Current and Long-Term Effects of Ungulate Browsing on Aspen Stand Characteristics in Northern Lower Michigan

摘要

The Michigan Department of Natural Resources' (MDNR) objectives for the Pigeon River Country State Forest (PRCSF) and surrounding state lands provide for multiple uses of natural resources. In the 1980's natural resources managers expressed concern over the potential effects of browsing by white-tailed deer (Odocoileus virginianus) and elk (Cervus elaphus nelsoni) on the regeneration of aspen (Populus spp.) stands. Research during the 1980s showed that initial (4-6 year) impacts of ungulate use included decreases in aspen stem densities and vegetation cover, and altered plant species composition. At that time, however, there was no evidence to suggest that ungulate use would have an impact on timber production in the future. To date, the long-term (up to 30-40 years) effects of browsing on stand characteristics and merchantable timber production have not been evaluated. Additionally, current elk densities in some portions of the elk range may be higher than those observed in the mid-eighties, and the effect of this increase on aspen regeneration is uncertain. This study was initiated to determine the current level of browsing compared to historic utilization and to evalaute the potential long-term effects of ungulate use on aspen stand structure and composition.