Grade Recovery, Value, and Return-To-Log for the Production of NZ Visual Grades (Cuttings and Framing) and Australian Machine Stress Grades


  • Robert L. Beauregard
  • Rado Gazo
  • Roderick D. Ball


The objective of this study is to link radiata pine tree characteristics to the quality and value of boards in New Zealand (NZ) Cuttings, NZ Visual Framing, and Australian Machine Stress Grades (MSG) from both clonal and standing tree perspectives. Specifically, this paper presents an analysis of clonal variation in the quality and value of 2 X 4s, establishes the relationships between the tree and products characteristics, and documents the broad sense heritability of the tree variables associated with products value.

Ten clones were selected to cover a broad range of radiata pine representative of the forest being harvested in New Zealand in the coming years. Two trees were harvested for each clone. The trees were pruned up to 4 m. The stems were cut into logs, and four logs were cross-cut to be sawn: the pruned butt log and three unpruned. The yield analysis was performed separately for pruned and unpruned logs. Tree quality assessed included DBH, Branch Index, Internode Index, bulk density, outer wood density (from increment cores), ring width, microfibril angle, spiral grain, tracheid length, and compression wood. On the lumber pieces, knot area ratio was also assessed.

The value of boards in NZ Cuttings from pruned butt logs averaged 310 $/m3 as compared to 204 $/m3 for unpruned upper logs. These were significant differences between clones for pruned butt logs and for the boards from unpruned upper logs. Regression analysis confirmed that for NZ Cuttings, small trees with lots of small branches perform badly when compared to large trees with larger branches. Regression analysis also showed that for boards from unpruned upper logs, the longer the internode length, the better the yield in NZ Cuttings.

The value of boards in NZ Visual Framing from pruned butt logs averaged 333 $/m3 as compared with 227 $/m3 for unpruned upper logs. There was no significant difference between clones for boards from the pruned butt logs (P = 0.12), but there were highly significant differences between boards from unpruned upper logs. Regression analysis showed that best performing clones among the unpruned upper logs were the ones with small branches.


Beauregard, R., R. Gazo, M. O. Kimberley, J. Turner, S. Mitchell, and A. Shelbourne. 1999. Clonal variation in the quality of radiata pine random width boards. Wood Fiber Sci. 31(3):222-234.nBier, H. 1986. Log quality and the strength and stiffness of structural timber. NZ J. Forestry Sci. 16(2): 176-86.nBier, H. 1985. Bending properties of structural timber from a 28-year-old stand of New Zealand Pinus radiata.NZ J. Forestry Sci. 15(2):233-50.nBriggs, D. G. 1992. Models linking silviculture, wood quality and product value: A review and example of U.S. coastal Douglas-fir. Pages 285-294 in IUFRO All Div. 5 Conference Forest Products, 23-28 August 1992. Nancy, ARBOLOR ed. Nancy, France.nDunlop, J. 1995. Permanent sample plot system user manual. FRI Bull. No. 187. Forest Research Institute, Rotorua, New Zealand.nEllis, J. C. 1982. A three-dimensional formula for coniferous log volumes in New Zealand. FRI Bull. No. 20. NZ Forest Service.nGazo, R., R. Beauregard, M. O. Kimberley, and D. McConchie. 2000. Incidence of defects by tree characteristics in radiata pine random-width boards. Forest Prod. J. 50(6):83-89.nGeorge, J. W. K., and L. A. Donaldson. 1996. Variation in microfibril angle among ten clones for assessment of value recovery. Project Record No. 5425. NZ Forest Research Institute.nGrant, D. 1987. The grading of timber using the Computermatic Stress Grading Machine. Forestry Commission of New South Wales, Australia.nHarris, J. M. 1966. A method of minimising observer bias in measuring tracheid length. Royal Micros. Soc. 86:81-83.nHaslett, A. N., I. G. Simpson, and M. O. Kimberley. 1991. Utilisation of 25-year-old Pinus radiata. Part 2: Warp of structural timber in drying. NZ J. Forestry Sci. 21(2/3):228-34.nHoullier, F., J. M. Leban, and F. Colin. 1995. Linking growth modelling to timber quality assessment for Norway spruce. Forest Ecol. Mgmt. 74(1995):91-102.nMcKinley, R. B., D. L. McConchie, and B. G. Ridoutt. 1996. Wood properties of ten 27-year-old radiata pine clones grown in Kaingaroa forest. Value Recovery Report, Programme 2, Project 1, Linking tree characteristics to products characteristics, 22 pp.nPalmer, G., K. Harding, and G. Stinger. 1996. An overview of the FWPRDC project—Breeding objectives and tree selection criteria to maximise the value of sawn timber. CSIRO Conference on Wood Processing, November 1996, Melbourne, Australia. 14 pp.nShelbourne, C. J. A., J. M. Harris, J. R. Tustin, and I. D. Whiteside. 1973. The relationship of timber stiffness to branch and stem morphology and wood properties in plantation-grown Douglas fir in New Zealand. FRI, Genetics and Tree Improvement Report 59, NZ Forest Service, (unpublished). 41 pp.nStandards Association of Australia. (SAA) 1997. Mechanically Stress-Graded Timber. AS 1748-1997. 1997.nStandards Association of New Zealand (SAA) 1988. New Zealand Timber Grading Rules. NZS 3631:1988. 1988.nTimberfed News. 1996. The New Zealand Timber Federation Newsletter, October 1996.nWhiteside, I. D., and B. R. Manley. 1987. Radiata pine resource description by log grade specifications. Pages 27-38 in Proc. Conversion Planning Conference, 8-11 April 1986, Rotorua, FRI Bull. No. 128.nYoung, G. D., D. L. McConchie, and R. B. McKinley. 1991. Utilisation of a 25-year-old new crop radiata pine stand. Part 1: Wood Properties. NZ J. Forestry Sci. 21(2/3):217-227.n






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