IMPACT OF SPACING ON WIDTH AND BASAL AREA OF JUVENILE AND MATURE WOODIN PICEA-MARIANA AND PICEA-GLAUCA

Ten trees of Picea mariana (Mill.) B.S.P. and Picea glauca (Moench.) V oss grown at each of three spacings - 1.8 m x 1.8 m, 2.7 m x 2.7 m, an d 3.6 m x 3.6 m - were randomly selected for study of impact of spacin g on juvenile and mature wood width. The plantation located in northwe stern Ontario was established in 1951 and was sampled in 1989. Tree di ameter and tree basal area at breast height, juvenile and mature wood width, both as a ring count and as a linear measurement, basal area an d its percentage of juvenile and mature wood, and growth rate in juven ile and mature wood were measured. Data were analyzed with an F-test a nd the Student-Newman-Keuls test. Correlation coefficients among vario us variables were also calculated. It was found that impact of spacing on wood properties is more pronounced in Picea glauca, which is consi dered a fast-growing tree in comparison to Picea mariana, than in P. m ariana. The number of growth rings in juvenile wood of P. mariana and P. glauca were counted as 14 to 16 growth rings and 12 to 16 growth ri ngs, respectively, depending upon the spacing. Statistically, there ar e no differences in juvenile wood growth rings of P. mariana at variou s spacings, but analysis shows more growth rings in P. glauca juvenile wood at the widest plantation spacing. A tendency of increasing juven ile wood width with increasing spacing was observed. The percentage of juvenile wood basal area was 37% to 62% in P. glauca. A positive rela tionship between the percentage of juvenile wood basal area and the pl antation spacing was found in P. glauca but not in P. mariana. In P. m ariana, the percentage of juvenile wood basal area was 50% and was ind ependent of spacing. Growth rate of juvenile wood in both species show s a positive relation with the spacing. The growth rate in juvenile wo od is two to three times higher than that of mature wood. The impact o f spacing on the properties of mature wood is similar to that of juven ile wood, except that mature wood width in P. mariana shows no differe nce among spacings. It is concluded that plantation spacing has variou s degrees of impact on juvenile and mature width, and its impact is al so species-specific.