No abstract

Performance of northern red oak (Quercus rubra) underplantings under five management regimes and across existing environmental gradients Adam E. Regula Oaks (Quercus sp.) are dominant throughout much of the eastern broadleaf forests of the United States and are of great ecological, economical, and cultural value. Despite their prevalence in the overstory, many sites are lacking in the advanced reproduction necessary for its regeneration in future stands. This dilemma has merited much research, but widely applicable and consistently successful methods for regenerating oak remain elusive. This study examines the response of northern red oak (Q. rubra) underplantings to forest management regimes across the environmental gradients of physiographic province, aspect, and fencing levels. Management regimes included 1) control sites, 2) a single prescribed burn, 3) repeat prescribed burns 5) diameter-limit cuts and 4) the seedcut of a shelterwood harvest. Physiographic provinces included the Ridge and Valley and Appalachian Plateau. The direct relationships between seedling performance and light as well as light and stand structure are also addressed. Seedling growth and survival are found to be driven by a combination of factors. The interaction of physiographic province and management regime exerted a significant influence on seedling survival. While high survival rates were present on sites receiving diameter-limit cuts and shelterwood cuts regardless of province, underplantings experienced a more dramatic drop in survival on single burn and control sited in the Appalachian Plateau than Ridge and Valley. Sapling density appears as stronger limiting factor of light levels on the more mesic Appalachian Plateau sites, and low survival on these sites reflected this. In contrast, the less dense sapling layer and generally higher light levels of the Ridge and Valley enabled underplanted seedlings to better persist here in the absence of overstory removal. The interaction of fencing and physiographic province was significant as well. Deer, were more problematic in this province, and the potential for herbivory to interfere with seedling response to increased resources was evident. Ultimately, the relatively brief duration of the study limits conclusions on the future of these underplantings, but results reinforce the importance of regional differences in forest composition and structure in determining the effectiveness of prescriptions. An awareness of this is particularly important when considering underplanting. v CONTENTS INTRODUCTION and BACKGROUND .