Log quality characteristics of mountain pine beetle killed lodgepole pine trees from southern interior British Columbia for board processing .

摘要

The mountain pine beetle (MPB) (Dendroctonus ponderosae Hopkins) epidemic has ravaged lodgepole pine (Pinus contorta var. latifolia) forests throughout British Columbia (BC). The research focussed on the effects of three stages of MPB trees, green, red, and grey attack from southern interior BC on the MPB-induced variables of log moisture content (MC), blue stain, and checking and how these relate to log quality from an end product perspective. The objectives were to determine if: 1) the percentage of blue stain calculated from the log end surface at diameter breast height (DBH) correlates to the percentage of blue stained boards; 2) the quantity and size of checks present in a disk removed at DBH correlates to the percentage of checked boards; 3) the sapwood moisture content from a cross sectional disc at DBH correlates to the percentage of MPB-induced degrades (checking, wood borers, and decay fungi). Three sections of each MPB log (bottom, middle, and top), were examined for the MPB-induced degrades blue stain, checking, and the losses due to wood borers and decay fungi.;Forest product mills can use these results for predicting the log quality characteristics of MPB trees for board processing. Woodlands departments and especially timber purchasers are always concerned about predicting the value of MPB trees and these results may be useful to the forest industry to determine if a predominantly lodgepole pine stand of MPB trees can be profitable. As shown in this study and others, losses due to checking and blue stain are the primary reasons for decreased MPB grade recovery and value.;The results support the findings of previous MPB research where reduced moisture content, blue stain, and checking significantly reduce log quality. However, this study is unique since it relates these findings to the effects that they have on the board products. The percentage of blue stain from a disc cut at DBH is correlated to the percentage of blue stained boards from that tree for green, red, and grey attack. As blue stain increases in the disc cut at DBH by attack stage, the amount of blue stained boards also increases by attack stage. When the check depth is >3 cm and the check depth to width ratio in a disk cut at DBH is >4, there is a positive correlation to the percentage of checked boards for that tree. If the check depth to width ratio is less, these shallow checks are removed by the canter chipping heads during primary breakdown. As MC decreases below the fibre saturation point, there is a linear relationship between MC and MPB-induced board degrades (checking, grubholes, and pinholes).