Changes in growth dominance after partial cuts in even- and uneven-aged northern hardwood stands

Abstract

The success of partial cut applications to northern hardwood stands is based upon the contribution of harvested and residual trees to overall stand growth, which can be captured by a stand-level criterion, i.e, the growth dominance coefficient (GDC). The main objective of this study was to test the relevance of GDC in evaluating the success of partial cuts in even-aged and uneven-aged stands that were composed of sugar maple (Acer saccharum Marsh.) and yellow birch (Betula alleghaniensis Britt.). We first determined whether GDC that was calculated with two indicators of light capture, stem mass and tree leaf area, produced similar results after partial cutting in both stand structures. Second, using linear mixed models, we determined the effect of selection cutting on GDC in uneven-aged stands over the short- and medium-term, and evaluated effects of tree vigour and size before cutting on diameter growth response of trees after cutting. GDC based upon stem mass was similar to GDC based upon tree leaf area in even-aged stands (p = 0.7200), but was lower in uneven-aged stands (p < 0.001). Selection cutting in uneven-aged stands did not change GDC in the short- (p = 0.7721) and medium- (p = 0.8363) term. Yet, several trees that grew rapidly before cutting responded negatively to partial cutting, while many trees that grew slowly before cutting responded positively. Overall, assessing the success of partial cuts appears to be difficult using GDC, a stand-level criterion. Such assessments, as well as a better understanding of the effects of partial cuts, could be obtained through more detailed growth analyses that are performed at the tree level.