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Fresh-wood bending: linking the mechanical and growth properties of a Norway spruce stem

  • Lundström, Tor Swiss Federal Institute for Snow and Avalanche Research, Davos Dorf, Switzerland - Department of Geosciences, Laboratory of Dendrogeomorphology, University of Fribourg, Switzerland
  • Heiz, Urs Swiss Federal Institute for Snow and Avalanche Research, Davos Dorf, Switzerland
  • Stoffel, Markus Department of Geosciences, Laboratory of Dendrogeomorphology, University of Fribourg, Switzerland
  • Stöckli, Veronika Swiss Federal Institute for Snow and Avalanche Research, Davos Dorf, Switzerland
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    2007
Published in:
  • Tree Physiology. - 2007, vol. 27, p. 1229-1241
annual ring width, bending mechanics, bulk density, heartwood, knottiness, latewood, sapwood, stem growth, water content
English To provide data and methods for analyzing stem mechanics, we investigated bending, density and growth characteristics of 207 specimens of fresh wood from different heights and radial positions of the stem of one mature Norway spruce (Picea abies L. Karst.) tree. From the shape of each stress–strain curve, which was calculated from bending tests that accounted for shear deformation, we determined the modulus of elasticity (MOE), the modulus of rupture (MOR), the completeness of the material, an idealized stress–strain curve and the work involved in bending. In general, all mechanical properties increased with distance from the pith, with values in the ranges of 5.7–18 GPa for MOE, 23–90 MPa for MOR and 370–630 and 430–1100 kg m⁻³ for dry and fresh wood densities, respectively. The first three properties generally decreased with stem height, whereas fresh wood density increased. Multiple regression equations were calculated, relating MOR, MOE and dry wood density to growth properties. We applied these equations to the growth of the entire stem and considered the annual rings as superimposed cylindrical shells, resulting in stem- section values of MOE, MOR and dry and fresh densities as a function of stem height and cambial age. The standing tree exhibits an inner stem structure that is well designed for bending, especially at a mature stage.
Faculty
Faculté des sciences et de médecine
Department
Département de Géosciences
Language
  • English
Classification
Biology
License
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Persistent URL
https://folia.unifr.ch/unifr/documents/300530
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