REGENERATION PATTERNS IN SILVICULTURAL OPENINGS OF WESTERN GREAT LAKES NORTHERN HARDWOOD FORESTS 15-24 YEARS POST-HARVEST

In managed northern hardwood forests, successful forest regeneration can depend on the application of silvicultural methods tailored to stand-specific recruitment limitations. The objective of this research is to develop a deeper understanding of the factors that interfere with tree regeneration at three long-term, well-replicated experimental canopy gap studies in the upper Great Lakes region, USA. Chapter 2 examines regeneration at a hemlock canopy gap study 18 years post-harvest that included deer exclosures and a gradient of gap sizes. Chapter 3 investigates the spatial patterns of low-density regeneration along gradients of gap size and different levels of legacy-tree retention at two canopy gap studies, 15 and 24 years post-harvest. Our findings indicate that deer exclusion in larger gap sizes may promote the recruitment of browse sensitive species, such as yellow birch (Betula alleghaniensis Britton) and eastern hemlock (Tsuga canadensis L.), into the tallest layers of the regeneration response (Chapter 2). Furthermore, spatial patterns of low-density regeneration did not follow resource gradients at the gap level and legacy-tree retention appeared to moderate the extent of low-density regeneration (Chapter 3). Collectively, these studies suggest that reducing herbivory and retaining legacy-trees where appropriate may help secure a timely and species-rich regeneration response