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

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 sp

Properties of Celtiz zenkeri Engel: a lesser-known timber species from Kilindi District, Tanzania

This study was conducted to provide some of the basic physical and strength properties of wood of Celtis zenkeri Engel. which is among the lesser-known and lesser-utilized timber species from Tanzania. Celtis zenkeri belonging to the family Ulmaceae is currently being harvested for wood fuel and building poles thus being under-valued and placed in class V timbers since the basic properties of its wood are not yet known. The objective of this study was therefore, to determine and assess some of the basic physical and mechanical properties of C. zenkeri specifically colour, texture, basic density, Static bending (Modulus of Flasticity, Modulus of Rupture, Work to maximum Load and Total work), Compression parallel to grain, Shear and Cleavage stress. Relationships between basic density and the mechanical properties were also assessed. Data for this study were collected from three mature and defect free sample trees objectively selected from Kilindi district in Tanga region. Each sample tree produced three logs; from bottom, middle and upper part of the bole. Test specimens were extracted from the samples and by using standard methods, the physical and mechanical properties were determined. The following are the wood strength properties obtained for C. zenkeri. Basic density (655 kg m-3) and Total Work (21,916 N mm-2), Modules of rapture (198 N mm-2), Work to maximum load (0.360 N mm-3) and Total Work (0.598 N mm-2). Others are; Cleavage strength (24.56 N mm-width), compression strength (97.1 N mm-2) and Shear strength (28.7 N mm-1) Celtis zenkeri wood was found to have desirable values to be used for hand tools, joinery, building, plywood, artificial limbs and flooring furniture.Key words: Basic density - Tanga, Khaya anthotheca, Eucalyptus paniculata, Fagaropsis angolensi

Properties of Manilkara Discolor (Sond.) Hemsl.): a lesser-known timber species from Kilindi District Tanzania

This work was conducted to determine some physical and mechanical properties of Manilkara discolor, a lesser-known and lesser-utilized timber species from Kilindi District Tanzania. Three large trees free from visible defects were selected, felled and small sample pieces of 20 mm x 20 mm x 60 mm for compression, 20 mm x 20 mm x 20 mm for shear, 20 mm x 20 mm x 45 mm for cleavage and 20 mm x 20 mm x 300 mm for static bending, comprising 72 pieces for each test were prepared. The sample pieces were tested in laboratory using standard methods. The wood was brownish and attractive, fine textured with appealing figure and attaining good finish when plained. The results showed the species to have wood basic Density of 765 kg m-3, Modulus of Elasticity of 14,341 N mm-2, Modulus of Rupture of 119.48 Nmm-2, Work to Maximum Load of 0.132 mm Nmm-2 and Work to Total Fracture of 0.284 mm Nmm-2. The Compression parallel to grain was 41.69 Nmm-2, Shear parallel to grain was 18.65 Nmm-2 and Cleavage Strength was 34.97 Nmm-2. Manilkara discolor wood was found to have desirable values and can be used to substitute other species which are currently in danger of over-exploitation.Key words: Basic density – Tanga - Khaya anthotheca - Pterocarpus angolensi

Some Physical And Strength Properties Of Lesser Known Aphloia theiformis Timber From Lushoto Tanga, Tanzania

Some physical and strength properties of lesser known Aphloia theiformis timber grown in and around Magamba Forest Reserve, Lushoto district, Tanga region were determined. A total of three sample trees were randomly selected and felled for this study. Test samples for moisture content, basic density and Strength properties determination were prepared and tested according to Lavers (1969), BS 373 (1957), ISO 3130 (1975), ISO 3131 (1975), ISO 3133 (1975) and ISO 3349 (1975). It was observed that Aphloia theiformis timber has a sapwood and heartwood colour ranging from creamcoloured to whitish pink resembling that of Grevillea robusta. The average basic density was 519 kg/m3 with a standard deviation of 4.2 which can be classified as medium-density timber. The basic density showed a slight decrease from butt end to top end. Regarding strength properties, Aphloia theiformis timber had a mean modulus of rupture of about 55.8 N/mm2 and modulus of elasticity of about 3854 N/mm2. The work to the maximum load was about 0.06mmN mm-3, while total work averaged 0.08mmN mm-3. The compression and shear parallel to the grain were 37.4 and 12.6N mm-2 respectively. Furthermore, all strength properties of Aphloia theiformis were positively correlated with basic density. The properties of this timber were also comparable to properties of Grevilea robusta and are always rated the same by timber dealers. While Aphloia theiformis had higher tearing strength than Grevillea robusta, the modulus of rupture and compression parallel to the grain values were comparable. Aphloia theiformis can therefore substitute Grevilea robusta in many areas of its application. Keywords: Aphloia theiformis - lesser known - physical and strength propertiesTanzania Journal of Forestry and Nature Conservation Vol. 77 2008: pp. 1-