Ecological and hydrological consequences of beaver activity in Riding Mountain National Park, Manitoba

Landscape and community level effects of beaver disturbance were investigated over a 60-year period in the boreal forest of Riding Mountain, Manitoba. Two sites were studied; both currently support high beaver populations, following reintroduction of the species in 1947. Beaver affect landscapes in two ways: (a) selective harvesting of aspen, altering forest stand structure, composition, and dynamics; (b) beaver damming, creating new wetland habitat. Beaver foraging distance ranged from 24 m to 40 m. Large amounts of timber were harvest by beaver, ranging from 16.4 m2/ha to 20.7 m2/ha (basal area). The number of beaver dams at one site increased from 12 in 1964 to 324 in 2004, resulting in a doubling of wetland habitat to 10% of the landscape. In addition, beaver were found to potentially affect 21-26% of the forested landscape through their foraging activities.