Sawtimber production with thinning in stratified, mixed-species, even-aged northern hardwoods

Conventional thinning guidelines aimed at increasing high-quality sawtimber production may not directly account for vertical strata in canopy that form due to the species mixture. Strata effects on thinning for sawtimber production were compared in 12, 0.1-acre, 65- to 70-year-old, unthinned plots in northwestern Pennsylvania. Plots were thinned using 13 simulated combinations of relative density and structural manipulations and projected for 15 years using a computer program (SILVAH). Board-foot volume production and medial diameter of the merchantable class (MDM) were compared among thinning trials for each plot. Three of the 12 plots were identified to have significant board-foot volume and/or MDM increases when thinned with sensitivity to strata as compared to conventional thinning techniques. Foresters are reminded to adjust for stratified areas when thinning to foster sawtimber production.