Canopy gaps increase species-dependent edge tree diameter growth in a mature southern Appalachian mixed hardwood forest

Abstract

Understanding the response of tree species to disturbance is critical as climatic variability is projected to shift disturbance regimes, species distribution, and carbon allocation in the eastern US. Altered resource availability and microclimatic drivers bordering canopy gap edges may enhance tree growth. Our objective was to evaluate how this gap edge effect varies across dominant species groups in a southern Appalachian mixed hardwood forest. We assessed the effect of silvicultural canopy gaps, 0.15–1.09 ha in area, on overstory tree diameter growth four years after gap harvest. Increment cores were collected from 288 mature trees across five species groups. Annual ring width was measured across an eight-year timespan to determine how percent change in average annual growth post-harvest varied with distance from gap edge compared to unmanaged control areas. We found that edge tree growth response was significantly greater than matrix and control tree response, with an average percent change in ring width of 48.1 ± 6.0 % at gap edge and 8.9 ± 4.1 % in the forest matrix. There were no significant effects from gap size or azimuth relative to gap center. Red maple had a higher growth response than oak groups, with hickory and tulip-poplar falling in between. These results highlight the importance of species composition in stand-level growth response to disturbance as diffuse-porous species like red maple and tulip-poplar use more water than ring-porous species like oaks.

Citation

Reddy, S.C., Arteman, M.L., Forrester, J.A., Keyser, T.L. 2025. Canopy gaps increase species-dependent edge tree diameter growth in a mature southern Appalachian mixed hardwood forest. Forest Ecology and Management 595: 123008.