Juvenile-Mature Wood Demarcation in Loblolly Pine Trees


  • Gudaye Tasissa
  • Harold E. Burkhart


Segmented model, demarcation age, specific gravity, iterative solution, <i>Pinus taeda</i>


Specific gravity data from loblolly pine (Pinus taeda L.) trees in a region-wide thinning study in southeastern United States were used to determine the age of demarcation between juvenile and mature wood. Segmented modeling, iterative solution, and constrained solution approaches were used to estimate the demarcation age. The results indicated that the age of demarcation between juvenile and mature wood occurs at approximately 11 years of physiological or cambial age (i.e., number of rings from the pith). Constraining the slope of the mature wood equation to a non-negative value lowered the demarcation age typically to less than 10 years. Within-tree variation in the age of demarcation was minor, suggesting that the use of the demarcation age estimate at breast height is adequate when quantifying the proportion of juvenile wood in a tree. Variations in the age of demarcation along the stem due to thinning effects and physiographic region did not show consistent trends. Trees in the Coastal Plain, however, tended to have lower ages of demarcation than trees from other areas.


Abdel-Gadir, A. Y., and R. L. Krahmer. 1993. Estimating the age of demarcation of juvenile and mature wood in Douglas-fir. Wood Fiber Sci. 25(3):242-249.nBendtsen, B. A. 1978. Properties of wood from improved and intensively managed trees. Forest Prod. J. 28(10):69-72.nBendtsen, B. A., and J. Senft. 1986. Mechanical and anatomical properties in individual growth rings of plantation-grown cottonwood and loblolly pine. Wood Fiber Sci. 18(1):23-28.nBurkhart, H. E., D. C. Cloeren, and R. L. Amateis. 1985. Yield relationships in unthinned loblolly pine plantations on cutover, site-prepared tands. S. J. Appl. For. 9:84-91.nClark, A. III, and J. R. Saucier. 1989. Influence of initial planting density, geographic location, and species on juvenile wood formation in southern pine. Forest Prod. J. 39(7/8):42-48.nGallant, A. R., and W. A. Fuller. 1973. Fitting segmented polynomial regression models whose join points have to be estimated. J. Am. Stat. Assoc. 68:144-147.nLoo, J. A., C. G. Tauer, and R. W. McNew. 1985. Genetic variation in the time of transition from juvenile to mature wood in loblolly pine (Pinus taeda L.). Silvae Genet. 34(1): 14-19.nNethr, J., W. Wasserman, and M. H. Kunter. 1989. Applied linear regression models. Richard D. Irwin, Inc. Homewood, IL.nRoos, K. D., J. E. Shottafer, and R. K. Shepard. 1990. The relationship between selected mechanical properties and age in quaking aspen. Forest Prod. J. 40(7/8): 54-56.nSAS Institute Inc. 1985. SAS/STAT guide for personal computers, version 6. SAS Institute Inc., Cary, NC 27513.nSkmke, L. K. 1984. Effects of juvenile pine fibers on kraft paper properties. Pages 160-177 in Proc., Symposium on Utilization of the Changing Wood Resources in the Southern United States. North Carolina State University, Raleigh, NC.nSenft, J. F., and B. A. Bendtsen. 1984. Juvenile wood processing and structural products considerations. Pages 102-108 in Proc., Symposium on Utilization of the Changing Wood Resources in the Southern United States. North Carolina State University, Raleigh, NC.nTalbert, J. T., and J. B. Jett. 1981. Regional specific gravity values for plantation grown loblolly pine in the southern United States. Forest Sci. 27:801-807.nTasissa, G., and H. E. Burkhart. 1998. Modeling thinning effects on ring specific gravity of loblolly pine (Pinus taeda L.) (in press).nThomas, R. J. 1984. The characteristics of juvenile wood. Pages 40-52 in Proc., Symposium on Utilization of the Changing Wood Resources in the Southern United States. North Carolina State University, Raleigh, NC.nYang, K. C., C. A. Benson, and J. K. Wong. 1986. Distribution of juvenile wood in two stems of Larix laricina. Can. J. For. Res. 16:1041-1049.nZobel, B. J., and R. L. McLlwee. 1958. Natural variation in wood specific gravity of loblolly pine, and an analysis of contributing factors. Tappi 41(4):158-161.nZobel, B. J., C. Webb, and F. Henson. 1959. Core or juvenile wood of loblolly and slash pine trees. Tappi 42(5):345-356.nZobel, B. J., R. C. Kellison, M. F. Mathias, and A. V. Hutcher. 1972. Wood density of southern pines. N. Carolina Agri. Exp. Station Tech. Bull. No. 208.n






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