INITIAL MOISTURE-CONTENT, DENSITY AND SHRINKAGE OF BINUANG (OCTOMELESSUMATRANA) FROM SABAH

Introduction Binuang (Octomeles sumatrana Mig., Datiscaceae) is a fast growing tree of the Indo-Malesian region with long, straight and cyli ndrical boles. Although Binuang is site selective and mainly stocks in riverine alluvial forests (Whitmore 1990), it is considered a potenti al plantation tree (Pratiwi and Alrasjid 1988). Some plantation trials were established in the 70's (Shim 1973) and new trials are currently conducted. In view of the renewed interest in this species, the varia bility of the initial moisture content, the wood density and the shrin kage values of Binuang grown in Sabah was investigated. Materials and Methods The height of the 10 sample trees varied between 30 and 34 m a nd their diameter at breast height between 41 and 50 cm. Standard test samples for the determination of density and shrinkage values were pr epared from breast height as well as from approximately 50% and 80% he ight of the branch free bole. Samples for the determination of the ini tial moisture content were taken at breast height and at 30%, 60% and 90% of the height of the branch free bole. The tests followed standard procedures. Results The initial moisture content of Binuang varies fr om 96% to 265%. At breast height, 30% and 60% of the tree height it in creases from the periphery (105%-125%) to the centre of the stem (123% -265%). This increase is more pronounced at breast height and 30% heig ht of the branchfree bole than at 60% height and it is not present at 90% of the bole height (Fig. I). In the periphery of the stem there ar e only minor differences in moisture content between different height levels. In the centre of the stem, however, the moisture content decre ases with increasing tree height. All trees studied showed a similar p attern.In standard climate Binuang has a moisture content of 14%. The wood density at 14% moisture content ranges from 0.17-0.45 g/cm(3). Th e average density of the different trees varied from 0.26-0.33 g/cm(3) . The trees show an insignificant decrease of wood density with tree h eight and a slight increase from the centre of the stem towards the pe riphery. These changes, however, are small and do not influence the po ssible utilisation of Binuang timber. The average tangential shrinkage values are 6.5% (green to dry) and 2.8% (green to 14% moisture conten t). The radial shrinkage values are 3.5% (green to dry) and 1.5% (gree n to 14% moisture content); the axial shrinkage values are 0.5% (green to dry) and 0.2% (green to 14% moisture content). With increasing tre e height the shrinkage values decrease significantly. The tangential v alues (green to 14% moisture content/green to dry) drop from 3.4%/7.6% at breast height to 1.9%/5.1% at 80% bole height. Over the same dista nce, the radial values drop from 1.9%/4.0% to 1.2%/3.1%. There is no s ignificant difference between the centre and the periphery of a stem. Data on the variability of the initial moisture content within individ uals of Binuang were not available so far. The observed values for den sity and shrinkage do not lie outside the range of values reported in literature (e.g. Lemmens et al. 1995).