Juvenile wood effect in red alder (Alnus rubra) and Oregon white oak (Quercus garryana)
Abstract
The objective of this study was to investigate the influence of juvenile wood on the mechanical and physical properties of red alder and Oregon white oak. Tree growth in the first 10-20 years, usually referred to as juvenile wood, often influences wood quality by adversely affecting strength properties. Strength can be reduced up to 50 percent by the presence of juvenile wood. More knowledge of juvenile/mature wood properties will provide practical information for silviculturists and processors of red alder and Oregon white oak, leading to a more appropriate usage of these species. Additionally, further information was obtained for the juvenile/mature wood property based demarcations in a diffuse-porous and ring-porous species. Six trees each of red alder and Oregon white oak were used in this investigation and a collaborative anatomical study by Oregon State University (OSU). The three-point-bending test mini-specimens (0.625 cm wide, 0.625 cm deep, and 10.16 cm long) were taken from a pith-centered, radially-oriented slab in the green condition. Sample material was taken at breast height and below the first major branch for height comparison. Measured variables for the Purdue study were modulus of elasticity, modulus of rupture, specific gravity, and apparent work, with the OSU anatomical variables of fiber length and vessel diameter incorporated for correlation. Modulus of elasticity in red alder was found to have a mean join point (end of juvenility) of approximately 16 years and 10 years for the bottom and the top sections, respectively. The variability of modulus of rupture, specific gravity, and apparent work property values over time rendered them unsuitable for indicating a juvenile-mature wood join point. Fiber length was found to be a good predictor of the modulus of elasticity for red alder. No mechanical or physical properties of Oregon white oak were found to be suitable for determination of a juvenile-mature wood join point.
Degree
Ph.D.
Advisors
Senft, Purdue University.
Subject Area
Forestry|Wood|Technology
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