Precommercial Crop Tree Release Increases Upper Canopy Persistence and Diameter Growth of Oak Saplings

The effects of precommercial crop tree release (CTR) on growth and stem quality of red oaks (7–22 years old) were examined on seven study areas established in Connecticut in 1988. The three treatments were uncut control, trees given one crown-touching release, and trees released a second time 5 years after the initial release. Diameters and crown classes were measured annually. Heights were measured in 1988–1994, 2001, and 2012. Bole quality measurements were completed in 1989 and 2011. CTR of oak saplings increased upper canopy persistence (remaining in dominant or codominant crown class) and diameter growth with no loss of height growth or increased number of branches on the lower bole. Upper canopy persistence of codominant oaks was 80% compared with 50% for untreated stems. Trees released twice had diameters 1.5 in. greater than unreleased trees with no increased taper. Heights 24 years after release did not differ among treatments. The presence and number of branches on the lower bole did not differ among treatments in 2011. Precommercial crop tree release provides a management tool to (1) increase the number of oaks that will form part of the mature forest in sapling stands that have few oaks or (2) focus growth on oaks with quality stems in sapling stands with abundant oak.