Impact of Initial Spacing on Plantation Black Spruce Lumber Grade Yield, Bending Properties, and MSR Yield


  • S. Y. Zhang
  • Gilles Chauret
  • Haiqing Q. Ren
  • Richard Desjardins


For decades, initial spacing of 2 m X 2 m has been used for black spruce (Picea mariana) reforestation in eastern Canada. In recent years, however, wider spacings for black spruce are being advocated to reduce establishment costs and accelerate tree growth. Wider spacings will affect not only return on investment but also the quality of products from the plantations, both of which are critical to the success of reforestation programs. As part of a multidisciplinary project, this study evaluated and quantified the impact of initial spacing on lumber grade yield, bending properties, and MSR yield in this species. Furthermore, visual grades of the plantation-grown lumber were compared for their bending properties and their compliance to the current grade requirements for bending stiffness. A total of 139 sample trees were collected from 4 different spacings (3,086, 2,500, 2,066, 1,372 trees/ha) in a 48-year-old initial spacing trial, and 849 pieces of 2-in.-thick lumber from the 4 spacings were graded visually and tested for bending strength and stiffness.

With decreasing initial stand density from 3,086 to 2,066 trees/ha, branch diameter showed a steady increase. However, the 3 higher stand densities (3,086, 2,500, and 2,066 trees/ha) had a comparable Select Structural (SS) grade yield thanks to the relatively small branches in this species. Lumber strength and stiffness in those 3 spacings were also quite comparable. When the initial stand density was further reduced to 1,372 tree/ha, however, a remarkable decrease in the SS grade yield due to knots occurred, and lumber strength and stiffness also decreased significantly. The real concern occurred when the plantation-grown lumber was compared to that from natural stands currently being processed in eastern Canada. On average, the plantation-grown black spruce lumber stiffness was 28.9% lower than that of lumber from the natural stands. As a result, a high percentage of the plantation-grown lumber did not meet the bending design values. However, the percentage of the compliance to the design values tended to increase with increasing initial stand density. This article discusses the possible causes for the significantly lower bending properties of the plantation-grown lumber, and potential solutions for increasing lumber properties and the percentage of the compliance.


American Society of Testing and Materials (ASTM). 1997. Annual Book of ASTM Standards, Vol. 04.10 Wood. American Society of Testing and Materials, Philadelphia, PA. 676 pp.nBallard, L. A., and J. N. Long. 1988. Influence of stand density on log quality of lodgepole pine. Can. J. For. Res. 18:911-916.nBao, F. C., Z. H. Jiang, X. M. Jiang, X. X. Lu, X. Q. Luo, and S. Y. Zhang. 2001. Differences in wood properties between juvenile wood and mature wood in 10 species grown in China. Wood Sci. Technol. 35:363-375.nBarrett, J. D., and R. M. Kellogg. 1991. Bending strength and stiffness of second-growth Douglas-fir dimension lumber. Forest Prod. J. 41(10):35-43.nBarrett, J. D., and W. Lau. 1994. Canadian lumber properties. Canadian Wood Council, Ottawa, Ontario. 346 pp.nBell, F. W., W. D. Baker, and R. Vassov. 1990. Influence of initial spacing on jack pine wood yield and quality. NWOFTDU Technical Report #10, Thunder Bay, Ontario. 27 pp.nBendtsen, B. A., P. Plantiga, and T. A. Snellgrove. 1988. The influence of juvenile wood on the mechanical properties of 2 X 4 cut from Douglas-fir plantations. Pages 226-240 in Proc. International Conference on Timber Engineering, Seattle, WA.nBiblis, E. J. 1990. Properties and grade yield of lumber from a 27-year-old slash pine plantation. Forest Prod. J. 40(3):21-24.nBiblis, E. J., R. Brinker, H. F. Carino, and C. W. McKee. 1993. Effect of stand age on flexural properties and grade compliance of lumber from loblolly pine plantation timber. Forest Prod. J. 43(2):23-28.nBier, H. 1986. Log quality and the strength and stiffness of structural timber. N.Z.J. For. Sci. 16:176-186.nButterfield, B. G. 1997. Microfibril angle in wood. Proc. IAWA/IUFRO International Workshop on the Significance of Microfibril Angle to Wood Quality. Westport, New Zealand. 410 pp.nCave, I. D., and J. C. F. Walker. 1994. Stiffness of wood in fast-grown plantation softwoods: The influence of microfibril angle. Forest Prod. J. 44(5):43-48.nCCFM. 1996. Forest regeneration in Canada 1975-1992. Canadian Council of Forest Ministers, Ottawa, Ontario. 41 pp.nDaniel, T. W., J. A. Helms, and F. S. Baker. 1979. Principles of silviculture. McGraw-Hill Book Company, New York, NY.nDeBell, J. D., J. C. Tappeiner, and R. L. Krahmer. 1994. Branch diameter of western hemlock: Effects of pre-commercial thinning and implications for log grades. Western J. Appl. Forestry 9(3):88-90.nEvert, F. 1971. Spacing studies: A review. Information Report FMR-X-37, Can. For. Serv., Sault Ste-Marie, Ontario.nGrant, D. J., A. Anton, and P. Lind. 1984. Bending strength, stiffness, and stress-grade of structural Pinus radiate: Effect of knots and timber density. N.Z.J. For. Sci. 14:331-348.nKellogg, R. M. 1989. Second growth Douglas-fir: Its management and conversion for value. Special Pub. SP-32, Forintek Canada Corp., Vancouver, BC. 173 pp.nKennedy, R. W. 1995. Coniferous wood quality in the future: Concerns and strategies. Wood Sci. Technol. 29: 321-338.nKennedy, R. W., and W. G. Warren. 1969. Within-tree variation in physical and chemical properties of Douglas-fir. FAO Second World Counsul. on For. Tree Breeding. FO-FTB-69-4/4. 20 pp.nKoponen, S. 1997. Effect of wood micro-structure on mechanical and moisture physical properties. Pages 348-366 in B. G. Butterfield, ed. Microfibril angle in wood. Proc. IAWA/IUFRO International Workshop on the Significance of Microfibril Angle to Wood Quality, Westport, New Zealand.nKretschmann, D. E., and B. A. Bendtsen. 1992. Ultimate tensile stress and modulus of elasticity of fast-grown plantation loblolly pine lumber. Wood Fiber Sci. 24(2):189-203.nMacPeak, M. D., L. F. Burkart, and D. Weldon. 1990. Compression of grades, yields, and mechanical properties of lumber produced from young, fast-grown and old, slow-grown plantation slash pine. Forest Prod. J. 40(1):1-14.nMattsson, S., S. Y. Zhang, R. Evans, U. Bergsten, and E. Kubin. 2002. Effects of site type, soil scarification method, and tree type on wood anatomical, physical, and mechanical properties in Scots pine (Pinus sylvestris). (submitted).nMcClain, K. M., D. M. Morris, S. C. Hills, and L. J. Busss. 1994. The effect of initial spacing on growth and crown development for planted northern conifers: 37-year results. For. Chronicle 70:174-182.nMiddleton, G. R., and B. D. Munro. 1989. Log and lumber yields. Pages 66-74 in R. M. Kellogg, ed. Second growth Douglas-fir: Its management and conversion for value. Special Pub. SP-32, Forintek Canada Corp., Vancouver, BC.nMullins, E. J., and T. S. McKnight. 1981. Canadian woods: Their properties and uses. Univ. Toronto Press, Toronto, Ontario. 389 pp.nNLGA. 1996. Standard grading rules for Canadian lumber. National Lumber Grades Authority, Vancouver, BC.nNLGA. 1997. Special products standard for machine graded lumber SPS 2-97. National Lumber Grades Authority, Vancouver, BC.nRowe, J. S. 1972. Forest regions of Canada. Can. For. Serv., Pub. No. 1300, Ottawa, Ontario. 172 pp.nSjolte-Jorgenstern, J. 1967. The influence of spacing on the growth and development of coniferous plantations. Int. Rev. For. Res. 2:43-93.nThrower, J. S. 1986. Estimating site quality from early height growth of white spruce and red pine plantations in the Thunder Bay area. M.Sc.F. Thesis, School of Forestry, Lakehead Univ., Thunder Bay, Ontario.nTsehaye, A., A. H. Buchanan, R. Meder, R. H. Newman, and J. C. F. Walker. 1997. Microfibril angle: Determining wood stiffness in radiata pine. Pages 323-336 in B. G. Butterfield, ed. Microfibril angle in wood. Proc. IAWA/IUFRO International Workshop on the Significance of Microfibril Angle to Wood Quality, Westport, New Zealand.nYang, K. C. 1994. Impact of spacing on width and basal area of juvenile and mature wood in Picea mariana and Picea glauca.Wood Fiber Sci. 26(4):479-488.nYang, K. C., and G. Hazenberg. 1992. Impact of spacing on sapwood and heartwood in Picea mariana (Mill.) B.S.P. and Picea glauca (Moench.) Voss. Wood Fiber Sci. 24(3):330-336.nYang, K. C., and G. Hazenberg. 1994. Impact of spacing on tracheid length, relative density, and growth rate of juvenile wood and mature wood in Picea mariana.Can. J. For. Res. 24(5):996-1007.nZhang, S. Y. 1996. Effect of growth rate on wood specific gravity and mechanical properties in individual species from distinct wood categories. Wood Sci. Technol. 29(6):451-465.nZhang, S. Y., and Y. Zhong. 1992. Structure-property relationship of wood in East-Liaoning oak. Wood Sci. Technol. 26:139-149.nZhang, S. Y., and G. Chauret. 2001. Impact of initial spacing on tree and wood characteristics, product quality, and value recovery in black spruce. Canadian Forest Service No. 35, Forintek Canada Corp., Sainte-Foy, Quebec. 42 pp.nZhang, S. Y., Y. Corneau, and G. Chauret. 1998. Impact of precommercial thinning on tree and wood characteristics, product quality, and value in balsam fir. Canadian Forest Service No. 39, Forintek Canada Corp., Sainte-Foy, Quebec. 74 pp.nZhou, H., and I. Smith. 1991. Factors influencing bending properties of white spruce lumber. Wood Fiber Sci. 23(4):483-500.nZobel, B. J., and J. R. Sprague. 1998. Juvenile wood in forest trees. Springer-Verlag, Berlin. 300 pp.n






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