Properties of <i>Nesogordonia Holtzh</i> subsp <i>Hotzii</i> (Moss) capuron: a lesser known timber species from Kilindi District, Tanzania

Abstract

Nesogordonia holtzii subsp holtzii (Moss) Capuron is a lesser-known timber species belonging to the family Sterculiaceae. The species is distributed in the eastern tropical Africa in association with other tree species as Newtonia buchananii, Albizia versicolor, Allanblackia stuhlmanii, Antiaris toxicaria and Sterculia appendiculata. Currently it is harvested for fuelwood and building poles thus being under-valued, Due to its wood technical properties not known to users it is placed in royalty fee class V timbers. The objective of this study was therefore to determine and assess some basic physical and mechanical properties of N. holtzii. Compare the determined strength properties of N. holtzii with those from well known tree species. Use different combinations of the properties of N. holtzii obtained to assign suitable end uses and promote it for its utilization. Three mature sample trees free from visible defects were selected randomly. Each tree was sampled to produced three logs. Test specimens were extracted from the sample logs using the method by Larvers (1969). Physical and strength properties determination was carried out according to the procedure described in ISO 3131(1975) ISO3133 (1975) BS 373(1957, 1976) Larvers (1969) and Panshin and de Zeeuw (1970). The results showed that N. holtzii was found to have yellow timber that turns reddish brown on seasoning and the wood is fine textured. The average basic density is 593 kg m-3 Modulus of Elasticity 7,606 N/mm-3, Modulus of Rupture 81 N/mm-2, Work to Maximum Load 0.098 N mm-3, Total Work 0.196 N mm-3, Compression Stress 48.83 N mm- 2, Shear Stress 11.40 N mm-2 and Cleavage Strength 24.98 N mm-1. These properties are within the acceptable range for the building and furniture industry. As many traditional timbers become scarcer, the timber of Nesogordonia holtzii should be promoted and is recommended as a substitute for Afzelia quanzensis, Pterocarpus angolensis and Newtonia buchananii. The resemblance in colour allows these timber species to be sold in one group.

Key words: Basic density – Tanga - Olea hochstteter – Brachystergia spp