Canadian Forest Service Publications
Modeling flexural properties in white spruce (Picea glauca) and jack pine (Pinus banksiana) plantation trees. 2014. Vincent, M.; Duchesne, I. Can. J. For. Res. 44:82-91.
Issued by: Laurentian Forestry Centre
Catalog ID: 35344
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Mixed models combining random coefficient effect and covariance patterns were used to investigate mechanical property variations in jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) trees. Modulus of elasticity (MOE) and modulus of rupture (MOR) were measured by conducting three-point bending tests on small defect-free samples selected from different radial positions and at a height of 2.5 m above ground within the stems. The objective of the paper was to build statistical predictive models describing the radial variations in stems for wood mechanical properties using easily measurable explanatory variables that are typically available in the wood manufacturing industry: distance from pith, tree height and diameter, and spacing. The explanatory variables integrated into the models explained MOE adequately, whereas MOR appeared harder to predict with only these variables and at this resolution. For white spruce, the best mixed-effects models explained 80% and 61% of the variation in MOE and MOR, respectively. For jack pine, it was 51% and 33% for the same response variables. These results are a step toward models that could be used in sawing simulation software designed to estimate the internal properties of sawlogs and, as a result, better predict lumber and pulp chip quality.
Plain Language Summary
Several factors, including species, spacing between trees and soil type, have an impact on the quality of trees grown in plantations for saw timber. Knowing the quality of the wood grown in plantations is a key piece of business information for wood processing firms.
The objective of this study, which looks at white spruce and jack pine, which are some of the species of trees most frequently planted in Quebec, was to construct a statistical model to be used to predict variations in the mechanical properties of wood inside stems, based on easily measurable data that are generally available to forest stakeholders and those who process wood: distance from the pith, tree height and diameter, and spacing between trees in the plantation.
Two mechanical properties were studied: the elasticity module and the rupture module. The elasticity module is a measurement of wood rigidity when the wood is placed under increasingly constrained conditions without causing the wood to be permanently deformed. The rupture module is a measurement of the maximum force that a piece of wood can withstand before breaking.
The developed models explained the elasticity module more effectively than they did the rupture module, and better results were obtained for white spruce than for jack pine. These models will be used to develop sawing simulation software programs that may help the industry to better assess the quality of saw timber and wood chips produced.