First-year Changes in Oak Regeneration, Understory Competitors, and Resource Levels in Response to Two Overstory Treatments and Prescribed Burning at Chuck Swan State Forest

Oaks (Quercus spp.) are highly valuable as sources of forest products, in promoting recreation, and in providing food and habitat for wildlife. Oak regeneration has significantly declined over the past century in many regions of the eastern United States. This has led to increased concern with respect to the maintenance of oakdominated ecosystems on the landscape in the future. It is currently thought that oaks are being out competed by species that either grow faster or are more tolerant of shade than oaks. Many of these competitors are more sensitive to fire than oak, and it is thought that human exclusion of fire from the landscape has resulted in an increase in the abundance of these competitors. Prescribed burning, herbicides, and cutting are potential methods of reducing the abundance of competitors, but these methods have not been definitively tested in all regions of the eastern U.S., and have produced mixed results in some cases.

I investigated the effects of four treatments on forest vegetation, particularly impacts on oak species and their primary competitors. These treatments were: shelterwood cutting, wildlife thinning using herbicide, wildlife thinning using herbicide in conjunction with prescribed burning, and prescribed burning with no overstory treatment. Herbs, woody regeneration, and woody stems in the midstory and overstory were all monitored before and after treatment to quantify changes in plant species composition, cover, density, and structure. Post-treatment light and soil moisture were also measured to help explain vegetation responses.

Shelterwood harvests and wildlife thinnings increased understory light availability while showing no statistically significant effects on soil moisture levels. Both treatments significantly reduced overstory cover as well as midstory vegetation. Prescribed fire was found to significantly increase the density of oak seedlings and sprouts < 10-cm tall. Red maple regeneration, the most abundant competitor prior to treatment, was reduced in all size classes by prescribed burning. Two other primary competitors, sassafras and yellowpoplar, were both significantly increased in all regeneration size classes.