Long-term effects of alternative partial harvesting methods on the woody regeneration layer in high-elevation Quercus rubra forests of the southern Appalachian Mountains, USA

Abstract

High-elevation Quercus rubra forests in the Appalachian Mountains represent a transition zone between temperate mixed-Quercus forests that dominate lower elevations (<1350 m) and Picea-Abies forests at high (>1530 m) elevations. Little information exists specific to the response to disturbance, including timber harvesting, in these forests. In this study, we examined the long-term (22 years) effects of alternative regeneration methods – group selection harvests (GSH) and shelterwood with high (SWH; 9.0 m2/ha) and low (SWL; 5.0 m2/ha) residual basal area, and undisturbed control (CON) – on the development of the regeneration layer in high-elevation Q. rubra forests in the Appalachian Mountains. Treatments affected the density of the regeneration layer (stems ha−1; SPH), but results varied by species group. Density of Q. rubra saplings (stems ≥ 3.8 cm dbh and <10.9 cm dbh) was significantly greater in GSH (250 SPH), SWH (85 SPH), and SWL (121 SPH) than CON (0 SPH). For shade-tolerant species, density averaged 1095 SPH in SWH and SWL and was significantly greater than in CON. Shade-tolerant Acer rubrum was the most abundant species in the sapling layer 22 years post-harvest. Survival of individuals tagged and followed over time was unaffected by treatment, however, height of Quercus seedlings was greatest in treatments with lower residual basal area (GSH and SWL). At Y22, the relatively low density of successfully regenerated Quercus stems in the regenerated stands suggests that additional treatments, including crown-touch release and/or prescribed burning, may be necessary to secure the continued recruitment of Quercus in these high-elevation Q. rubra forests.