Stand and individual tree growth of mature red oak after crop tree management in southern New England: 5-year results

In winter 2003-04, four oak management study areas were established in Connecticut. Each study area had three 0.62-acre treatment plots: B-level thinning, crop tree, and unmanaged. Each plot was located within a 3- to 5-acre area with similar treatment. The mature red oak sawtimber stands had no prior management and were 80 to 112 years old; upper canopy oaks averaged 17.2 inches in diameter at breast height. All trees larger than 4 inches were permanently numbered and measured annually for 5 years. Basal area was reduced from 138 ft2/acre prior to harvest to 77 and 72 ft2/acre on the B-level and crop tree management plots, respectively. For all size classes combined, basal area growth over the next 5 years was greatest in the crop tree plots, followed by B-level thinning, and finally unmanaged controls. Concurrently, sawtimber basal area growth did not differ among treatments and averaged 1.3 ft2/acre/yr, suggesting management can maintain stand volume growth rates. Relative to 5-yr diameter growth of upper canopy oaks on unmanaged plots (0.9 inches), diameter growth increased by 29 percent on B-level thinning and 54 percent on crop tree management plots to 1.1 and 1.3 inches, respectively. Diameter growth increase was related to degree of crown release. Completely released trees grew more than partially released trees, which in turn grew more than trees that were not released.