Adjusting harvest rules for red oak in selection cuts of Canadian northern hardwood forests

Abstract

To enhance the vigour and quality of high-graded hardwood stands, the removal of low-vigour trees is often prioritized during harvesting operations. However, northern red oak (Quercus rubra L.) is rarely affected by defects that are indicative of imminent decline and, therefore, are less likely to be marked for harvesting. Consequently, the red oak volumes harvested during recent years were considerably lower than the estimated annual allowable cut in the public forests of Quebec, Canada. We used data from Quebec's forest inventory to identify variables associated with low-vigour red oak trees. Three groups of explanatory variables were formed to take into account tree size descriptors, inter-tree competition and stand descriptors. Logistic regression revealed that the probability of occurrence of northern red oak of low vigour increased with increasing tree diameter at breast height and dominance. Also, low-vigour oak trees were more likely to be found in stands in which total red oak basal area was low. A cut-point analysis indicated that the maximum diameter threshold for harvesting red oak ranged between 34 and 46 cm. These criteria could help forest managers formulate species-specific tree-marking rules that integrate the need to increase the red oak component in the harvested volume to a level that is closer to the annual allowable cut volume while maintaining stand vigour.