Enhancing Establishment of White Oak and American Hazelnut Enrichment Plants in a Mesic Forest Using Understory Removal and Group Selection

In the absence of periodic disturbance, primarily fire, many oak-dominated woodlands in the Eastern and Midwestern United States are transitioning to sugar maple (Acer saccharum) dominated communities. This experiment was conducted to determine the effects of forest overstory and/or understory removals on enrichment plantings of white oak (Quercus alba) and American hazelnut (Corylus americana). The combination of prescribed forest canopy openings and understory tree removal significantly increased mean twig elongation, an indicator of overall growth and vigor, of white oak as compared to control trees. A similar pattern was seen in the hazelnut, with the two treatments that included a group selection opening offering a significant growth advantage over the treatment which only included understory clearing. Group selection openings in this study were small (250 m²) compared to previously recommended canopy openings of 1,000 m² or more, suggesting that oak and hazelnut regeneration may be enhanced without the dramatic visual impact of more intense silvicultural practices of clearcutting and shelterwood and when using large planting stock (> 1.5 m in height or 2.5 cm caliper for oak and 3–4 year old containerized hazelnut). As such, successful oak and hazelnut establishment and growth may be possible in intensively managed, frequently visited forest preserves where maintaining site aesthetics is a high priority.