Modeling strength and stiffness of intensively managed loblolly pine plantations in the Atlantic Coastal Plain of Georgia

Strength and stiffness, or modulus of rupture (MOR) and modulus of elasticity (MOE), are critical properties in determining how well lumber perform in structural applications. Intensively grown, plantation loblolly pine (Pinus taeda) has lower MOR and MOE than that of slower grown trees when harvested with similar dimensions, based on recent research by the Southern Pine Inspection Bureau (SPIB). A total of 93 trees were harvested from the Atlantic Coastal Plain of Georgia, and were processed at a lumber mill into nominal 2 inch wide material (ex. 24). After nondestructively and destructively sampling the lumber from the trees, a model predicting MOE was generated for several scenarios and stages of the harvesting and milling process. The most basic model predicts the MOE of each log from its acoustic velocity measurement (R2 = 0.52). Knowing certain tree or log characteristics, such as diameter at certain points up the bole, age, and height can increase the ability to predict MOE and MOR. A model that predicts MOE from log position, specific gravity, and several diameter measurements, as well as the acoustic velocity of each log had an R2 of 0.70. This relationship suggests that lumber mills could use acoustic velocity as a MOE predictor to sort higher quality logs.