ASSESSING SOME WOOD QUALITY INDICATORS OF THE TALL-GROWING TREE OF TETRAPLEURA TETRAPTERA (PREKESE) FOR USE AS TRANSMISSION POLE

Abstract

Tetrapleura tetraptera commonly known as Prekese (Twi ) is one of the valuable multi-purpose indigenous tree species in the rainforest areas in West Africa. It is widely distributed throughout the high forest zone of Ghana. It however does relatively well in the transition zone of Ghana within the context of traditional agroforestry systems. The tree has a high socio-economic value among the Akans of Ghana. Its role as food flavouring cannot be over emphasized It is claimed by the local farmers to be of two types; the tall-growing type and the short growing type. The bole form of the tall-growing type has generated interest in researches about its potential use for poles as further contribution as a multi-purpose species. This thus necessitated the need for the basic knowledge in the other important characteristics of the tree that may potentate its use for poles. The aim of this study was therefore to assess some quality indicators of the tall-growing type of Prekese tree electricity poles. This was achieved through the assessment of the morphological properties (bole length and girth) of the tree, its sapwood width,density its air-drying characteristics its treatability with copper-chrome-arsenic (CCA) preservative under pressure and the laboratory test to determine its natural durability all of which are the Ghana. Standard approved facts or governing the selection of tree species for transmission poles. The study revealed good morphological properties with bole length range of 7 to 10.2m and a girth range of 560 to 1100mm.The sapwood width of the sample poles ranged between 12mm to 30mm.It gave a good preservative treatability to a retention range of 18.54 to 28.28kg /m3, and a penetration range of 15mm to 46mm. The study also revealed mean basic density of 613kg/m3 with a range of 456 to 725kg/m • 3 The outer heartwood was found to be non-durable whilst the inner heartwood was moderately durable. On the basis of the findings of the study, which compares favourably with that specified by the Ghana Standard GS 11 (1992), the use of the male type of T.tetraptera for transmission poles is thus possible. For successful exploitation of the T. tetraptera for poles therefore, complete or nearly complete treatment of the sapwood and the outer heartwood is recommended. To ensure sustainability of good quality bole, establishment of plantation of genotypes and phenotypes is recommended Calibration of the moisture meter settings for use on Prekese poles is recommended to ensure accurate measurement of moisture content of poles. To avoid powder post pest infestation treatment of Prekese poles with insecticides before air-drying is recommended.