Prota 7(1): Timbers/Bois d’œuvre 1
Bull. Jard. Bot. Etat 19: 494 (1949).
Tylostemon kweo Mildbr. (1914).
Origin and geographic distribution
Beilschmiedia kweo is endemic to the Eastern Arc mountains in Tanzania.
The wood is used for furniture, flooring, panelling, veneer, gun stocks and tool handles. It is also suitable for light construction, interior trim, joinery, shipbuilding, sporting goods, agricultural implements, toys, novelties, turnery, poles, piles and mine props. It is also used as fuelwood.
Production and international trade
Appreciable volumes of the wood were formerly used locally in Tanzania and exported to Germany, where it was used for wagons and ships. Nowadays it is scarce.
The heartwood is olive green, on drying darkening to greenish brown or chestnut brown; it is distinctly demarcated from the cream coloured and up to 5 cm-wide sapwood. The grain is straight, texture medium. The wood is oily.
The density of the wood is 540–740 kg/m³ at 12% moisture content. Shrinkage rates are 1.8% radial and 4.1% tangential from green to 12% moisture content, and 3.0% radial and 6.8% tangential from green to oven dry. Air-drying is slow, with material more than 2.5 cm thick having a tendency to split. Material 2.5 cm thick can be kiln-dried satisfactorily. Logs may develop star shakes a few weeks after felling. Dried wood is stable in service.
At 12% moisture content, the modulus of rupture is 79 N/mm², modulus of elasticity 11,100 N/mm², compression parallel to grain 45 N/mm², shear 10 N/mm², cleavage 65 N/mm radial and 76 N/mm tangential, and Janka side hardness 4320 N.
The wood saws well, but with a tendency to split when star shakes are present, and with a marked blunting effect on sawteeth. The wood planes well, but only at low speed, otherwise tearing may occur. It moulds, bores and mortises cleanly, sands and polishes to a clean finish, and glues well. The nailing properties are poor, and pre-boring is necessary near edges. Turning is easy.
The durability of the wood is moderate to high, and it is moderately resistant to marine borers and termites. The sapwood is liable to attack by Lyctus beetles. The heartwood is impermeable to preservatives, the sapwood moderately resistant to impregnation.
Evergreen, medium-sized tree up to 30 m tall; bole branchless for up to 15(–25) m, straight, up to 100 cm in diameter, without buttresses; outer bark pale grey or pale brown, nearly smooth, flaking in large scales leaving liver-coloured patches, inner bark red; young branches finely hairy. Leaves alternate or opposite, simple and entire; stipules absent; petiole 1.5–2 cm long; blade oblong-ovate to elliptical or oblong, (10–)11.5–18(–22) cm × 4–9(–11) cm, base broadly cuneate to rounded, apex narrowly acuminate, glabrous, pinnately veined with c. 10 pairs of lateral veins. Inflorescence an axillary panicle, lax, 4–6 cm long; peduncle c. 5 cm long; branches up to 3 cm long. Flowers bisexual, regular, dark red; pedicel c. 2 mm long; perianth top-shaped to bell-shaped; tube c. 1.5 mm long, lobes 6, ovate, c. 1.5 mm long; fertile stamens (6–)9, in (2–)3 whorls of 3, inner whorl with glands, staminodes 3; ovary superior, at top gradually narrowing into the style. Fruit an ellipsoid olive-like berry 3.5–5 cm × 1.5–2.5 cm, 1-seeded. Seed with semicircular, very thick, pale violet-brown cotyledons.
Only 12% of seeds of Beilschmiedia kweo were recorded to germinate after 2 months, rising to 70% after 3 months, indicating physiological dormancy. The seed is recalcitrant.
Beilschmiedia comprises about 250 species and is distributed throughout the tropics, with about 80 species in tropical Africa and Madagascar. Beilschmiedia kweo is classified in subgenus Stemonadenia, section Hufelandia.
Beilschmiedia kweo occurs in rainforest at 800–1800 m altitude. In the East Usambara mountains (Tanzania) the species shows good natural regeneration in old Maesopsis eminii Engl. plantations.
Genetic resources and breeding
Beilschmiedia kweo is classified as vulnerable in the 2006 IUCN Red list of threatened species, due to its limited distribution area.
In view of its limited distribution and scarcity due to former exploitation there is no scope for increased use of Beilschmiedia kweo as a source of timber, and it should rather be protected or managed, for example in former Maesopsis eminii plantations.
• Bolza, E. & Keating, W.G., 1972. African timbers: the properties, uses and characteristics of 700 species. Division of Building Research, CSIRO, Melbourne, Australia. 710 pp.
• Bryce, J.M., 1967. The commercial timbers of Tanzania. Tanzania Forest Division, Utilisation Section, Moshi, Tanzania. 139 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan, 248 pp.
• Verdcourt, B., 1996. Lauraceae. In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 19 pp.
• Baskin, C.C. & Baskin, J.M., 2005. Seed dormancy in trees of climax tropical vegetation types. Tropical Ecology 46(1): 17–28.
• CAB International, 2005. Forestry Compendium. Beilschmiedia kweo. [Internet] http://www.cabicompendium.org/ fc/datasheet.asp?CCODE=BEILKW. Accessed January 2008.
• Lovett, J. & Clarke, G.P., 1998. Beilschmiedia kweo. In: IUCN. 2006 Red list of threatened species. [Internet] http://www.iucnredlist.org. Accessed December 2006.
• Lovett, J.C., Ruffo, C.K., Gereau, R.E. & Taplin, J.R.D., 2006. Field guide to the moist forest trees of Tanzania. [Internet] Centre for Ecology Law and Policy, Environment Department, University of York, York, United Kingdom. http://www.york.ac.uk/ res/celp/webpages/projects/ecology/ tree%20guide/guide.htm. Accessed December 2006.
• Robyns, W. & Wilczek, R., 1949. Contribution à l’étude des Lauracées du Congo Belge et de l’Afrique tropicale. Bulletin du Jardin Botanique de l’Etat (Bruxelles) 19(4): 457–507.
• Roe, D., Mulliken, T, Milledge, S., Mremi, J., Mosha, S. & Grieg-Gran, M., 2002. Making a killing or making a living?: wildlife trade, trade controls and rural livelihoods. Biodiversity and Livelihoods Issues 6. TRAFFIC, Cambridge & IIED, London, United Kingdom. 114 pp.
• Sautu, A., Baskin, J.M., Baskin, C.C. & Condit, R., 2006. Studies on the seed biology of 100 native species of trees in seasonal moist tropical forest, Panama, Central America. Forest Ecology and Management 234(1–3): 245–263.
• Viisteensaari, J., Johansson, S., Kaarakka, V. & Luukkanen, O., 2000. Is the alien tree species Maesopsis eminii Engl. (Rhamnaceae) a threat to tropical forest conservation in the East Usambaras, Tanzania? Environmental Conservation 27(1): 76–81.
Correct citation of this article:
Brink, M., 2008. Beilschmiedia kweo (Mildbr.) Robyns & R.Wilczek. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.