Loblolly pine is increasingly grown on intensively managed plantation forests that yield excellent growth; however, lumber cut from these trees often contains a large percentage of juvenile wood which negatively impacts strength and stiffness. Because of changing forest management and mill practices the design values for visually graded southern pine were updated in 2013 to more accurately account for the material properties available in commerce. This study was undertaken to assess the bending strength and stiffness of loblolly pine lumber from intensively managed stands located on the Georgia Lower Coastal Plain. Eight hundred and forty-one pieces of lumber sawn from 93 trees age 24-33 years were tested in four-point bending according to ASTM International standards. The No. 1 grade MOE 15 (11.9 GPa) was greater than the current (11.0 GPa) design value and comparable to the previous (11.7 GPa) design value. The No. 2 grade MOE 15 (10.6 GPa) was greater than the current (9.7 GPa) design value but slightly less than the previous (11.0 GPa) design values. The No. 3 grade MOE 15 (9.3 GPa) was between the current (9.0 GPa) design value and the previous (9.7 GPa) design value. Altogether, these results point to the MOE 15 mean values being reasonably comparable to the previous design values and currently meeting or exceeding the current design values for visually graded southern pine lumber.
& Key message Loblolly pine (Pinus taeda) logs can be evaluated using acoustic velocity whereby threshold acoustic velocity values can be set to ensure lumber meets specified mechanical property design values for modulus of elasticity. Keywords Design values. Intensively managed plantations. Mechanical properties. Modulus of elasticity. Modulus of rupture. Nondestructive technology. Southern pine. Wood quality Acoustic evaluation loblolly pine logs and lumber
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