Effect of silvicultural gap size on 51 year species recruitment, growth and volume yields in Quercus dominated stands of the Northern Cumberland Plateau, USA

This manuscript seeks to further the understanding of how silvicultural gap size affects stand development and growth patterns among species. The authors studied an experiment established more than 50 years ago in oak (Quercus spp.) dominated stands that tested three gap sizes, 0.02 ha, 0.16 ha and 0.46 ha. Statistical analysis addressed stand-level trends associated with tree size, density, and sawtimber volume as well as species recruitment and individual tree growth and volume. Distinct patterns among gap sizes were present in overall structural characteristics including a significant increase in year 51 sawtimber volume with increasing gap size. Data also indicated that conditions present in the different gap sizes had an influence on individual tree size and that the nature of this effect varied among species group. Tree recruitment among the primary species groups, maple (Acer spp.), oak and yellow-poplar (Liriodendron tulipifera L.), was strongly related to gap size and a notable trend with species shade tolerance was present. Results highlighted how shifting species proportions and changes in tree size associated with different gap sizes can alter important stand characteristics that affect management and forest utility within gap-based silvicultural approaches for upland mixed oak forests in the study region.