Effects of understory vegetation manipulation on hardwood regeneration recruitment and growth in southern Appalachian forests

The successful regeneration of mature oak (Quercus 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 (Quercus spp.) and maple (Acer 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.