Wood and drying properties of white oak from thinned and unthinned plantations

The objective of this study was to examine selected wood and drying properties of white oak (Quercus alba L.) trees removed from plantations in southern Illinois. Trees from two stands, established about 1939, with similar site indexes, were harvested in February 1988. One stand had been thinned in 1973; the other stand had not been thinned. We examined properties of 10 codominant (13- to 14-in. diameter at breast height (DBH)) and 10 intermediate (9- to 10-in. DBH) size trees within each stand. The amount of heartwood among trees within a stand was not significantly different. Heartwood amounts in trees from the unthinned stand averaged 84 percent; amounts in trees from the thinned stand averaged 81 percent. Growth rates and specific gravity (SG) were not significantly different among size groups of trees between stands. As expected, we observed significantly greater diameter growth rate after thinning in the intermediate-sized trees, but did not see this in the codominant trees. Trends in SG from pith to bark were similar regardless of tree size or stand of origin. When boards were dried from green (about 57%) to 7 percent moisture content we observed significant differences in board thickness shrinkage between the thinned stand and unthinned stand. No significant differences were noted in board width shrinkage. Tree size had a greater influence on lumber grades than did stand or management effects.

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