Regenerating oak-dominated forests using irregular, gap-based silvicultural systemsThis article is part of a larger document. View the larger document here.
Throughout the Eastern United States, practitioners have primarily focused on using uniformly applied even-aged approaches to regenerate oak species. Irregular, gap-based silvicultural systems offer an alternative that retains continuous canopy cover, creates heterogeneous forest structure, and provides multiple income flows over a rotation. Although commonly used in Europe, there are few documented applications of these systems in oak forests of North America. Our objective is to establish a region-wide trial of two variants of an irregular group shelterwood system that successively expands gaps outward until the entire stand has been regenerated. Both variants will use cutting cycles that are 10 percent of the rotation length and harvest approximately 20 percent of the area at each entry. Initial gap size for both variants will be 2.0 to 2.2 times the dominant canopy height, and the overstory will be removed in either one or two stages. In addition, the midstory canopy will be removed from areas of the surrounding forest matrix scheduled for harvest in the next cycle for both variants. Soil scarification, competition control, and/or underplanting may be used in areas lacking sufficient advance reproduction. These treatments will create a light gradient extending from the gap center into the surrounding matrix that should allow intolerant species, like yellow-poplar (Liriodendron tulipifera L.) or shortleaf pine (Pinus echinata Mill.), to prevail in areas high in direct beam radiation and oaks to dominate in the diffuse light conditions created on the gap margins and within the surrounding matrix. Successive expansions will release the developing oak reproduction and will result in a stand with a diverse mixture of commercial species.