Influence of wood basic density on acacia melanoxylon kraft process

摘要

Wood density is a complex physical property related to the anatomical structure and the chemical composition ofwood and one of the most important wood quality factors. Sampling was based on a total of 20 trees from foursites in Portugal that were harvested at a sawmill diameter class of 40 cm and wood discs taken at differentheight levels from the base to the top of the tree.The mean basic density of the Acacia melanoxylon trees measured at 5% height level (near breast height level)was 516 kg/m3 with a 34 kg/m3 standard deviation. The within-tree axial variation of density was of smallmagnitude, but showing higher values at the stem base and top. Site had no influence on the basic density of thewood. Overall the between tree variation of density was small possibly linked to the narrow genetic diversity ofthis introduced exotic species. In the Kraft process we can observe variability between stands and an increase ofthe pulp yield, and fiber width and length with the higher level in the tree. The wood basic density is wellcorrelated with the ISO brightness and well correlated in inverse order with the pulp Yield and fiber width andlength. The kappa number don’t present a great variation with the wood basic density.