Comparison of grade, yield, and mechanical properties of lumber produced from young fast-grown and older slow-grown planted slash pine

Twenty-five 20-year-old, fast-grown slash pine test trees and twenty-five 50-year-old slash pine control trees of similar diameter at breast height were processed through the Temple-Inland Forest Products Co. (formerly Temple EasTex) chip-n-saw headrig at Diboll, Texas. Test tree volume to a 4-inch top averaged about 26.5 cubic ft. per tree, while the control trees averaged about 47 cubic ft. The recovery in sawlog volume from the control trees was about 10 percent greater per tree than the test trees. Almost 55 percent of the test tree sawlog volume was corewood compared to about 16 percent for the controls. The average specific gravity, modulus of rupture, and modulus of elasticity (MOE) were significantly lower for lumber from the test trees, and the values for lumber from the butt logs of both test and controls were higher than that observed for the respective tops. All lumber from the control trees exceeded the adjusted design values for extreme fiber in bending and MOE. Some lumber from the test tree tops failed to meet the adjusted design value for extreme fiber in bending in both the No. 2 and No. 3 Dimension grades. Ninety-two percent fell below the average MOE required for the No. 2 grade and 91 percent fell below that required for No. 3. Eighty-one percent of the test tree butt log lumber failed to meet the average MOE required for either the No. 2 or No. 3 grades.

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