Effects of scarification disturbance on the seedling and midstory layer in a successional mixed-oak forest

This study investigated whether soil scarification during the presence of abundant white oak (Quercus alba L) acorns and other mast could be used to increase the density of oak reproduction and reduce competitive midstory species in a mid-successional mixed-oak upland forest. The study was conducted in a 7.3 ha forest with a mature oak overstory and a well-developed midstory of sugar maple (Acer saccharum Marsh.) and pawpaw (Asmina triloba Dunal.) in southern Illinois. The soil scarification was conducted in the autumn after acorn dissemination using a crawler tractor with a six-tooth brush rake. One growing season after treatment, significantly higher numbers of oak seedlings, primarily white oak, were present in the scarified plots (5,164 ha ^-1) compared to the control plots (1,273 ha^-1). Seedling density of all other species classes did not differ between treatments. Scarification affected 61% of midstory trees and thus reduced their density and competitive position. Of these trees, 21% of stems were completely removed by the scarification treatment. Results suggest that, in the presence of abundant acorns, scarification may increase the number of new oak germinants in stands lacking advanced oak reproduction. Finally, because scarification increased the density of oak seedlings and reduced competing midstory trees, it can play a role in promoting the establishment of advanced oak reproduction.