UBC Theses and Dissertations
Wood quality of trembling aspen (Populus tremuloides Michx) and white spruce (Picea glauca (Moench) Voss) in the boreal mixedwood forest De Araujo, Francis Raiche
The boreal forest is the most widespread forest type in Canada, with a large percentage represented by mixedwood forests of white spruce (Picea glauca (Moench) Voss) and trembling aspen (Populus tremuloides Michx). It serves as not only a vast ecological reserve, but also as the supply source for forest-based industries. A better understanding of the interactions between the different species and their affects on productivity and wood quality traits helps create a more efficient industry that better utilizes the available resources, and concurrently preserves as much forest of ecological reserves and societal vistas. In this study, three sites composed of trembling aspen and white spruce, with varying compositions (one composed of mainly aspen, one of mainly spruce, and a mixed site with both species) were compared to determine how the presence of one species affects the growth and wood quality traits of the other. Four main wood quality traits were examined: wood density, microfibril angle (MFA), fibre traits (fibre length, fibre width and fibre coarseness) and cell wall chemistry. Along with site comparisons, social classes were determined for each site in an attempt to provide a more in-depth comparison across sites. Wood density showed very little variation among sites for both species, with only significant variations occurring between social classes. The aspen site showed statistically lower MFAs than the aspen from the mixed site, however, no differences were observed between the spruce from the mixed and spruce sites. Fibre length, width and coarseness were higher in the pure species sites for both trembling aspen and white spruce. In terms of cell wall composition, there were no differences in carbohydrate contents across sites for both species. Lignin content did vary, with the aspen site possessing higher lignin content than the mixed site, while for spruce the spruce site showed a lower lignin content. Overall, the use of social classes did not refine the characterization of site, producing similar results to those obtained when comparing trees by site, regardless of class.
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