Some Basic Physical And Mechanical Properties Of The Valuable Hagenia abyssinica Timber And Their Interactions: Imlpication For Its Rational Utilization

Abstract

Among the overlooked major causes in Ethiopia that led to the destruction of forests, inappropriate utilization and endangering of the valuable tree species such as Hagenia abyssinica are lack of technical information on basic properties of wood and its utilization methods. The objective of this study was, therefore, to determine the basic physical and mechanical properties of H. abyssinica at green and dry conditions, their interactions and effect on its timber utilization. The study showed that there was significant difference (p<0.01) in green and air dry values of moisture content (MC), density and mechanical properties namely, static bending, compression parallel and perpendicular to the grain, side hardness indentation and impact bending along height among the trees of H. abyssinica. Seasoning from green state (88%) to 12% MC has resulted in increase in mechanical properties of 41% in modulus of rupture, 13% in modulus of elasticity, 65% in compression parallel and 50% perpendicular to the grain and 30% in side hardness. The results show that MC affects density and in turn both strongly affect the mechanical property of H. abyssinica timber. The lower the MC, the lower the volume, the higher the oven dry density and the higher the mechanical properties of the species. Therefore, for lumber utilization and planning for sustainable management of H. abyssinica, it is appropriate to select the right density, dimension, mechanical properties and loading direction of this species.

Keywords: Density; Hagenia abyssinica; Mechanical properties; Moisture content; Seasoning of wood; Uses.

Ethiopian Journal of Biological Sciences Vol. 5 (2) 2006: pp. 117-135