Wood quality studies of some wood species in Sudano-Sahelian Environment of Borno State, Nigeria
This study investigates wood properties of Azadirachta indica, Eucalyptus camaldulensis, and Khaya senegalensis to determine their potentials for timber in Nigeria. The species were randomly selected from a Forestry and Wildlife Nursery plantation within University of Maiduguri, Borno State in the North-eastern part of Nigeria. Three sampled trees were felled approximately 15cm to the ground and neatly de-branched. From each tree, 3 discs of 6cm height and a billet of 30cm were cut from each bole making a total of 9 discs and 3 billets from each stem, and 27 discs were taken at three height levels: base, middle and top of the merchantable height (MH) to determine their physical properties. Selected wood properties varied considerably among the species (P < 0.05). Wood density, annual ring, bark, sapwood and hardwood proportions decreased from the base to the top while moisture content, bast and pith proportions increased from base to top of the all the species along the sampling heights. The hygroscopicity of the wood shows that longitudinal shrinkage increased from base to top of all the selected species and others do not follow a particular pattern. This results however, when compared with other research results on bark portion shows the juvenility of the sample tress. The shrinkage behaviour of this species are low and indicates that the problems of cracking, splitting, opening of joint and warping in service will be minimal. The average annual ring of the selected species is estimated to be 6 A. indica, 5 in E. camaldulensis and 6 in K. senegalensis, this showed that the trees are still at the juvenile sap stage.
Keywords: Azadirachta indica, Eucalyptus camaldulensis, Khaya senegalensis Wood quality, Hygroscopicity