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紀要論文 / Departmental Bulletin Paper
To promote sustainable wood production based on plantation forestry using fast-growing tree species in Gabon, wood properties especially for anatomical characteristics, derived-wood properties related to pulp and paper quality, amounts of wood chemical components, and kraft pulp properties were investigated for Acacia sp. originated from plantation of A. mangium and A. auricuriformis in Gabon. Mean values of basic density, wood fiber length, wood fiber diameter, wood fiber wall thickness, vessel element length, vessel diameter, and vessel frequency were 0.50 g/cm3, 0.98 mm, 17.5 μm, 2.7 μm, 0.26 mm, 138 μm, and 8 vessels/mm2, respectively. Mean values were 0.45 for Runkel ratio, 0.69 for flexibility coefficient, 56.5 for slenderness ratio, 0.36 for Luce’s shape factor, 0.15 for coefficient of rigidity, and 156 × 103 μm3 for solid factor, respectively. Mean values of chemical and pulp properties, in heartwood were 6.0%, 16.4%, 7.2%, 0.4%, 23.5%, 74.9%, 59.5%, 54.8%, and 11.5 for hot-water extracts, 1% NaOH extracts, organic solvent extracts, ash, Klason lignin, holocellulose, α-cellulose, pulp yield, and kappa number, respectively. Obtained values of these characteristics in the present study were in the range of those reported in previous studies. Thus, it is considered that Acacia wood obtained from the plantation in Gabon can be used as raw material for pulp and paper production. In the present study, wood was classified into two types, core (up to 5 cm from pith) and outer wood in anatomical characteristics and derived-wood properties, and heartwood and sapwood in chemical and kraft pulp properties. As the results, these characteristics between core and outer wood, and heartwood and sapwood were almost the same, suggesting that effects of wood type (core or outer wood, and heartwood or sapwood) on pulp and paper quality might be limited on Acacia species grown in Gabon. Based on the results, it is concluded that raw materials of pulp and paper can be supplied from plantations of Acacia species in Gabon instead of natural forests.