Fifth-Year Response to Thinning in a Water Oak Plantation in North Louisiana

A 21 ac, 28-yr-old water oak (Quercus nigra L.)plantation, on an old-field loessial site in north Louisiana, was subjected to three thinning treatments during the winter of 1987-1988: (I) no thinning, (2) light thinning to 180 dominant and codominant trees/at, and (3) heavy thinning to 90 dominant and codominant trees/at. Prior to thinning, the plantation averaged 356 trees/at and 86@/ac of basal area, with a quadratic mean diameter of 6.7 in. Thinning reduced stand basal areas to 52 and 34ft2/ac for the light and heavy thinning treatments, respectively. After 5 yr, both thinning treatments increased diameter growth rates of individual residual trees, both when all trees were considered and when the analysis was limited to dominant and codominant trees only. Neither thinning treatment affected either stand-level volume growth or total yield 5 yr after treatment. However, thinning distributed total volume growth among fewer trees, such that, when trees of all crown classes were considered in the analysis, average annual volume growth per tree increased with increasing intensity of thinning. Both basal area growth and volume growth following light thinning appear to be su..cient to promote rapid recovery of the stand to a fully stocked condition in the nearfuture. In contrast, heavy thinning reduced density to a severely understocked condition that will prohibit optimum occupancy of the site for a long period. Among the treatments evaluated in this study, light thinning produced the most desirable combination of individual-tree diameter growth and stand-level basal area growth. South. J. Appl. For. 25(1):31-39.