Étude des facteurs associés au dépérissement du bouleau à papier en peuplement résiduel après coupe

Following harvesting operations within the Quebec mixedwood region, decadence symptoms are frequently observed on residual paper birch trees, compromising future harvests. Simultaneously, these residual stands are often a constraint to the establishment and growth of valuable regeneration. In the context of intensive forest management and preservation of the conifer component in mixedwood stands, it is important to identify factors associated with paper birch post-logging decadence. Ninety-eight (98) stands were sampled along a partial cutting chronosequence of 1 to 11 years old in order to examine five site variables and six stand variables susceptible of explaining post-logging decadence. Classification and regression tree (CART) models indicated that stand variables, mainly residual basal area and time since harvest, were the best predictor variables of decadence. This study suggests maintaining a basal area of at least 16 m 2 /ha and preserving larger diameter stems when the objective is to maintain healthy paper birch for further harvesting. When the silvicultural objective is to regenerate softwoods, this study recommends keeping a residual basal area after partial cutting of no more than 4 m 2 /ha. Keywords: residual trees, competition, mixed stands, partial cutting, tree regression, regeneration