White et al. comparatively studied the research literature and historic photographs to evaluate aspen (Populus tremuloides) change over time in 6 Rocky Mountain national parks in Canada and the United States: Jasper, Banff, Yoho, Kootenay, Yellowstone, and Rocky Mountain. Across all parks, aspen has consistent responses to increased browsing by ungulates and decreased frequency of fire. Trees are intermediate to mature in age, and elk (Cervus elaphus) browse off the new suckers before they reach 2 m in height. Fire, combined with browsing, has hindered regeneration of aspen. The exception to this pattern is northern Jasper National Park, where elk densities appear to have been reduced by wolves in the 1970s, and aspen regenerated. The authors recommendations to national park managers are to restore carnivores, use fire in areas of low elk density, and control human uses that displace carnivores.
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.