Determination of juvenile and mature transition ring for fast growing sengon and jabon wood

摘要

Timber as an important forest resource in the tropics has been processed to wood products in large quantity to fulfill an increasing need of both local and international consumers. To satisfy the increasing demand for the wood products, much of the timber has been supplied from fast-growing tree species grown on managed plantations (community forest, industrial plantation forest). The fast-growing wood species have been harvested in short age rotations and could contain higher proportions of juvenile wood. This research article discusses the occurrence and characteristics of juvenility in sengon (Paraserianthes falcataria) and jabon (Anthocephalus cadamba) woods based on density, bending strength (modulus of rupture (MOR), modulus of elasticity (MOE)), fiber length, and microfibril angle (MFA). Segmented modeling approach was used to find juvenile and mature transition, and the SAS non-linear procedure (PROC NLIN) was employed to identify the juvenile to mature transition ring. Fiber length and MFA appear to be the good anatomical indicators of ring demarcation between juvenile and mature wood, although maturation ring varies slightly between the fiber length and MFA. The use of ring density, MOR, and MOE were not appropriate, because of low coefficients of determination and large range of segmented rings for transition from juvenile to mature wood. The maturation rings were estimated to start at segmented rings 17 and 18 by the fiber length, 18 and 20 by the MFA for sengon and jabon respectively. The projected figures for the portion of juvenile wood both in sengon and jabon in the breast height stem at the age of 7 years were 100 %. As a result of this study, the consequent careful attentions should be given for the use of the jabon and sengon woods by some wood-processing technologies.