Variation in Trembling Aspen and White Spruce Wood Quality Grown in Mixed and Single Species Stands in the Boreal Mixedwood Forest

Abstract

Abstract:The Canadian boreal forest is largely represented by mixed wood forests of white spruce (Picea glauca (Moench) Voss) and trembling aspen (Populus tremuloides Michx). In this study, a total of 300 trees originating from three sites composed of trembling aspen and white spruce with varying compositions were investigated for wood quality traits: one site was composed mainly of aspen, one mainly of spruce and a third was a mixed site. Four wood quality traits were examined: wood density, microfibril angle (MFA), fibre characteristics, and cell wall chemistry. Social classes were also determined for each site in an attempt to provide a more in-depth comparison. Wood density showed little variation among sites for both species, with only significant differences occurring between social classes. The aspen site showed statistically lower MFAs than the aspen from the mixed site, however, no differences were observed when comparing spruce. Fibre characteristics were higher in the pure species sites for both species. There were no differences in carbohydrate contents across sites, while lignin content varied. Overall, the use of social classes did not refine the characterization of sites.

Evaluating the impact of stand composition and competition on white spruce and aspen wood attributes in the boreal mixedwood

“…Previous study has shown that there was no effect of mixed vs pure competition having an effect on wood density (De Araujo et al 2015)…”

“…Within mixed forest plantations in Eastern Quebec, distance independent indices have successfully quantified the competition effect on basal area increment growth in planted white spruce, while distance-independent indices worked best for ingrown or non-planted species (Bérubé-Deschênes 2017). In an analysis of permanent sample plots that included pure and mixed stands of aspen and white spruce of varying age in Central Alberta, wood density and carbohydrate content was found to be consistent across sites, while MFA was lower within aspen sampled in pure stands and fibre characteristics were higher in the pure site for both species (De Araujo et al 2015). Previous studies have been limited due to sampling uneven age stands with inconsistent measures of treatment density.…”

“…Longer fibres have been reported for mixed white spruce and aspen sites compared to pure stands (De Araujo et al 2015).…”

“…Lower Coarseness means higher tear strength, greater bonding area, and more fibres per tonne of pulp, which are important to papermaking (Watson and Bradley 2009) Higher coarseness has been reported for mixed white spruce and aspen sites compared to pure stands (De Araujo et al 2015).…”

“…Fibre morphology and cell wall structure directly influences fibre flexibility, plasticity and resistance to processing Longer fibres have been reported for mixed white spruce and aspen sites compared to pure stands (De Araujo et al 2015).…”