Abstract
This study has quantified basic wood density and various types of wood shrinkage in relation to initial spacing (or initial planting density) and tree growth based on a 48-year-old black spruce (Picea mariana) spacing trial in eastern Canada. A total of 139 sample trees were collected from four initial spacings (3086, 2500, 2066, 1372 trees/ha) for this study. Analyses of variance (ANOVA) show that initial spacing is the most important parameter affecting wood density significantly, followed by tree diameter at breast height (DBH) class. With increasing spacing, wood density, radial and volumetric shrinkage tend to decrease, whereas longitudinal shrinkage tends to increase gradually. The largest spacing has the lowest wood density, the smallest transverse shrinkage and the largest longitudinal shrinkage. Path analysis indicates that wood density is the most important parameter affecting transverse shrinkage, followed by the distance from the pith. Furthermore, much of the variation of the transverse shrinkage with wood density may be due to the initial spacing and tree DBH class. Path analysis also reveals that longitudinal shrinkage is mainly related to log height and tree DBH class. With increasing log height, longitudinal shrinkage tends to increase, and transverse shrinkage tends to decrease. With increasing DBH class, the trees tend to have an increasing longitudinal shrinkage and a decreasing transverse shrinkage. Overall, this study suggests that a large increase in the initial spacing (e.g., 1372 trees/ha) might lead to a significant reduction in both wood density and transverse shrinkage, and a significant increase in longitudinal shrinkage in black spruce.
Highlights
Black spruce (Picea mariana [Mill.] B.S.P.) is the most important reforestation and commercial species in eastern Canada
As part of this project, this study was intended to quantify the impacts of initial stand density and tree growth on wood density and wood shrinkage, two wood quality attributes of high importance to solid wood products
The analysis of variance (ANOVA) results (Table 2) show that initial spacing has a significant effect on basic wood density at the 0.01 level
Summary
Black spruce (Picea mariana [Mill.] B.S.P.) is the most important reforestation and commercial species in eastern Canada. A multidisciplinary project [9] was undertaken to quantify the impacts of initial stand density along the wood value chain including major wood and product properties in black spruce based on one of the oldest and well-documented initial spacing trials in eastern Canada. As part of this project, this study was intended to quantify the impacts of initial stand density and tree growth on wood density and wood shrinkage, two wood quality attributes of high importance to solid wood products
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