Predicting flexural properties of dimension lumber from 40-year-old loblolly pine plantation stands

The predictive value of specific gravity (SG), rings per inch, and percent of latewood in relation to the flexural properties (modulus of rupture [MOR] and modulus of elasticity [MOE]) of lumber from thinned and unthinned 40-year-old plantation stands were analyzed using stepwise regression. It was found that none of the lumber properties were influenced by thinning. Using combined data from both stands, prediction equations for the MOR and MOE of 2- by 4-inch, 2- by 6-inch, and 2- by 8-inch dimension lumber from such plantation sawtimber were developed. For the MOR of 2- by 4-inch, 2- by 6-inch, and 2- by 8-inch lumber, significant regressions involving three factors (SG, rings per inch, and percent of latewood), one factor (SG), and one factor (SG), respectively, were found. Also, for the MOE of 2- by 4-inch, 2- by 6-inch, and 2- by 8-inch lumber, significant regressions involving two factors (SG and ring per inch), three factors (SG, rings per inch, and percent of latewood), and two factors (SG and ring per inch), respectively, were established. Moreover, regression equations for MOR versus MOE for the three lumber sizes were derived.

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