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Exploring the use of average wood relative density of lodgepole pine sites as a predictor of MSR yield

https://library.fpinnovations.ca/en/permalink/fpipub5505
Author
Gonzalez, J.S.
Lum, Conroy
Munro, B.D.
Date
March 1993
Edition
37304
Material Type
Research report
Field
Sustainable Construction
Author
Gonzalez, J.S.
Lum, Conroy
Munro, B.D.
Date
March 1993
Edition
37304
Material Type
Research report
Physical Description
27 p.
Sector
Wood Products
Field
Sustainable Construction
Research Area
Advanced Wood Materials
Subject
Stresses
Pinus contorta
Pinus
Grading
Series Number
Forestry Canada No. 32
Contract no. 1212K029
W-1013
Location
Vancouver, British Columbia
Language
English
Abstract
The average relative density of lodgepole pine trees from five sites in three regions of interior B.C. was determined using lumber from a previous joinery-yield study. The use of relative density as a predictor of a site's potential for machine-stress-rated (MSR) lumber was explored by comparing the MSR lumber yields for a high and a low relative density site. There was a significant difference in the average relative density of the sites within a region and between regions. The average relative density ranged from 0.39 to 0.42 with a standard deviation of 0.02 to 0.03. Relative density generally declined with increasing stem height. Logs from the lowest point (first 3.7 meters from stump height of 30 cm) in the stem were higher in relative density than the logs from the upper part of the stem. The yield of 2400f-2.OE MSR grade lumber decreased with decreasing log density. There was a positive and significant correlation between relative density on one hand and stiffness (MOE) and MSR lumber yield on the other. MOE was influenced only partly but significantly by relative density. The overall MSR yield for the high and low relative density sites was significantly different. The site with the higher average relative density gave higher yield of MSR grade 2400f-2.OE and lower rejects (lower than 1650f-1.5E grade), while the site with the lower average relative density produced a negligible amount of the high MSR grade and higher rejects. Trees with high relative density were necessary for producing the 2400f-2.OE grade. Therefore, assessing the average relative density of a site should also quantify the relative density of trees at the upper tail of the relative density distribution.
Pinus contorta Dougl. var. latifolia - Density
Grading - Lumber - Stress, Mechanical
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