The role of advanced regeneration at time of partial harvest on tolerant hardwood stands development

Abstract

In tolerant hardwood forests of eastern North America, multiple-aged silvicultural systems rely on advanced regeneration to restock the forests. Evaluation of the long-term influence of advanced regeneration on the mature stand is critical for improving management practices. We used a retrospective approach to evaluate the influence of advanced regeneration present at the time of harvest on the current (2012) stand structure and the quality of the growing stock. The study was carried out in partially harvested stands in northwestern New Brunswick, Canada. Trees were sampled from stands with varying degrees of harvest intensities, times since harvest, and site characteristics. Pre-existing advanced regeneration contributed the bulk of trees in the 10–19 cm diameter class across the stands. In stands with low-intensity harvest, the overstory was dominated by sugar maple (Acer saccharum Marsh.) that originated as advanced regeneration. In stands with high-intensity harvest, however, yellow birch (Betula alleghaniensis Britt.) pre-existing advanced regeneration dominated the overstory. The probability of sugar maple and yellow birch being acceptable growing stock peaked at a diameter at breast height (DBH) of about 30–40 cm, while other species combined peaked at a DBH of around 20–25 cm. Our results suggest that harvest intensities based on the dominant advanced regeneration composition and harvesting systems that minimize the risk of physical damage to advanced regeneration are required to achieve partial harvesting objectives.