When discussing structural southern yellow pine lumber, questions frequently are asked regarding changes over time. This is a significant area of discussion given that structural lumber properties (i.e., design values) were changed around 2012. Climate change, forest management, genetics, processing, and others are listed among the many possible contributing factors. Of interest are these questions: (1) Are changes in bending properties permanent at some fundamental level, or are they somewhat dynamic and responsive to controllable factors? (2) To what degree have the basic southern pine wood mechanical properties changed over time? Related thereto, this research examines the bending properties of small clear pine specimens from three samples. Sample 1 was pulled from a production-weighted sample of in-grade parent lumber. Sample 2 was pulled from commercially available molding and millwork. Sample 3 was pulled from data from the U.S. Department of Agriculture Forestry Products Laboratory from the early to mid-1960s. The flexural properties of small clear specimens among the three samples showed some statistically significant differences. However, there was no clear trend regarding these differences. These results appear to support the notion that while the variability of pine's flexural properties is significant and that while many changes in forest management and production have occurred over the past five decades, the basic density and bending strength of clear southern pine appear generally stable over time.
Bibliographical noteFunding Information:
The authors wish to acknowledge the support of U.S. Department of Agriculture; Research, Education, and Economics; Agriculture Research Service; Administrative and Financial Management; Financial Management and Accounting Division; and Grants and Agreements Management Branch under agreement no. 58-0204-6-001. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture. The authors thank Mississippi State University, College of Forest Resources, Department of Sustainable Bioproducts, and the Forest and Wildlife Research Center. This publication is a contribution of and approved as journal article SB 985 of the Forest and Wildlife Research Center, Mississippi State University.
© Forest Products Society 2021.