Moisture distribution in stems of Acacia mangium, A. auriculiformis and hybrid Acacia trees

Distribution of the moisture content across stem wood at breast height in Acacia mangium, A. auriculiformis, and hybrid Acacia trees grown in 3 Asian countries was evaluated. Moisture contents of the stems of A; mangium and hybrid Acacia were extremely high not only in sapwood but also in heartwood in most cases. Highest moisture content found in the inner heartwood was 253% for both A. mangium and hybrid Acacia. In sapwood, the moisture contents were 149% and 154%, respectively. Most trees of these 2 species had "wet-heartwood" which refers to the higher moisture content of heartwood compared to the surrounding sapwood. Stem wood of A. auriculiformis generally showed a slightly lower moisture content than that of A. mangium and hybrid Acacia. However, the highest moisture content found in the inner heartwood was 146% in A. auriculiformis. The large amount of water in stem wood, especially in the heartwood of these Acacia species hampers drying which is necessary for the production of sawn timber and processing to panel products. Several factors such as characteristics of clones or provenance of seeds, and amount of precipitation at plantation sites could be involved in the large fluctuations in the moisture contents of the stems of these Acacia trees. Further studies should be carried out to determine the conditions necessary for lowering the moisture content of stem wood in order to optimize the utilization of these plantation species.