Wood and bark fiber characteristics of Acacia melanoxylon and comparison to Eucalyptus globules

Abstract

Wood and bark fi bers of Acacia melanoxylon were characterizedandcompared to Eucalyptus globulus which is a major quality source of pulp fi bers. In 20 trees from four sites, fi ber length and wall thickness were measured at 5, 35 and 65% of total tree height and at 10, 30, 50, 70 and 90% of the distance from pith. Maceration were prepared in a 1:1 glacial acetic acid:hydrogen peroxide solution. Wood and bark fi ber length varied between 0.90 - 0.96 mm and 1.33 - 1.59 mm respectively. The cell wall thickness varied between 3.45 - 3.89 μm in wood and 5.01 - 5.40 μm in bark. Wood and bark fi ber length decreased from the bottom to the top of the tree and cell wall thickness had no specifi c pattern for axial variation. Fiber length and wall thickness increased from the pith to the bark, but the wall thickness increased slightly with some fl uctuations. In Acacia melanoxylon signifi cant site differences were found in relation to bark fi ber length and to wood wall thickness. The fi bers of Acacia melanoxylon were similar to those of Eucalyptus globulus but the wood fi bers were thinner and the bark fi bers thicker. The radial variation was similar in both species. Inwoodof Eucalyptus globulus,fi ber wall thickness increases from the base to the middle of tree height and decreases to the top; in the bark decreases from the base to the top. In Eucalyptus globulusfi bers bark are higher in the top.