S2A 14-year-old mixed oak stand was thinned in 1977 to stocking levels of 30, 50, and 60 percent and a control. From this stand, 117 trees were selected and their stem-related defects recorded. Six years later these same trees were reevaluated. The number of limb defects per square foot of surface area increased substantially more in the heavily thinned plots than in the unthinned plots. Trends in these data confirm commonly held beliefs that stand density affects stem quality after only a few years.S3.

S2Describes changes in limb-related defects on 18-year-old, even-aged hardwoods 6 years after thinning. Stocking levels of 30, 45, and 60 percent were studied. There were fewer defects per square foot of surface area in the higher stocking plots than in the lower stocking plots. The average number of live limbs decreased by 83 percent in the unthinned plots and increased slightly in the heavily thinned plots. The results show that the frequency and size of limb-related defects are affected by stand density over a short period of time.S3.

"Relative change of several types of stem defects was studied over an 8-year period to determine the effects of crop-tree thinning on the development of tree quality. Special interest was given to changes in relative quality associated with defect indicators of crop trees compared to trees in unthinned plots. The relative quality classes of the crop trees went from "poor" to "medium" for red maple and "poor" to "good" for aspen. The oaks stayed in the poor classification and yellow-poplar remained unchanged in the medium classification. Results showed a decrease in the number of epicormic branches on the crop trees, and an increase in the size of live limbs.S3.