Numerous studies highlighted sharp declines in abundance of red oak species (Quercus spp., Section Erythrobalanus) in the southeastern United States. Red oaks are major components of bottomland forests, provide important ecological services, and are a critical source of hard mast for wildlife and high-value timber (Oliver et al. 2005). Bottomland hardwoods are usually managed with natural regeneration, and maintaining a component of red oak can challenge forest managers, given sporadic acorn production (masting behavior), and lack of advance regeneration establishment prior to disturbance. This study investigated the development of hardwood advance regeneration in relation to understory light availability and stand structure in mature closed canopy stands following silvicultural treatments. Improved understanding of red oak natural regeneration can better clarify any relationship between seedling abundance, available understory light, and residual basal area. Results will aid in selection of appropriate management techniques to sustain dominance of red oaks within bottomland hardwood forests.

Effects of fungi and overstory composition on tree seedling survival and growth were investigated in closed canopy upland forests in the coastal plain of South Carolina. Seedlings of Quercus alba, Cornus florida and Pinus taeda were planted in the understory of two forest types -naturally regenerated hardwood and planted pine. Fungal species composition and biomass were experimentally manipulated with a treatment of the fungicide captan. In contrast with other studies conducted in different systems (sand dune, grassland, and old field), the effects of soil fungi were minor in a closed canopy forest. Only Q. alba showed a significant response to the fungicide (p < 0.05) treatment with increased growth. Overstory composition had no significant effect on growth or survival for any of the species. Both of the commercially desirable species (Q. alba and P. taeda) had reasonable survival ( @ 60%). Both also maintained positive, though modest, growth. This suggests that an advance regeneration pool could be established successfully by artificial regeneration. / Master of Science

The successful regeneration of mature oak (<i>Quercus</i> spp.) forests is thought to be dependent on the presence of oak advance regeneration. However, the advance regeneration must be of sufficient size and density for oak to be competitive and become a dominant species after harvest. The presence of a dense midstory canopy of shade tolerant species has been implicated with the poor development of oak advance regeneration. Understory Vegetation Control was conducted in 1994 in average quality (SI₅₀ 17.7 - 21.9 m for upland oak) southern Appalachian forest stands to determine the effects on oak (<i>Quercus</i> spp.) and maple (<i>Acer</i> spp.) advance seedling abundance, growth, and development. Three study sites were located in southwest Virginia, and the following two treatments were implemented at each site: Understory Vegetation Control (UVC) and Control. Permanent sampling plots and individual seedlings were located to quantify the density, recruitment, and growth of advance regeneration. Competing vegetation was significantly reduced after one year by the UVC treatment, where the mean relative change in the sum of the heights of competing stems between 1 and 5 m in height was -15.9 percent for the UVC plots vs. 22.8 percent for the Control plots. Neither oak seedling recruitment nor height growth was enhanced by the UVC treatment after one year. Insufficient time has elapsed to allow for a growth response, or to determine if seedling recruitment will be enhanced by UVC. Several years may be required to determine if the UVC treatment can enhance the growth and competitive status of oak regeneration. / Master of Science