Impact of Spacing on Juvenile Wood and Mature Wood Properties of White Spruce (Picea glauca)
摘要
The impact of spacing on the growth rate, relative density, and tracheid length of juvenile and mature wood was evaluated. Ten plantation-grown white spruce (Picea glauca Moench. Voss) trees 38 years old grown at each of 3 spacings, i.e., 1.8×1.8 m, 2.7×2.7 m, and 3.6×3.6 m at Stanley, 30km west of Thunder Bay, Ontario were randomly selected for this study. Samples consisting of 12-mm-diameter increment cores were extracted at breast height from the south aspect of each tree. A contrast test was applied statistically to test the difference between spacings. Boundaries of juvenile and mature wood were demarcated with an earlywood tracheid length variation method. The juvenile-mature transition period of P. glauca ranged from 8 to 20 years. For all 3 plantation spacings, the growth rate in juvenile wood was greater than that of mature wood. In contrast, the mean earlywood tracheid length in juvenile wood, ranged from 1.8 to 2.0 mm which is shorter than those of mature wood which ranged from 2.9 to 3.0 mm. The relative densities (acetone extractive free) of juvenile and mature wood were found to be very similar for each spacing. The highest mean relative densities which occurred at the narrowest spacing were 0.38 to 0.37 for juvenile and mature wood, respectively. The mean relative densities of trees at the 2 wider spacings ranged from 0.33 to 0.35. Results of the contrast test indicated that there was no statistically significant impact of spacing on tracheid length, except in juvenile wood at the widest spacing which has long tracheids. However, arithmetically, a trend of increasing tracheid length with increasing spacing was discerned. This observation does not agree with most in the reports literature. Further studies are needed to clarify these contradictory results.