Efficacy and associated factors of even- and uneven-aged management to promote oak regeneration in the Missouri Ozarks
Oak regeneration problems have been noted in the Missouri Ozarks and elsewhere in the eastern United States. Alteration of disturbance regimes, competition from nonoak species, and high overstory stocking are believed to be major barriers that impede oak regeneration. We studied regeneration in upland oak forests that were harvested by both even-aged (clearcutting) and uneven-aged (single-tree selection and group selection) regeneration methods, focusing on differences in oak regeneration among stands that received alternative harvest treatments. Ten years after treatments, the density of oak regeneration generally increased with increased removal of overstory trees, but only the clearcutting treatment resulted in a statistically significant increase in the density of oak seedlings and saplings over that in the no harvest treatment (the control). There were no differences among treatments in the relative proportions of oak seedlings and saplings as a whole or by size classes among the treatments. Successful oak regeneration after removal of overstory trees highly depends on the number and size of advance oak reproduction and is closely related to site conditions such as aspect and bedrock geology. Both site factors and advance oak reproduction must be considered when a regeneration method to promote oak is chosen. Compared with the uneven-aged methods (single-tree selection and group selection), clearcutting favored the red oak species over the white oak species.