Light patterns align with successful Quercus and Carya regeneration but reveal continued challenges in managing dry-mesic southern Appalachian upland hardwood forests

Field experiments of gap-based silviculture have provided inconsistent evidence that these approaches are effective in regenerating shade midtolerant oaks (Quercus spp.) and hickories (Carya spp.) in upland deciduous forests of the southern Appalachian Mountains, USA. We measured tree regeneration in a long-term field demonstration containing 13-and 30-year-old harvest gaps to evaluate the response of regeneration to group selection harvesting. Oak and hickory regeneration was mapped within the gaps to allow testing for evidence of spatial partitioning among these species. Mixed mesophytic hardwood species accounted for nearly 75% of the regeneration density in both sets of gaps. However, the average combined densities of regenerated oaks and hickories exceeded 900 trees per hectare across all gaps. Oak and hickory regeneration was clustered in the western portion and edges of the 13-year-old gaps but randomly distributed throughout 30-year-old gaps. Light was a significant driver for the spatial partitioning of oaks and hickory regeneration, but other unmeasured factors like interspecific competition from mesophytic hardwoods likely also exerted influence. These results show that oaks and hickories can be regenerated using gap-based silviculture and that their densities may temporarily be highest along the periphery of the gap environment.