Diameter growth of upland oaks after thinning

Diameter growth rates of the 40 largest trees per acre on 154 permanent plots in Kentucky, Ohio, Missouri, and Iowa were analyzed to determine the effects of thinning in upland oak stands. The plots were established over a wide range of stocking levels, stand age, and site conditions. Thinning resulted in increased diameter growth of the residual trees, regardless of age or site. The heavier the thinning, the greater the response. Diameter growth rates, and growth response after thinning relative to a control, were better in younger stands. Growth rates were higher on better sites, but the growth response relative to a control was not influenced much by site. In most instances the largest 40 trees per acre responded as well or better to thinning than the second 40 largest.