Crown releasing of red maple poles to shorten high-quality sawlog rotations

The effects of six crown-release treatments on growth and bole quality development of 54-year-old dominant, codominant, and intermediate red maples (Acer rubrum L.) were evaluated on a good red maple site (site index = 19.3 mat 50 years) in upper Michigan. Results showed that crown release stimulated the growth of dominants, codominants, and strong intermediates without appreciably degrading log quality. The heavier 1.5- to 4.6-m crown-release treatments resulted in 7-year average DBH growth increases over the unreleased controls of 70% for dominants, 96% for codominants, and 108% for intermediates. Crown release had no effect on 8-year height growth, 3-year epicormic branching, or bole quality. Three years after treatment, unreleased trees had almost as many epicormic branches as released trees. The number of epicormic branches on individual trees was a function of dominance, log position, or height above ground, but was not related to residual stand density. Epicormic branching was also strongly correlated with the number of pretreatment epicormic branches on boles of intermediate trees, but not on dominant or codominant trees.