Flexural Properties of Lumber from Two 40-Year-Old Loblolly Pine Plantations with Different Stand Densities
Keywords:Loblolly pine, lumber, plantations, flexural properties
AbstractThe effects of stand density on the flexural properties and compliance-to-grade requirements of lumber from two 40-year-old loblolly pine plantations were evaluated. The results indicate that stand density is positively influencing the flexural stiffness and grade compliance of the lumber produced from these plantations. On the other hand, stand density had no effect on the flexural strength of the lumber from these plantations. The lumber from the denser 40-year-old stand, which had 28 m/50 yr site index, 2.4-by 2.4-m original spacing, never thinned, with 679 trees/ha and 11.4-sq m basal area at harvest, has 96% and 66% compliance to required flexural strength and stiffness values, respectively. The lumber from the thinned 40-year-old stand, with 28 m/50 yr site index, 2.4-by 2.4-m original spacing, thinned at age 25, with 450 trees/ha and 10.2-sq m basal area at harvest, has 96% and 53% compliance to required flexural strength and stiffness values, respectively. It is now evident from the results of these studies that even dense stands must be older than 40 years of age before they can be harvested for lumber production to ensure attainment of at least 95% lumber grade compliance, i.e., strength and stiffness values that are consistent with assigned visual grades.
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