Manual Cutting of Sitka Alder-Dominated Plant Communities: Effects on Conifer Growth and Plant Community Structure

Abstract

Abstract Five-year growth and survival responses of lodgepole pine and hybrid spruce to manual cutting of Sitka alder were studied in two montane vegetation complexes in interior British Columbia. The effects of brushing on plant community diversity and structure also were examined. Alder cover and height were reduced throughout the 5-year posttreatment measurement period, but this had no effect on growth or survival of either 5- to 7-year-old lodgepole pine growing in the Dry Alder complex or 4- to 7-year-old hybrid spruce in the Wet Alder complex. Moderate alder cover, which was characteristic at these sites, did not appear to inhibit diameter growth of lodgepole pine or spruce. This was supported by competition thresholds for conifer diameter of 30 and 37% alder cover in the Dry Alder and Wet Alder complexes, respectively. In neither complex did manual cutting result in any changes in species richness, species diversity, or structural diversity of the vascular plant community. The results of this study suggest that brushing of Sitka alder is unnecessary for release of healthy lodgepole pine growing on mesic sites in the Dry Alder complex and is ineffective at alleviating growth limiting factors to spruce on Wet Alder sites. West. J. Appl. For. 19(4):277–287.