• Mark Alexander Butler University of Georgia
  • Joseph Dahlen University of Georgia
  • Finto Antony
  • Michael Kane
  • Thomas L Eberhardt
  • Huizhe Jin
  • Kim Love-Myers
  • John Paul McTague


mechanical properties, modulus of elasticity, modulus of rupture, nondestructive testing, southern pine, wood quality


Prior to the 1980s the allowable stresses for lumber in North America were derived from testing of small clear specimens but the procedures changed because these models were found to be inaccurate.  Nevertheless, small clear testing continues to be used around the world for allowable stress determinations and in studies that examine forest management impacts on wood quality.  Using small clears and nondestructive technologies is advantageous because of the ease of obtaining and testing small clear specimens compared to lumber.  The objective of this study was to compare the mechanical properties in bending of small clear specimens with lumber specimens for loblolly pine.  Eight hundred and forty-one pieces of lumber in the No. 1 to No. 3 grades and 2×4 to 2×10 sizes were collected from a forest-thru-mill study and tested in static bending.  A small clear specimen (25 x 25 x 410 mm) was prepared from each piece of lumber and tested in static bending.  The effect of growth ring orientation was explored and overall samples tested on the radial or rift face did a better job of explaining the variation in lumber than samples tested on the tangential face; however, the relationships were generally poor for the modulus of elasticity (MOE) (R2 = 0.22) and modulus of rupture (MOR) (R2 = 0.11) pooled data.  A lumber-based multiple regression model explained 44% and 37% of the variability for MOE and MOR, respectively; whereas a stand-based multiple regression model explained 41% and 29% of the variability for MOE and MOR, respectively.

Author Biographies

Mark Alexander Butler, University of Georgia

Graduate Student

Warnell School of Forestry and Natural Resources

Joseph Dahlen, University of Georgia

Assistant Professor

Warnell School of Forestry and Natural Resources

Finto Antony

Research Scientist and Project Leader

Michael Kane

Graduate Student

Statistical Consulting Center

Thomas L Eberhardt

Associate Director

Statistical Consulting Center

Huizhe Jin


Kim Love-Myers

Former Assistant Research Scientist

Warnell School of Forestry and Natural Resources

John Paul McTague

Professor Emeritus

Warnell School of Forestry and Natural Resources


Adamopoulos S (2002) Flexural properties of black locust (Robinia pseudoacacia L.) small clear wood specimens in relation to the direction of load application. Holz Roh-Werkst 60:325-327.

American Lumber Standards Committee (ALSC) (2013) American Lumber Standard Committee Board of Review: Board of Review Minutes. February 1, 2013. American Lumber Standards Committee, Germantown, MD.

Antony F, Jordan L, Daniels RF, Schimleck LR, Clark A, Hall DB (2009) Effect of midrotation fertilization on growth and specific gravity of loblolly pine. Can J For Res 39(5): 928-935.

Antony F, Schimleck LR, Daniels RF, Clark A, Hall DB (2010) Modeling the longitudinal variation in wood specific gravity of planted loblolly pine (Pinus taeda) in the United States. Can J For Res 40: 2439-2451.

Antony F, Jordan L, Schimleck LR, Clark A, Souter RA, Daniels RF (2011) Regional variation in wood modulus of elasticity (stiffness) and modulus of rupture (strength) of planted loblolly pine in the United States. Can J For Res 41:1522-1533.

ASTM International (2010) ASTM D2915-10: Standard practice for evaluating allowable properties for grades of structural lumber. West Conshohocken, PA.

ASTM International (2011) ASTM D245-06(2011): Standard practice for establishing structural grades and related allowable properties for visually graded lumber. West Conshohocken, PA.

ASTM International (2011) ASTM D2555-06(2011): Standard practice for establishing clear wood strength values. West Conshohocken, PA.

ASTM International (2013) ASTM D4761-13: Standard test methods for mechanical properties of lumber and wood-base structural material. West Conshohocken, PA.

ASTM International (2014) ASTM D143-14: Standard test methods for small clear specimens of timber. West Conshohocken, PA.

ASTM International (2014) ASTM D198-14: Standard test methods of static tests of lumber in structural sizes. West Conshohocken, PA.

ASTM International (2014) ASTM D1990-14: Standard practice for establishing allowable properties for visually-graded dimension lumber from in-grade tests of full-size specimens. West Conshohocken, PA.

Auty D, Achim A (2008) The relationship between standing tree acoustic assessment and timber quality in Scots pine and the practical implications for assessing timber quality from naturally regenerated stands. Forestry. 81(4):475-487.

Biblis EJ (1971) Flexural properties of southern yellow pine small beams loaded on true radial and tangential surfaces. Wood Sci Tech 5:95-100.

Borders BE, Bailey RL (2001) Loblolly pine – pushing the limits of growth. South J Appl For 25:69-74.

Briggs D (2010) Enhancing forest value productivity through fiber quality. Journal of Forestry 108(4): 174-182.

British Standards Institute (BSI) (1957) Methods of Testing Small Clear Specimens of Timber. British Standards Institute, London, p. 24 BS373:1957.

Butler A, Dahlen J, Daniels RF, Eberhardt TL, Antony F (2015) Bending strength and stiffness of loblolly pine lumber from intensively managed stands located on the Georgia Lower Coastal Plain. Accepted: Eur J Wood Prod.

Clark III A, Daniels RF, Jordan L (2006) Juvenile/mature wood transition in loblolly pine defined by annual ring specific gravity, proportion of latewood, and microfibril angle. Wood Fiber Sci 38(2):292-299.

Clark III A, Jordan L, Schimleck L, Daniels RF (2008) Effect of initial planting spacing on wood properties of unthinned loblolly pine at age 21. Forest Prod J 58(10):78-83.

Cown DJ, Clement BC (1983) A wood densitometer using direct scanning with x-rays. Wood Sci. Technol 17:91-99.

Cown DJ, Hebert J, Ball R (1999) Modeling pinus radiata lumber characteristics. Part 1: mechanical properties of small clears. New Zealand Journal of Forestry Science 29(2): 203–213.

de Mendiburu F (2014) Agricolae: Statistical Procedures for Agricultural Research. R package version 1.1-8.

Doyle DV, Markwardt LJ (1966) Properties of southern pine in relation to strength grading of dimension lumber. US For. Serv. Forest Products Laboratory. FPL-64.

Evans R (1999) A variance approach to the x-ray diffractometric estimation of microfibril angle in wood. Appita J 53:283-289.

Evans JW, Kretschmann DE, Herian VL, Green DW (2001) Procedures for developing allowable properties for a single species under ASTM D1990 and computer programs useful for the calculations. USDA Forest Service. Forest Products Laboratory. FPL-GTR-126.

Forest Products Laboratory (FPL) (2011) NONPAR: Nonparametric estimation program. . Accessed September 26, 2011.

Gastwirth J, Gel YR, Hui WLW, Miao W, Noguchi K (2015) Lawstat: Tools for biostatistics, public policy, and law. R package version 2.5

Glass SV, Zelinka SL (2010) Moisture relations and physical properties of wood. Pages 4-1-4-19 in RJ Ross, ed Wood Handbook. USDA Forest Service. Forest Products Laboratory. FPL-GTR-190.

Green DW, Shelley BE, Vokey HP (1989) In-grade testing of structural lumber. In: Proceedings of workshop sponsored by In-grade Testing Committee and Forest Products Society. Proceedings 47363. Madison, WI: Forest Products Society.

Grotta AT, Leichti RJ, Gartner BL, Johnson GR (2005) Effect of growth ring orientation and placement of earlywood and latewood on MOE and MOR of very-small clear Douglas-fir beams. Wood Fiber Sci 37(2):207-212.

Ivovic M, Gapare WJ, Abarques A, Ilic J, Powell MB, Wu HX (2009) Prediction of wood stiffness, strength, and shrinkage in juvenile wood of radiate pine. Wood Sci Technol 43:237-257.

Jayawickrama KJS (2001) Breeding radiata pine for wood stiffness: Review and Analysis. Australian Forestry 64: 51-56 .

Jones PD, Schimleck LR, Peter GF, Daniels RF, Clark A (2005) Nondestructive estimation of Pinus taeda L. wood properties for samples from a wide range of sites in Georgia. Can J For Res 35:85-92.

Jordan L, Clark III A, Schimleck LR, Hall DB, Daniels RF (2008) Regional variation in wood specific gravity of planted loblolly pine in the United States. Can J For Res 38:698-710.

Kretschmann DE, Bendtsen BA (1992) Ultimate tensile stress and modulus of elasticity of fast-grown plantation loblolly pine lumber. Wood Fiber Sci 24(2):189-203.

Kretschmann DE, Green DW (1996) Modeling moisture content-mechanical property relationships for clear southern pine. Wood Fiber Sci 28(3):320-337.

Kretschmann DE (2010) Mechanical properties of wood. Pages 5-1-5-46 in RJ Ross, ed Wood Handbook. US For Serv. Forest Products Laboratory. FPL-GTR-190.

Larson PR, Kretschmann DE, Clark III A, Isebrands JG (2001) Formation and properties of juvenile wood in southern pines. US For Serv. Forest Products Laboratory. FPL-TR-129.

Madsen B (1992) Structural behavior of timber. Timber Engineering Ltd. North Vancouver, British Columbia Canada.

McAlister RH, Clark III A (1991) Effect of geographic location and seed source on the bending properties of juvenile and mature loblolly pine. Forest Prod J 41(9):39-42.

McKeand S, Mullin T, Bryam T, White T (2003) Deployment of genetically improved loblolly and slash pines in the South. J Forestry 101(3):32-37.

Moya L, Laduarda MF, Cagno M, Cardosa A, Gatto F, O’Neill H (2013) Physical and mechanical properties of loblolly and slash pine wood from Uruguayan plantations. Forest Prod J 63(3/4): 128-137.

Munsell JF, Fox TR (2010) An analysis of the feasibility for increasing woody biomass production from pine plantations in the southern United States. Biomass Bioenergy 34(2010):1631-1642.

Mora CR, Shimleck LR, Isik F, Mahon Jr. JM, Clark III A, Daniels RF (2009) Relationships between acoustic variables and different measures of stiffness in standing Pinus taeda trees. Can J For Res 39:1421-1429.

Norris Foundation (2014) Timber Mart-South State Timber Price Reports. Center for Forest Business, Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA.

R Core Team (2014) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL

RStudio (2014) RStudio: Integrated development environment for R (Version 0.98.932). Boston, MA. Retrieved April 17, 2014.

Schimleck LR, Reinhard S, Mora C, Jones PD, Daniels RF (2005) Comparison of Pinus taeda L. wood property calibrations based on NIR spectra from the radial-longitudinal and radial-transverse faces of wooden strips. Holzforschung 59:214-218.

USDA Forest Service (1988) The South’s fourth forest; alternative for the future. US For Serv., Forest Resou. Rept. 24. U.S. Gov. Print. Office. Washington, D.C. 512 pp.

Vance ED, Maguire DA, Zalesney Jr. RS (2010) Research Strategies for Increasing Productivity of Intensively Managed Forest Plantations. J Forestry. 183-192.

Vikram V, Cherry ML, Briggs D, Cress DW, Evans R, Howe GT (2011) Stiffness of Douglas-fir lumber: effects of wood properties and genetics. Can J For Res 41:1160-1173.

Wessels CB, Malan FS, Rypstra T (2013) A review of measurement methods used on standing trees for the prediction of some mechanical properties of timber. Eur J Forest Res 130:881-893.

Winston C (2014). extrafont: Tools for using fonts. R package version 0.17.

Yang BZ, Seale RD, Shmulsky R, Dahlen J, Wang X (2015) Comparison of nondestructive testing methods for evaluating No. 2 southern pine lumber: modulus of elasticity. In Review: Wood and Fiber Science.






Research Contributions