The effect of mortality diseases on wood quality of sissoo (Dalbergia sissoo Roxb)
M M Islam, M O Hannan, G N M Ilias
Sissoo (Dalbergia sissoo Roxb.) is a lagre deciduos, fast growing, strong light demanding and leguminous tree specie. It is an important multipurpose specie widely being planted in the agro forestry and and social forestry pratices in Bangladesh, particularly in the north and south-western parts of the country. On account of its better quality, sissoo is valued as good as construction and utility timber in Bangladesh. It is used as high value timber, wood fuel, nitrogen fixing and fodder trees. For about a decade, sissoo plantings of varying ages have been found dying due to an unknown cause. By 1996 the mortality was wide spread especially in the western part of the country, and it affects the wood properties of sissoo. The wood properties are very important in selecting wood for numerous uses. So, a comparative study of various physical properties of wood among sound, moderately affected and severally affected sissoo trees was conducted. Sound, moderately affected and severally affected sissoo trees showed significant differences in respect of tangential, radial, longitudinal and volumentric shrinkage respectively. Radial shrinkage didn’t differ significantly among top, middle and bottom sections of a particular condition of wood and the same result was of tangential, longitudinal and volumetric shrinkage. The same trees also showed a significant difference in density, but the density didn’t differ significantly among the top, middle or bottom sections of a particular condition of wood. Besides these, the presence of decay, stain, tunnel and discolouration were observed which also determine the wood quality. In sound, sissoo wood these are absent, but in disease affected sisso wood decay, stain, tunnel and discolouration are present which deteriorate the wood quality. It is observed that the wood quality of sound sissoo trees have been found superior to that of moderately affected and severally affected wood.