Use of wood characteristics in Identification of selected Terminalia species growing in Sri Lanka

Abstract

250 timber species are being used by the timber industry in Sri Lanka and among them building constructors, furniture manufacturers and wood fabricators are the main consumers. Identification of the trees become very difficult once felled and processed and therefore macroscopic/ microscopic features and physical properties of timber become important. Timber identification is necessary for right use of timber and to check on fraud in timber trading as some timber traders deceive customers by mixing low value timber with high quality ones. Five timber species of Terminalia namely T. arjuna (Kumbuk), T. bellirica (Bulu), T. catappa (Kottamba), T. chebula (Aralu) and T. parviflora (Hampalanda) of the family of Combretaceae were studied anatomically in search of sufficient features to separate one Terminalia sp from the other. Due to the resemblance of wood structure of five Terminalia spp, examination of the transverse sections of wood with a hand lens (×25) does not provide adequate reliable information to differentiate one species from the other for identification. Hence Transverse section (T.S.), radial longitudinal section (R.L.T.) and tangential longitudinal section (T.L.S.) were obtained using the microtome for the anatomical examination. In this study, some important wood anatomical and non-anatomical features were studied according to IAWA (1989). It was found that all Terminalia spp had diffuse porous wood having vessels mainly solitary and occasionally in 2-3 of radial multiples. Mean vessel diameter and vessel diameter range were recorded respectively as 241μm and 172-331μm in T. arjuna, 169μm and 107-204μm in T. bellirica, 240μm and 169-309μm in T. catappa, 115μm and 68-175μm in T. chebula and 124μm and 75-159μm in T. parviflora. Mean vessel frequency were observed as 3 per mm2 in T. arjuna, 4 per mm2 in T. bellirica, 3 per mm2 in T. catappa, 6 per mm2 in T. chebula and 5 per mm2 in T. parviflora. Mean rays frequency, mean ray height and mean ray width were found respectively as 9 per mm, 206μm, 24μm in T. arjuna, 11 per mm, 283μm, 24μm in T. bellirica, 8 per mm, 280μm, 25μm in T. catappa, 13 per mm, 239μm, 31μm in T. chebula and 10 per mm, 235μm, 30 μm in T. parviflora. Ray cell arrangement is mostly uniseriate and occasionally biseriate in T. bellirica, T. parviflora and T. arjuna. Ray cell arrangement is mostly multiseriate and occasionally uniseriate in T. catappa while T. chebula has uniseriate ray cell arrangement. Different type of axial parenchyma types were found in each Terminalia species. T. bellirica had axial parenchyma band (more than three cells wide). T. parviflora and T. catappa had aliform/vasicentric type axial parenchyma which can be differentiated from confluent parenchyma type in T. chebula. Vasicentric (halo) parenchyma types were found mainly in T. arjuna. Finally, it can be concluded that ray cell arrangement and axial parenchyma types can be used together as baseline to distinguish Terminalia spp in Sri Lanka for the purpose of timber identification.