Afzelia pachyloba Harms

Family

Caesalpiniaceae (Leguminosae - Caesalpinioideae)

Synonyms

Vernacular names

Afzelia (En). Doussié, doussié blanc (Fr).

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Origin and geographic distribution

Afzelia pachyloba occurs from southern Nigeria east to the Central African Republic, and south to Cabinda (Angola).

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Uses

Like other Afzelia spp., the wood of Afzelia pachyloba is characterized by an excellent stability with little susceptibility to variations in humidity, small shrinkage rates during drying and a good natural durability. The wood is durable and treatment with preservatives is unnecessary, even for usage in permanent humid conditions or in localities where wood-attacking insects are abundant. This makes it an excellent wood for use in pleasure-crafts, especially for keels, stems and panels, for bridges, as well as interior fittings. For such uses it is sometimes as much in demand as teak. The wood is also valued for joinery and panelling, both interior and exterior, parquet floors, doors, frames, stairs, vehicle bodies, furniture, sporting goods, mine props, musical instruments, railway sleepers, agricultural implements, utensils, tool handles, turnery, fibre board and particle board. It is suitable for decorative sliced veneer. Because of its good resistance to many chemical products and great dimensional stability, it is often preferred to materials like metals and synthetics for vats and precision equipment in industrial applications. The neutral pH of the wood makes it suitable for applications in contact with vulnerable objects such as antiques and old books in libraries. However, it should not be used in contact with textiles under more humid conditions because of the presence of colorants. It is also used as firewood.
The seed aril is edible and reportedly sweet. The seed has been reported to be toxic but also as edible. The oil is used for cooking and in soap making, and the residual cake after pressing is fed to cattle. The aril is applied to chapped skin. Seeds are used as bait in traps for antelopes. Root decoctions are applied externally to treat kidney pain.

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Production and international trade

The wood of Afzelia pachyloba is commonly traded as ‘doussié’ on the international timber market, although it is often mixed with that of other species such as Afzelia bipindensis Harms. Cameroon is the main exporting country. In 2003 it exported 9900 m³ of sawn doussié wood and 47,750 m³ in 2005. In 2008 the export from Cameroon was 23,300 m³, in which Afzelia pachyloba contributed about 17,000 m³. The annual export of Afzelia pachyloba timber from Congo in 2004–2007 was on average 1500 m³ (mainly as logs). Gabon exported in the period 1991–1999 an average of 1350 m³/year of Afzelia pachyloba timber. In 2004 the export of logs from Gabon was 2300 m³, and 1600 m³ in 2005. In the Central African Republic Afzelia pachyloba is also considered a high-value timber species; in 2004 the export of Afzelia timber (doussié) was 6500 m³. In 2007 the export of Afzelia pachyloba logs from the Central African Republic was 2200 m³ and 1250 m³ in 2008.

Properties

The heartwood is pale red-brown to orange-brown or golden brown, becoming red-brown upon long exposure, sometimes with darker streaks, and distinctly demarcated from the whitish to pale yellow, up to 7 cm wide sapwood. The grain is straight to interlocked, texture medium to coarse but even. The wood is slightly glossy and dried wood has a leather-like smell upon planing.
The wood is medium-weight to rather heavy, with a density of 720–840 kg/m³ at 12% moisture content. Drying usually does not cause problems, without deformation and splitting, but the wood dries slowly. For thick boards (more than 7.5 cm), preliminary air drying under cover is recommended before kiln drying. The shrinkage rates are low, from green to oven dry 2.6–3.6% radial and 4.0–5.5% tangential. Once dry, the wood is very stable in service.
At 12% moisture content, the modulus of rupture is 100–120 N/mm², modulus of elasticity 16,000–18,500 N/mm², compression parallel to grain 70–80 N/mm², shear 7–10 N/mm², cleavage 18–22 N/mm, Janka side hardness 7500–8500 N and Chalais-Meudon side hardness 6.9–8.6.
The wood saws easily when good equipment is used; it contains little silica (less than 0.015%) and stellite-tipped saw teeth are not needed for sawing fresh wood. Some logs have gum pockets, which may cause problems in sawing by blunting saw teeth. Tungsten-carbide-tipped cutting tools are recommended in planing and moulding operations. It is advisable to reduce the cutting angle to 15° to avoid rough surfaces when interlocked grain is present. The use of a filler is recommended to obtain smooth surfaces. The nailing and screwing properties are satisfactory, but pre-boring is recommended to avoid splitting. Gluing may be difficult. The wood paints and varnishes well, but wood zones close to the centre of the log may contain anti-oxidant substances that slow down drying of varnish and may cause problems in painting. The steam bending properties are satisfactory, but the presence of gum may cause problems. Sliced veneer of good quality can be produced, but the wood is not used for peeling. The wood has a good reputation for its resistance to acids and alkalines.
The heartwood is durable, with an excellent resistance to fungal, termite and borer attacks, but with only moderate resistance to marine borers. The sapwood is susceptible to Lyctus attack. The heartwood is resistant to impregnation with preservatives. Saw dust may cause allergic reactions, irritation of mucous membranes and asthma in wood workers.
Logs may have crevices filled with a whitish powdery substance originating from the wood vessels; the substance consists of kaempferol and derivatives. Kaempferol and its glycosides have antibacterial, antifungal and anti-inflammatory activities. The wood contains about 32.5% cellulose, 24.5% lignin and 15% pentosan. The solubility is about 23% in alcohol-benzene and 20% in a 1% NaOH solution. An average oil content of 28% has been recorded for the seeds. The major components of the oil are crepenynic acid (21%) and dehydrocrepenynic acid (27%). Crepenynic acid is a potential inhibitor of essential fatty acid metabolism, and proved toxic to sheep. Dehydrocrepenynic acid acts as inhibitor of conjugation in gram-negative bacteria, which may provide a means to control the spread of antibiotic resistance.

Adulterations and substitutes

The wood of three other Afzelia species is similar to that of Afzelia pachyloba and also traded as ‘doussié’: Afzelia africana Sm. ex Pers. and Afzelia bella Harms, both mainly exported from West Africa, and Afzelia bipindensis Harms, mainly exported from Central Africa. The excellent properties of Afzelia pachyloba wood concerning dimensional stability and high natural durability are comparable to some well-known timbers such as merbau (Intsia spp.) and teak (Tectona grandis L.f.), and to the African makore (Tieghemella heckelii (A.Chev.) Roberty) and douka (Tieghemella africana Pierre).

Description

Short-deciduous medium-sized to fairly large tree up to 40 m tall; bole branchless for up to 25 m, straight and cylindrical, up to 90(–150) cm in diameter, fluted at base or with small buttresses up to 1 m high; bark surface greyish to brown, irregularly scaly and with sinuous ridges, inner bark granular, creamy to yellowish brown, aromatic; crown elongate to rounded or flattened depending on age and growing conditions, with tortuous, more or less upright branches; young twigs short-hairy, soon becoming glabrous. Leaves alternate, paripinnately compound with (5–)7–10 pairs of leaflets; stipules with basal parts fused and persistent, upper parts free, linear and caducous; petiole and rachis together 6–20 cm long; petiolules 2–4 mm long, often slightly twisted; leaflets opposite, oblong to oblong-lanceolate, 2–6 cm × 1–2.5 cm, obtuse to notched, occasionally short-acuminate at apex, more or less short-hairy below, pinnately veined with 10–14 pairs of lateral veins. Inflorescence a terminal or axillary panicle up to 20 cm long, short-hairy. Flowers bisexual, zygomorphic, sweet-scented; pedicel 0.5–1 cm long; bracteoles c. 0.5 cm × 0.2 cm, caducous; hypanthium 1.5–2 cm long; sepals 4, slightly unequal, c. 1 cm long, densely short-hairy; petal 1, 3–4 cm long, with long claw, 2-lobed, white with red marking in the centre; fertile stamens 7 and 2.5–3 cm long, rudimentary stamens 2 and c. 1 cm long; ovary superior, c. 0.5 cm long, with short stipe, slightly hairy, style 2–3 cm long. Fruit a kidney-shaped, flattened pod 13–20 cm × 9–13 cm, brown, dehiscing with 2 woody valves, up to 15-seeded. Seeds ovoid-ellipsoid, 3–5.5 cm long, black, with cup-shaped to slightly 2-lobed yellow aril, covering the seed for up to 1/4.

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Other botanical information

Afzelia comprises about 11 species, 7 of which occur in tropical Africa and 4 in South-East Asia. It is closely related to Intsia.

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Anatomy

Wood-anatomical description (IAWA hardwood codes):
Growth rings: 1: growth ring boundaries distinct. Vessels: 5: wood diffuse-porous; 13: simple perforation plates; 22: intervessel pits alternate; 23: shape of alternate pits polygonal; 26: intervessel pits medium (7–10 μm); 29: vestured pits; 30: vessel-ray pits with distinct borders; similar to intervessel pits in size and shape throughout the ray cell; 43: mean tangential diameter of vessel lumina ≥ 200 μm; 46: ≤ 5 vessels per square millimetre; 58: gums and other deposits in heartwood vessels. Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 66: non-septate fibres present; 69: fibres thin- to thick-walled. Axial parenchyma: 80: axial parenchyma aliform; 81: axial parenchyma lozenge-aliform; 82: axial parenchyma winged-aliform; 83: axial parenchyma confluent; 86: axial parenchyma in narrow bands or lines up to three cells wide; 89: axial parenchyma in marginal or in seemingly marginal bands; 92: four (3–4) cells per parenchyma strand. Rays: 97: ray width 1–3 cells; 104: all ray cells procumbent; 115: 4–12 rays per mm. Mineral inclusions: 136: prismatic crystals present; 142: prismatic crystals in chambered axial parenchyma cells.
(N.P. Mollel, A.A. Oteng-Amoako & H. Beeckman)

Growth and development

In Gabon flowering trees have been recorded in December, and in Cameroon in June and November.

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Ecology

Afzelia pachyloba occurs in evergreen and semi-deciduous forest up to 200 m altitude, usually on well-drained localities. It is often found in secondary forest.

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Management

Afzelia pachyloba usually occurs scattered and in low densities in the forest. In western Cameroon an average wood volume of 1 m³/ha has been recorded for trees with a bole diameter of more than 60 cm. In Gabon Afzelia pachyloba appears to occur in even lower densities.

Harvesting

The minimum bole diameter for harvesting is 80 cm in Cameroon and the Central African Republic. The recommended minimum bole diameter for harvesting in Gabon is 70 cm.

Handling after harvest

Prolonged stocking of logs after harvesting does not cause problems except occasional black holes in the sapwood caused by borer attacks. Logs of Afzelia pachyloba are too heavy to be transported by river.

Genetic resources and breeding

Afzelia pachyloba is included in the IUCN Red List of threatened species as vulnerable because of intensive exploitation. In some regions it has been reported that few older trees producing seeds remained after exploitation of the forest.

Prospects

Afzelia pachyloba may have prospects as a commercial plantation timber, although it does not grow rapidly. The high value of its wood makes it economically interesting. More research is needed on its growth rate, propagation and appropriate methods of management to reduce the existing pressure on natural stands.

Major references

• ATIBT (Association Technique Internationale des Bois Tropicaux), 1986. Tropical timber atlas: Part 1 – Africa. ATIBT, Paris, France. 208 pp.
• 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.
• Burkill, H.M., 1995. The useful plants of West Tropical Africa. 2nd Edition. Volume 3, Families J–L. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 857 pp.
• CTFT (Centre Technique Forestier Tropical), 1963. Résultats des observations et des essais effectués au Centre Technique Forestier Tropical sur le doussié: Afzelia spp., A. bipindensis, A. pachyloba, A. africana. Information techinique No 184, CTFT, Nogent-sur-Marne, France. 9 pp.
• CTFT (Centre Technique Forestier Tropical), 1980. Doussié. Bois et Forêts des Tropiques 189: 37–54.
• de Saint-Aubin, G., 1963. La forêt du Gabon. Publication No 21 du Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 208 pp.
• Gérard, J., Edi Kouassi, A., Daigremont, C., Détienne, P., Fouquet, D. & Vernay, M., 1998. Synthèse sur les caractéristiques technologiques des principaux bois commerciaux africains. Document Forafri 11. Cirad, Montpellier, France. 185 pp.
• Sallenave, P., 1955. Propriétés physiques et mécaniques des bois tropicaux de l’Union française. Centre Technique Forestier Tropical, Nogent sur Marne, France. 129 pp.
• Sallenave, P., 1971. Propriétés physiques et mecaniques des bois tropicaux. Deuxième supplément. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 128 pp.
• Vivien, J. & Faure, J.J., 1985. Arbres des forêts denses d’Afrique Centrale. Agence de Coopération Culturelle et Technique, Paris, France. 565 pp.

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Other references

• African Regional Workshop (Conservation & Sustainable Management of Trees, Zimbabwe), 1998. Afzelia pachyloba. In: IUCN. 2010 IUCN Red list of threatened species. Version 2010.4. [Internet] http://www.iucnredlist.org. Accessed January 2011.
• Aubréville, A., 1968. Légumineuses - Caesalpinioidées (Leguminosae - Caesalpinioideae). Flore du Gabon. Volume 15. Muséum National d’Histoire Naturelle, Paris, France. 362 pp.
• Aubréville, A., 1970. Légumineuses - Césalpinioidées (Leguminosae - Caesalpinioideae). Flore du Cameroun. Volume 9. Muséum National d’Histoire Naturelle, Paris, France. 339 pp.
• Christy, P., Jaffré, R., Ntougou, O. & Wilks, C., 2003. La forêt et la filière bois au Gabon. Projet Aménagement Forestier et Environnement, Libreville, Gabon. 389 pp.
• Chudnoff, M., 1980. Tropical timbers of the world. USDA Forest Service, Agricultural Handbook No 607, Washington D.C., United States. 826 pp.
• CIRAD Forestry Department, 2009. Doussie. [Internet] Tropix 6.0. http://tropix.cirad.fr/ africa/ doussie.pdf. Accessed January 2011.
• Fouarge, J., Quoilin, J. & Roosen, P., 1970. Essais physiques, mécaniques et de durabilité de bois de la République Democratique du Congo. Série technique No 76. Institut National pour l’Etude Agronomique du Congo (INEAC), Brussels, Belgium. 40 pp.
• Hausen, B.M., 1981. Woods injurious to human health: a manual. Walter de Gruyter & Co., Berlin, Germany. 189 pp.
• Kazadi, M. & Chifundera, K., 1993. Acetylenic fatty acids from Afzelia pachyloba. Fitoterapia 64(3): 280.
• Koch, G., Richter, H.G. & Schmitt, U., 2006. Topochemical investigation on phenolic deposits in the vessels of afzelia (Afzelia spp.) and merbau (Intsia spp.) heartwood. Holzforschung 60: 583–588.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Normand, D. & Paquis, J., 1976. Manuel d’identification des bois commerciaux. Tome 2. Afrique guinéo-congolaise. Centre Technique Forestier Tropical, Nogent-sur-Marne, France. 335 pp.
• Raponda-Walker, A. & Sillans, R., 1961. Les plantes utiles du Gabon. Paul Lechevalier, Paris, France. 614 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan. 248 pp.
• Wilczek, R., Léonard, J., Hauman, L., Hoyle, A.C., Steyaert, R., Gilbert, G. & Boutique, R., 1952. Caesalpiniaceae. In: Robyns, W., Staner, P., Demaret, F., Germain, R., Gilbert, G., Hauman, L., Homès, M., Jurion, F., Lebrun, J., Vanden Abeele, M. & Boutique, R. (Editors). Flore du Congo belge et du Ruanda-Urundi. Spermatophytes. Volume 3. Institut National pour l’Étude Agronomique du Congo belge, Brussels, Belgium. pp. 234–554.
• Wilks, C. & Issembé, Y., 2000. Les arbres de la Guinée Equatoriale: Guide pratique d’identification: région continentale. Projet CUREF, Bata, Guinée Equatoriale. 546 pp.

Sources of illustration

• Aubréville, A., 1970. Légumineuses - Césalpinioidées (Leguminosae - Caesalpinioideae). Flore du Cameroun. Volume 9. Muséum National d’Histoire Naturelle, Paris, France. 339 pp.
• Wilks, C. & Issembé, Y., 2000. Les arbres de la Guinée Equatoriale: Guide pratique d’identification: région continentale. Projet CUREF, Bata, Guinée Equatoriale. 546 pp.

Author(s)

•	J. Gérard UPR Production et valorisation des bois tropicaux et méditerranéens, 73 rue Jean-François Breton, TA B-40 / 16 (Bât. 16, Bur. 123), 34398 Montpellier Cédex 5, France
•	D. Louppe CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C 105 / D (Bât. C, Bur. 113), 34398 Montpellier Cédex 5, France

Editors

•	R.H.M.J. Lemmens PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
•	D. Louppe CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C 105 / D (Bât. C, Bur. 113), 34398 Montpellier Cédex 5, France
•	A.A. Oteng-Amoako Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Associate editors

•	E.A. Obeng Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Correct citation of this article

Gérard, J. & Louppe, D., 2011. Afzelia pachyloba Harms. [Internet] Record from PROTA4U. Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. <http://www.prota4u.org/search.asp>. Accessed .

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