KRAFT PULP FROM NORWAY SPRUCE (PICEA ABIES) Thinned at 30 Years Age, 2002 Kraft Pulp Yield Symposium

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This study illustrates the influence of growth rate on the kraft pulp properties of 30 to 35-year-old Norway spruce (Picea abies) removed during a thinning. Wood from the fastest growing stand had a mean annual ring width of 5.6 mm and a mean basic density of 323 kg/m³, whereas corresponding values for the slowest growing stand were 2,9 mm and 384 kg/m³, respectively. The remaining stands had intermediate ring widths and basic densities. Process and pulp characteristics were found to be similar for wood from stands with a mean annual ring width between 3 mm and 4mm and a mean basic density ranging from 350 to 400 kg/m³. Wood from the stand with a mean ring width exceeding 5 mm and a mean basic density of 323 kg/m³ had shorter fibers and longer cooking time to reach a certain kappa number, compared with wood from the other stands. Furthermore, this wood consumed more chemicals and yielded l-2 percentage units less pulp. The volume of wood needed to produce, 1 ton of pulp was 6.4m for the fastest growing trees and 5.2 m³ for the slowest growing ones.