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Abstract
The goal of this study was to investigate the effects of thinning and fertilization on mechanical properties of loblolly pine (Pinus taeda L.) strands associated with growth ring number and height. A systematic link to forest management, anatomical properties, and mechanical properties was obtained by correlating the test results with anatomical properties. The modulus of elasticity (MOE) and ultimate tensile strength (UTS) of strands from three loblolly pine trees increased with the increment in growth ring number, whereas the MOE and UTS showed different trends with the increment in height. Prediction of the MOE and UTS with specific gravity for the trees seemed to be unreliable. A natural tree had the greatest correlation between tangential latewood cell wall thickness and the mechanical properties. A thinned tree had the greatest correlation between ring width and the mechanical properties. A fertilized tree had the greatest correlation between density and the mechanical properties. However, the correlation between a specific anatomical property and mechanical properties was weak. Different combinations of anatomical properties predicted MOE and UTS of loblolly pine strands from different forest-managed trees more closely, indicating an R2 of 0.84 to 0.95.
The efficient utilization of woody biomass can be maximized by manufacturing engineered wood products instead of solid lumber due to substantial increases in yield from a log. For example, compared with a 40 percent yield in solid lumber from a log, parallel strand lumber, laminated strand lumber, and oriented strandboard can yield 65, 75, and about 80 to 90 percent, respectively (Schuler and Adair 2000, Balatinecz and Kretschmann 2001). Concurrently an increased demand for engineered wood products has led to increased utilization of small-diameter plantation trees that have received various management strategies to improve tree stem and wood qualties.
Many researchers have studied the effects of forest management on loblolly pine (Pinus taeda L.) wood anatomy (Bendtsen 1978; Taylor and Burton 1982; Megraw 1985; Bentdsen and Senft 1986; Cave and Walker 1994; Tasissa and Burkhart 1998; Groom et al. 2002; Jeong and Zink-Sharp 2012, 2013; among many others). Jeong and Zink-Sharp (2012, 2013) analyzed the effects of thinning and fertilization on the anatomical properties of young loblolly pine at different growth ring numbers and heights. Regardless of the effects of forest management, density increased...