Influence of regeneration method on juvenile jack pine clear wood static bending properties and specific gravity.

摘要

The effects of regeneration method on three wood properties of jack pine, along different vertical positions, grown in northwestern Ontario were evaluated. A multi-staged nested sampling design was used to randomly select 12 trees, approximately 25 years of age, from four stands that were aerial seeded, Bracke seeded, planted and post fire naturally regenerated. Within each tree, small clear wood samples (2 cm x 2 cm x 30 cm) were obtained from three vertical positions: 1 m, 2 m and 4 m, for the determination of static bending properties - modulus of elasticity (MOE) and modulus of rupture (MOR) - and specific gravity. Data analysis revealed that all three wood properties, MOE, MOR and specific gravity were not significantly different statistically (alpha ≤ 0.05) between regeneration methods. Further analysis into the influence of vertical positions revealed that MOE was not significantly different with height for all regeneration methods. In contrast, MOR was found to significantly vary between the bottom and top positions for the aerial seeded and naturally regenerated stands. With respect to specific gravity, a significant difference in vertical position was evident between the bottom and top bolts for the aerial seeded, Bracke seeded and natural stands. These findings have revealed that wood properties of juvenile jack pine are quite variable no matter what regeneration method is implemented. Moreover, in the future there may be potential in dividing jack pine logs along the stem for various uses based on regeneration method.;The relationship between MOR and specific gravity, and MOE and specific gravity were investigated for all vertical positions and for each regeneration method. Linear and curvilinear equations were used to compare the variation in mechanical properties as a function of specific gravity. In all cases, a significant (alpha ≤ 0.05) positive relationship existed between specific gravity and MOR or MOE. The relationship between MOR and specific gravity is equally well explained by linear and curvilinear equations, whereas the relationship between MOE and specific gravity is better explained by a linear equation than by a curvilinear equation.;Keywords. jack pine, juvenile wood, modulus of elasticity, modulus of rupture, regeneration methods, specific gravity, vertical position.