Trembling aspen removal effects on lodgepole pine in southern interior British Columbia: Ten-year results

Abstract

Manual cutting treatments are routinely applied to release lodgepole pine (Pinus contorta var. latifolia Engelm.) from trembling aspen (Populus tremuloides Michx.) competition in southern interior British Columbia. We studied the effects of this treatment on pine and an aspen-dominated community on three sites in the Interior Douglas-Fir and Montane Spruce biogeoclimatic zones. After 10 years, when stands were 17-20 years old, treated aspen was significantly shorter than control aspen, and treated pine had significantly (21%) larger diameter than control pine. There were few other differences between brushed and unbrushed pine, and survival was excellent (≥97%), regardless of treatment. Brushing nearly doubled the average density of conifer stems that were free-growing according to legislated standards, but results were variable, and the free-growing status of the stand was changed on only one site. Regression analysis was used to examine the correlation between aspen abundance and pine size. The density of aspen at least as tall as the pine (tall aspen) predicted 36.2% of the variation in pine diameter, and total aspen density predicted 35.9% of the variation in pine height. An average density threshold of 1,867 tall aspen stems/ha, above which pine stem diameter declined, was identified in the three stands. Copyright © 2009 by the Society of American Foresters.