoming.