FERIC compared three harvesting systems (full-tree, tree-length, and cut-to length) on a clay site in northwestern Québec. None of the systems limited rutting to below the acceptable target level; however, cut-to-length harvesting (using a three-machine system) showed slightly better results than the other two systems.
This report represents a breakdown of typical wood harvesting costs in eastern Canada using full-tree and cut-to-length systems. Representative costs were calculated on the basis of harvesting under favorable stand and site conditions, and the resultant costs were allocated to various accounting items (e.g. labor vs machine costs) and to each major work cycle phase. A sensitive analysis based on terrain and tree size variations was also conducted.
Harvesting with 33-m trail spacing was proposed by FERIC as a way to meet the quality criteria for single-tree selection in hardwood forests in Quebec's public forests. The approach is, however, applicable to any partial-cutting treatment in hardwood forests, and the method was studied in 16 operations in 2003-2004. The approach represents an acceptable compromise between protection of the residual stand and operating costs, as the productivity of the feller-bunchers using this method decreased only slightly as a result of increased travel. The operations that FERIC studied did not all meet the target quality criteria, but provided an adequate level of protection of residual stems. The method requires a certain degree of control to limit the felling of non-marked stems, and the use of evaluation criteria specially adapted to this method would facilitate its implementation.
Les auteurs définissent la qualité du bois en fonction de ses emplois, puis décrivent l'anatomie et la croissance du bois en regard de ses caractéristiques microscopiques et macroscopiques telles qu'observées en coupe transversale. Les exigences liées aux emplois sont énoncées selon les différentes classes de bois. Diverses caractéristiques déterminant la qualité du bois sont présentées et leurs conséquences pratiques pour la transformation du bois et les produits sont expliquées. Ces caractéristiques sont: la densité du bois, les variations de la densité, la répartition des bois juvénile et adulte, la proportion de duramen et d'aubier, la longueur des fibres, l'orientation des microfibrilles, le bois de compression, les noeuds, le grain ou la texture, le fil et les substances extractibles. Enfin, les auteurs traitent de la possibilité de modifier les paramètres de croissance de l'arbre et la qualité du bois grâce à un contrôle de la densité du peuplement. Les forestiers sont invités à prendre en considération les répercussions des travaux sylvicoles propres à chaque station.
The major defining characteristic of lumber cut from trees that have been infected with the mountain pine beetle is the extent of fungal bluestain in the sapwood. Forintek Canada Corp. scientists have previously observed that bluestained wood appears to have different dimensional stability characteristics than non-stained wood when subjected to repeated wetting and drying. Bluestained wood has also been reported to show increased permeability, which may make treatment with liquids such as wood preservatives easier. However, no data is available on how bluestained wood resulting from the beetle attack might affect. We therefore identified the need to generate data on the dimensional stability, checking, and permeability characteristics of bluestained wood compared with non-stained wood.
To examine dimensional stability, specimens of bluestained and non-stained 2 x 4 in. lumber were subjected to wetting/drying cycles. After 5 and 10 cycles, the amount of bow, crook, cupping, twist, and checking was measured. The permeability of the wood was also determined by weighing end-matched specimens before and after a 1-, 4-, and 24-hour dip or after a pressure treatment cycle with chromated copper arsenate preservative, and then calculating the uptake and preservative retention.
The results clearly show that when repeatedly wetted and dried, such as occurs in exterior end uses, bluestained beetle-killed wood is more dimensionally stable (less cupping and twist) and checks less than non-stained sapwood, but is more permeable to water. The stresses appear to be relieved by many micro-checks rather than fewer large checks. Overall, the improved dimensional stability should result in the lumber made from stained wood remaining straighter.
Increased permeability of the bluestained wood was confirmed by data showing enhanced chromated copper arsenate (CCA) uptake and penetration. One implication of the stained sapwood treating more readily than non-stained wood is that in batches of preservative-treated wood, the stained wood is liable to be overtreated or the non-stained wood undertreated. As anticipated, bluestain in the sapwood had no effect on the penetration of preservative into the heartwood, the most refractory part of the wood. Treatment with CCA also masked the bluestain by coloring it green.
The increased permeability probably also has implications for ease of air or kiln drying and possibly reduced degrade in the kiln.
Insects - Attack on trees
Stains - Fungal
Pinus contorta Dougl. var. latifolia - Defects
Preservatives - Permeability
Preservatives - Penetration
Pinus contorta Dougl. var. latifolia - Preservation
The major defining characteristic of lumber cut from trees that have been infected with the mountain pine beetle is the extent of fungal bluestain in the sapwood. It is reported that bluestained wood has shown increased permeability, and questions arose as to whether the application of an adhesive or a finish coating may be adversely affected. Laminating of wood is a key value-added process and one that is very dependent on the quality of the bond between two or more components. Bluestain is a common phenomenon in the secondary wood processing industry where finishing is part of the value-adding process. The finishing evaluations made in this study were intended to benefit these processors.
Pieces of bluestained and non-stained 2 x 4 in. lodgepole pine lumber were dried to a moisture content typically targeted by the furniture sector — i.e., much drier than lumber used for structural purposes. From this lumber, specially constructed edge-glued panels were made which exhibited bluestained to bluestained joints and non-stained to non-stained joints. This construction method provides bluestained and non-stained joints for the laminating tests, as well as providing a good representation of what will really happen in an industrial setting where bluestain most likely will not be separated from non-stain. Each panel was cut in half, with one half being used for the laminating tests and the other half for the finishing evaluations. The strength and durability of the glue lines were measured. Various finish coatings either used alone or in combinations with others were subjectively evaluated.
The laminating tests show that gluelines in lodgepole pine that contains beetle-transmitted bluestain were not significantly different in strength from gluelines in unstained wood when PVA and PRF adhesives are used. The durability of the bluestained beetle-killed wood gluelines easily met the requirements specified by the ASTM D1101 standard.
Where desired, the appearance of bluestained wood can be enhanced or highlighted by a simple standard clear furniture finish. Bluestain in parts of edge-glued panels can be masked if certain types of finishes are employed. The finishes that gave more consistently good masking results were those containing blue, red, and charcoal tints in the stain, toner, or glaze coatings. Increased permeability of the bluestain did not affect the adherence of any of the finishes.
While the finishing evaluations indicate the possibilities for finishing pine, whether it has bluestain or not, market research is recommended, using the best performing finishes on full-scale furniture pieces, to test consumer acceptance.