This study on the Isle Royale National Park inferred how moose (Alces alces) and beaver (Castor canadensis) affect current and future landscape patterns. About 40% of the bites by moose in both winter and summer were aspen (Populus tremuloides) in this study area. In beaver-cut areas and in uncut forest, aspen was the only browse species that was preferred by moose in both summer and winter. Browsing on balsam fir (Abies balsamea) reproduction was not sufficient to prevent regeneration. Balsam fir was avoided in the upland forest, but it was neither avoided nor referred in the beaver-cut areas. Nearly all the aspen within the 27.7-m foraging distance have been cut around every active or abandoned pond in the study site. Beaver prefer to cut small trees first and most of the aspen trees remaining were greater than 35-cm dbh. Results from this study suggest that moose and beaver can change the rate and path of succession in this part of Isle Royale. Where moose alone are the major browsers, the canopy of deciduous trees provides an annual input of high quality deciduous litter, which increases soil fertility. Because browsing prevents establishment of aspen regeneration, succession to conifers occurs at a faster pace. When beaver cut down aspen trees near ponds, and subsequent intensive browsing by moose prevents aspen regeneration, balsam fir and spruce become an important component of the forest in the openings.
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.