Impact of Bark Stripping by Moose on Aspen-Spruce Communities

Publisher Website
Google Scholar
Abstract
We studied bark stripping by moose (Alces alces) in Denali National Park and Preserve (DNPP), Alaska, to determine the proportion of bark in the diet, consider what conditions induce bark stripping, and assess the combined impacet of stem breakage and bark stripping in a quaking aspen (Populus tremuloides)-white spruce (Picea glauca) community. Less than 4% of the diet was composed of aspen and willow (Salix spp.) bark. Spring protein content of browse was 3 .times. that of bark. Moose appeared to eat bark when availability of browse was low. Bark stripping was most common among female moose in spring, when movements were restricted by limited mobility of their calves. Over 75% of the aspen and bebb willow (S. bebbiana) canopy trees in an aspen-spruce community were debarked by moose. The amount of bark removed and the percentage of the trunk circumference girdled were positively associated with mortality of aspen and balsam poplar (Populus balsamifera). In the understory, stem breakage by moose increased the probability of deciduous plant mortality. Moose may be increasing the rate of succession in the aspen-spruce community through deciduous tree mortality due to dark stripping and suppression of understory replacement through stem breakage.