Mechanical and Anatomical Properties in Individual Growth Rings of Plantation-Grown Eastern Cottonwood and Loblolly Pine


  • B. A. Bendtsen
  • John Senft


Plantation grown, anatomical properties, mechanical properties, juvenile wood, mature wood, loblolly pine, eastern cottonwood


Growth in genetically improved trees under intensive management is so rapid that rotations may be as short as 20 to 30 years. At that age, the trees contain a high proportion of lower quality juvenile wood. Thus, the properties of juvenile wood need to be characterized to effectively use this resource.

This study determined relationships between age and mechanical and anatomical properties, the average properties of juvenile and mature wood, the age of demarcation between juvenile and mature wood, and the projected proportions of juvenile and mature wood at various ages in plantation cottonwood and loblolly pine. It also compared projected properties of plantation trees with those published for trees from natural forests.

All properties improved markedly with age, up to nearly a tenfold increase in modulus of elasticity of one loblolly pine tree from early juvenile wood to late mature wood. Average mechanical properties of juvenile wood ranged from 47% to 63% of those for mature wood in pine and from 62% to 79% in cottonwood. The age of demarcation between juvenile and mature wood varied by species and property, ranging from 13 to 20 years. At age 40, plantation trees sampled were projected to contain approximately 25% juvenile wood. The mechanical properties of the pine were projected to approximate those of trees from natural forests at 30 to 60 years, depending on property, while those for cottonwood will not achieve comparability.


American Society for Testing and Materials. 1983. Standard methods for establishing structural grades and related allowable properties for visually graded lumber. ASTM D 245-81, Philadelphia, PA.nBendtsen, B. A. 1978. Properties of wood from improved and intensively managed trees. For. Prod. J. 28(10):61-72.nBohannan, B. 1966. Effect of size on bending strength of wood members. USDA Forest Serv. Res. Pap. FPL 56. For. Prod. Lab., Madison, WI.nHudson, Devek J. 1966. Fitting segmented curves whose join points have to be estimated. J. Am. Stat. Assoc. 61(316):1097-1129.nPercival, D. H., S. K. Suddarth, and Q. B. Comus. 1982. Ceiling-floor partition separation studies. Research Report 82-2, Small Homes Council. Building Research Council. Univ. of Illinois, Urbana-Champaign, IL.nSenft, John F., and B. A. Bendtsen. 1984. Measuring microfibrillar angles using light microscopy. (Manuscript in preparation, Forest Prod. Lab., Madison, WI.)nU.S. Department of Agriculture, Forest Service. 1974. Wood Handbook: Wood as an engineering material. Handbk. 72. For. Prod. Lab., Madison, WI.n






Research Contributions