The Study of the Motors Affecting the Natural Resistance of the Wood of Terminalia Ivorensis against Termite Attack

ABSTRACT

The natural Radial and axial variations in the resistance of the wood of Termihalia ivorensis A* Chev, against damage by subterranean termites were investigated for two trees from the same locality- The damage was studied in relation to specific gravity, the modulus of elasticity, the cross-sectional area of vessels in the wood,, and the water soluble extractives. The correlation between termite damage and these physical, mechanical and anatomical properties have been reported. It was found that the termite resistance of the wood varied significantly in the radial direction. The outer-heartwood was less susceptible to damage than the sapwood and the inner-heartwood, The sapwood was less resistant to damage than the inner-heartwood. The termite resistance of the inner-heartwood increased near the top of the tree. Axial variations in the intensity of termite damage were not very pronounced. Termite damage to the wood was inversely correlated with the specific gravity and cross-sectional area of the vessels generally. The susceptibility to damage by termites generally increased with the modulus of elasticity. The specific gravity, modulus of elasticity and the cross-sectional area of the vessels were inter-correlated and no one of them could be used alone to predict the termite resistance of T, ivorensis, The water soluble extractives appeared not to improve on the resistance of the wood. The two trees tested showed significant differences in their resistance to termite attack. This means that naturally growing trees of T„ ivorensis obtained from different Forest Reserves in Ghana could be expected to vary widely in their resistance against attack by subterranean termites.

The natural Radial and axial variations in the resistance of the wood of Termihalia ivorensis A* Chev, against damage by subterranean termites were investigated for two trees from the same locality- The damage was studied in relation to specific gravity, the modulus of elasticity, the cross-sectional area of vessels in the wood,, and the water soluble extractives. The correlation between termite damage and these physical, mechanical and anatomical properties have been reported. It was found that the termite resistance of the wood varied significantly in the radial direction. The outer-heartwood was less susceptible to damage than the sapwood and the inner-heartwood, The sapwood was less resistant to damage than the inner-heartwood. The termite resistance of the inner-heartwood increased near the top of the tree. Axial variations in the intensity of termite damage were not very pronounced. Termite damage to the wood was inversely correlated with the specific gravity and cross-sectional area of the vessels generally. The susceptibility to damage by termites generally increased with the modulus of elasticity. The specific gravity, modulus of elasticity and the cross-sectional area of the vessels were inter-correlated and no one of them could be used alone to predict the termite resistance of T, ivorensis, The water soluble extractives appeared not to improve on the resistance of the wood. The two trees tested showed significant differences in their resistance to termite attack. This means that naturally growing trees of T„ ivorensis obtained from different Forest Reserves in Ghana could be expected to vary widely in their resistance against attack by subterranean termites.