Radial variation in fiber length of some lesser used wood species in Nigeria
Variations in fibre length of ten lesser used wood species were investigated. The mean fibre length varied from 1.07mm in Lannea acida to 2.41mm in Sterculia setigera. Four patterns of within tree radial variations in fibre length were observed in the studied species. In pattern one, fibre length increased from the pith to the bark. This was observed in Butyrospermum paradoxum, where fibre length increased from 1.43 mm in the heartwood to 1.45mm in the transition wood and 1.46mm in the sapwood; and in Parinarium kerstingii, where fibre length increased from 1.33mm in the heartwood to 1.40mm in the transition wood and to 1.42 mm in the sapwood. The same pattern of radial variation was also observed in Detarium senegalense where fibre length increased from 0.95mm in the heartwood zone to 0.96 mm in the transition wood and subsequently to 1.19 mm in the sapwood zone. In pattern two, fibre length decreased from the heartwood (pith) to the bark as observed in Isoberlina doka and Annogeissus leiocarpus. Fibre length decreased from 1.52mm in the heartwood of I. doka to 1.40 mm and 1.31 mm in the transition and sapwood of the plant species respectively. Also fibre length decreased from 1.30 mm in the heartwood of A. leiocarpus to 1.27mm and finally to 1.22 mm in the sapwood of A. leiocarpus. In pattern three, fibre length increased from the heartwood to the transition wood and decreased to the bark. This was observed in Parkia felicoida and Sterculia setigera where fibre length increased from 1.19 mm in the heartwood of P. felicoida to 2.47mm to 1.33mm in the transition wood and decreased to 1.19mm in the sapwood. In Sterculia setigera fibre length increased from 2.47mm in the hearwood to 2.50 mm in the transition wood and decreased to 2.26 mm in the sapwood of the species. In the 4th pattern, fibre length decreased from 1.49 mm in the heartwood to 0.96 mm in the transition wood followed by an increase to 1.19 mm in the sapwood zone of Mitragyna inermis.
KEY WORDS: Radial Variation, Fibre Length, Heartwood, Transition Wood, Sapwood