Ocotea usambarensis

Family

Lauraceae

Synonyms

Vernacular names

East African camphor wood (En). Camphrier (Fr). Mkulo, mukongo (Sw).

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Origin and geographic distribution

Ocotea usambarensis occurs in eastern DR Congo, Rwanda, Kenya, Uganda, Tanzania, northern Malawi and northern Zambia. It is planted on a small scale in Kenya and Tanzania.

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Uses

The wood, often traded as ‘camphor’, is valued for joinery, panelling, poles for building, doors, window frames, shutters, furniture, cabinet work, vehicle bodies, sliced veneer and plywood. It is used for flooring of local houses and for implements. The wood is suitable for construction, ship building, boxes, crates, vats, matches and pulpwood. It is less suitable for draining boards and kitchen utensils because of the camphor-like smell. It is also used as firewood and for charcoal production.
Bark and roots are used in traditional medicine. The pounded bark of roots, bole and branches is applied to swellings, boils and wounds. A bark decoction is given to treat whooping cough and measles. Bark powder is taken against stomach-ache. Roots steeped in water are taken to treat malaria and back pain. Ocotea usambarensis is occasionally planted as an ornamental shade tree, but its crown is too dense to be useful for agroforestry purposes.

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Production and international trade

Ocotea usambarensis is traded internationally in limited amounts, but there are no statistics on production and trade of the timber. In 2000–2001 in Kenya it was the most highly priced timber species. Exploitation of the bark for medicinal purposes is considerable, but there is no information on amounts.

Properties

The heartwood is pale yellowish brown when freshly cut, darkening to deep brown upon exposure, and sometimes lustrous; it is not distinctly demarcated from the slightly paler sapwood. The grain is usually interlocked, texture even and moderately fine to fine. Quarter-sawn surfaces show a stripe or ribbon figure. The wood has a distinct camphor-like smell.
The wood is medium-weight, with a density of 450–640 kg/m³ at 12% moisture content. It air dries slowly with little degrade, although severe case-hardening may occur. Drying of thick boards may be problematic. Boards 2.5 cm thick take about 3 months to air dry, boards 5 cm thick about 6 months. The rates of shrinkage are moderately low, from green to oven dry 2.5–4.1% radial and 5.0–6.7% tangential. Once dry, the wood is quite stable in service.
At 12% moisture content, the modulus of rupture is 75–92 N/mm², modulus of elasticity 9900–11,100 N/mm², compression parallel to grain 37–53 N/mm², shear 11–15 N/mm², cleavage about 11 N/mm, Janka side hardness 2840–4310 N and Janka end hardness 5070–5120 N.
The wood is easy to saw, and it works satisfactorily with both hand and machine tools; the blunting effect on cutting edges is small. A 15–20° cutting angle is recommended in sawing and planing to avoid picking up of interlocked grain. In nailing the wood has a tendency to split at the edges or ends, but the nail-holding power is satisfactory. Gluing and staining do not give problems, but the use of a filler is required for optimum polishing results. It is rarely peeled because logs are rarely sound at the centre. The steam bending properties are moderate. The wood is moderately durable to durable. It is very resistant to decay but can be susceptible to termite and marine borer attacks, and the sapwood to powder-post beetle attack. The heartwood is very resistant to impregnation by preservatives, the sapwood moderately resistant.
In in-vitro tests, methanol extracts of the root bark showed pronounced cytotoxic activity against several human cancer cell lines at 100 μg/ml. Bark extracts showed antifungal activity against Cladosporium cucumerinum. This activity was linked to the presence of the lignan (+)-piperitol and an essential oil, in which nerolidol, α-terpineol, α-copaen-11-ol and an unidentified sesquiterpene alcohol were the main active compounds.

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Description

Evergreen, small to fairly large tree up to 35(–45) m tall; bole usually straight, often slightly fluted, branchless for up to 15(–20) m, up to 200(–300) cm in diameter, with small buttresses at base; bark surface greyish brown to reddish brown, fissured, scaling off in round or square flakes, inner bark white to pale pink, with sweet, camphor-like scent; crown dense, spreading; twigs slender, angular, hairy. Leaves alternate to opposite, simple and entire; stipules absent; petiole 0.5–2 cm long; blade ovate to elliptical, (2.5–)4–17 cm × (2–)2.5–9 cm, cuneate to rounded or truncate at base, usually acuminate at apex, thinly leathery, glossy dark green above, silvery white below, slightly hairy at least on veins, pinnately veined with 6–8 pairs of lateral veins, with camphor smell. Inflorescence an axillary panicle up to 13 cm long, densely yellowish brown hairy; peduncle 2–8 cm long. Flowers bisexual or unisexual, regular; pedicel 1–4 mm long; perianth lobes 6, ovate-elliptical, 2–3 mm long, greenish yellow or whitish yellow, short-hairy; stamens 9 in 3 whorls, anthers 4-celled, stamens of inner whorl with 2 glands at base, staminodes forming a fourth whorl around the ovary; ovary superior, ovoid, c. 1 mm long, glabrous, 1-celled, style c. 1 mm long, stigma disk-shaped; male flowers with reduced ovary, female flowers with reduced stamens. Fruit an ellipsoid to nearly globose drupe-like berry c. 1 cm long, green to orange-brown, at base enclosed in the cup-like enlarged receptacle c. 3 mm long, 1-seeded.

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Other botanical information

The estimated number of species in Ocotea ranges from 200 to 350 species, most of them in tropical America. Mainland Africa has about 7 species, Madagascar about 35.

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Anatomy

Wood-anatomical description (IAWA hardwood codes):
Growth rings: 2: growth ring boundaries indistinct or absent. Vessels: 5: wood diffuse-porous; 13: simple perforation plates; (14: scalariform perforation plates); (15: scalariform perforation plates with ≤ 10 bars); (16: scalariform perforation plates with 10–20 bars); 22: intervessel pits alternate; 23: shape of alternate pits polygonal; 27: intervessel pits large (≥ 10 μm); 32: vessel-ray pits with much reduced borders to apparently simple: pits horizontal (scalariform, gash-like) to vertical (palisade); 42: mean tangential diameter of vessel lumina 100–200 μm; 47: 5–20 vessels per square millimetre; 56: tyloses common. Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 66: non-septate fibres present; 69: fibres thin- to thick-walled. Axial parenchyma: 78: axial parenchyma scanty paratracheal; 92: four (3–4) cells per parenchyma strand. Rays: 97: ray width 1–3 cells; 106: body ray cells procumbent with one row of upright and/or square marginal cells; (107: body ray cells procumbent with mostly 2–4 rows of upright and/or square marginal cells); 115: 4–12 rays per mm. Secretory elements and cambial variants: 124: oil and/or mucilage cells associated with ray parenchyma; (125: oil and/or mucilage cells associated with axial parenchyma).
(P. Ng’andwe, H. Beeckman & P.E. Gasson)

Growth and development

Records of growth rates of Ocotea usambarensis are contradictory. Growth rates of up to 2 m/year have been recorded for young trees, but this seems to be exceptional. In a 75-year-old plantation at 2450 m altitude in Kenya, trees were 15–29 m tall, with a bole diameter of 19–51 cm. The mean annual diameter increment was 6.2 mm until 18 years after planting, but thereafter decreased gradually to 4.4 mm at 75 years old. It was suggested that the initial spacing (1.5 m × 1.5 m) was too close to enable good growth. In Tanzania 49-year-old trees were 15–24.5 m tall, with a mean bole length of 10 m and mean bole diameter of 40–49 cm. It was recorded that 90% of the trees showed heart rot, ranging from 4–24% of the log volume, but in another study 60% of the trees was recorded to be free of heart rot.
Trees may produce fruits in large amounts, but usually only once in 3–4 years, so-called mast years. They often develop root suckers, but these are often eaten by large animals such as elephants. Regeneration by suckering and coppicing is high after clear felling.

Ecology

Ocotea usambarensis occurs in rainforest at 900–2600(–3000) m altitude. The mean annual rainfall in the area of distribution ranges from (1200–)1600 mm to 2450 mm, with often 2–3 dry months, and a mean annual temperature of (12–)16–20(–26)°C. Ocotea usambarensis may be dominant in mountain forest. It prefers deep, fertile soils with good drainage.

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Propagation and planting

The 1000-seed weight is about 150 g. Fresh seed should be used for sowing. The germination rate is often low, up to 45%. Seeds are often heavily attacked by insects. They usually start germinating in 30–45 days, but germination may take up to 90 days. Seeds should be cleaned from the surrounding pulp before sowing by rubbing in water. Seed is sensitive to desiccation, but can be stored for a short period in moist saw dust.
Propagation by root suckers is easy; these are often produced abundantly. Under natural conditions, Ocotea usambarensis regenerates mainly by suckers because undamaged seed is uncommon. After natural breakdown of an old tree, the gap is first filled by fast-growing pioneer species, in the shade of which the Ocotea usambarensis suckers can establish, and after death of the pioneer species they can develop into new trees.

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Management

Ocotea usambarensis is mainly harvested from natural stands, and the extent of plantations is very limited and confined to Kenya and Tanzania. Large-scale logging leads to secondary forest types in which Ocotea usambarensis does not play a significant role because of lack of regeneration.
In plantations a heavy first thinning is recommended 15–20 years after planting, reducing the stock to about 700 trees/ha, with subsequent thinnings at intervals of 7–10 years. Rotation cycles of 60–70 years have been practised in Tanzania, but these may be reduced to 50 years with proper thinning regimes to finally 220 trees/ha. Trees can be managed by coppicing, to which they respond well at any age.

Diseases and pests

Fruits are often heavily attacked by insects. Standing older trees often show heart rot caused by fungi such as Ganoderma applanatum and Fomes spp. The bark of young trees is stripped by squirrels and tree hyraxes and the leaves are browsed by elephants.

Handling after harvest

The logs of large trees often have rotten cores, and boles are sometimes ill-shaped or have much twisted grain. This makes selection of logs before sawing for different purposes important.

Genetic resources and breeding

In Kenya and Tanzania Ocotea usambarensis was dominant in many mountain forests, the so-called ‘ocotea forest’, but it occurs more sparsely in Uganda. However, it has become rare throughout East Africa due to over-exploitation and is officially protected in Kenya and Tanzania. Illegal logging is still widespread, and conservation measures seem to be necessary.

Prospects

Ocotea usambarensis seems to have good prospects as a plantation timber tree, providing wood of excellent quality. Although it is considered valuable and has been over-exploited, very little research has been done on its growth rates and propagation methods. The common use of the bark in local medicine warrants more research on the pharmacological activities and on sustainable collection of the bark.

Major references

• 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.
• Diniz, M.A., 1997. Lauraceae. In: Pope, G.V. (Editor). Flora Zambesiaca. Volume 9, part 2. Royal Botanic Gardens, Kew, Richmond, United Kingdom. pp. 45–59.
• Farmer, R.H., 1972. Handbook of hardwoods. 2nd Edition. Her Majesty’s Stationery Office, London, United Kingdom. 243 pp.
• Hines, D.A. & Eckman, K., 1993. Indigenous multipurpose trees of Tanzania: Uses and economic benefits for people. [Internet] Cultural Survival Canada, Ottawa, Canada. http://www.fao.org/ documents/show_cdr.asp?url_file=/docrep/X5327e/ x5327e1c.htm. Accessed May 2008.
• Kigomo, B.N., 1987. The growth of camphor (Ocotea usambarensis Engl.) in plantation in the eastern Aberdare range, Kenya. East African Agricultural and Forestry Journal 52(3): 141–147.
• Maundu, P. & Tengnäs, B. (Editors), 2005. Useful trees and shrubs for Kenya. World Agroforestry Centre - East and Central Africa Regional Programme (ICRAF-ECA), Technical Handbook 35, Nairobi, Kenya. 484 pp.
• Mbuya, L.P., Msanga, H.P., Ruffo, C.K., Birnie, A. & Tengnäs, B., 1994. Useful trees and shrubs for Tanzania: identification, propagation and management for agricultural and pastoral communities. Technical Handbook 6. Regional Soil Conservation Unit/SIDA, Nairobi, Kenya. 542 pp.
• Takahashi, A., 1978. Compilation of data on the mechanical properties of foreign woods (part 3) Africa. Shimane University, Matsue, Japan, 248 pp.
• Tanzania Forest Division, 1965. Timbers of Tanganyika: Ocotea usambarensis (East African camphorwood). Tanzania Forest Division, Utilisation Section, Moshi, Tanzania. 6 pp.
• World Agroforestry Centre, undated. Agroforestree Database. [Internet] World Agroforestry Centre (ICRAF), Nairobi, Kenya. http://www.worldagroforestry.org/ Sites/TreeDBS/ aft.asp. Accessed May 2008.

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Other references

• Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
• Bryce, J.M., 1967. The commercial timbers of Tanzania. Tanzania Forest Division, Utilisation Section, Moshi, Tanzania. 139 pp.
• Bussmann, R.W., 2001. Succession and regeneration patterns of East African mountain forests: a review. Systematics and Geography of Plants 71(2): 959–974.
• CAB International, 2005. Forestry Compendium. Ocotea usambarensis. [Internet] http://www.cabicompendium.org/ fc/datasheet.asp?ccode=ocotus&country=0. Accessed May 2008.
• Chudnoff, M., 1980. Tropical timbers of the world. USDA Forest Service, Agricultural Handbook No 607, Washington D.C., United States. 826 pp.
• Dale, I.R. & Greenway, P.J., 1961. Kenya trees and shrubs. Buchanan’s Kenya Estates Limited, Nairobi, Kenya. 654 pp.
• Dick, J.H., 1969. Heartwood development and heart-rot in East African camphorwood, Ocotea usambarensis Engl. Tanzania Silviculture Research Note No 9. 3 pp.
• Fleuret, A., 1980. Nonfood uses of plants in Usambara. Economic Botany 34(4): 320–333.
• InsideWood, undated. [Internet] http://insidewood.lib.ncsu.edu/search/. Accessed May 2007.
• Kamuhabwa, A., Nshimo, C. & de Witte, P., 2000. Cytotoxicity of some medicinal plant extracts used in Tanzanian traditional medicine. Journal of Ethnopharmacology 70: 143–149.
• Katende, A.B., Birnie, A. & Tengnäs, B., 1995. Useful trees and shrubs for Uganda: identification, propagation and management for agricultural and pastoral communities. Technical Handbook 10. Regional Soil Conservation Unit, Nairobi, Kenya. 710 pp.
• Kimariyo, P.E., 1971. Regeneration of Ocotea usambarensis Engl. at Sungwi, West Usumbara. Tanzania Silviculture Research Note No 21. 3 pp.
• Kokwaro, J.O., 1993. Medicinal plants of East Africa. 2nd Edition. Kenya Literature Bureau, Nairobi, Kenya. 401 pp.
• Mugasha, A.G., 1978. Some effects of heavy thinning on the growth of Ocotea usambarensis Engl. at Barankata, Kilimanjaro region. Tanzania Silviculture Technical Note No 38. 9 pp.
• Mugasha, A.G., 1980. The relationship between crown diameter and breast height diameter for Ocotea usambarensis Engl. as a guide to a feasible stocking in second regeneration stands. Tanzania Silviculture Research Note No 38. 15 pp.
• Ndangalasi, H.J., Bitariho, R. & Dovie, D.B.K., 2007. Harvesting of non-timber forest products and implications for conservation in two montane forests of East Africa. Biological Conservation 134(2): 242–250.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Terreaux, C., Maillard, M., Hostettmann, K., Lodi, G. & Hakizamungu, E., 1994. Analysis of the fungicidal constituents from the bark of Ocotea usambarensis Engl. (Lauraceae). Phytochemical Analysis 5(5): 233–238.
• Troupin, G., 1982. Flore des plantes ligneuses du Rwanda. Publication No 21. Institut National de Recherche Scientifique, Butare, Rwanda. 747 pp.
• Verdcourt, B., 1996. Lauraceae. In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 19 pp.
• Wimbush, S.H., 1957. Catalogue of Kenya timbers. 2nd reprint. Government Printer, Nairobi, Kenya. 74 pp.

Afriref references

Sources of illustration

• Diniz, M.A., 1997. Lauraceae. In: Pope, G.V. (Editor). Flora Zambesiaca. Volume 9, part 2. Royal Botanic Gardens, Kew, Richmond, United Kingdom. pp. 45–59.
• Katende, A.B., Birnie, A. & Tengnäs, B., 1995. Useful trees and shrubs for Uganda: identification, propagation and management for agricultural and pastoral communities. Technical Handbook 10. Regional Soil Conservation Unit, Nairobi, Kenya. 710 pp.

Author(s)

•	J.M. Okeyo TSBF-CIAT, World Agroforestry Centre (ICRAF), P.O. Box 30677, Gigiri, Nairobi, Kenya

Editors

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

General editors

•	R.H.M.J. Lemmens PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
•	L.P.A. Oyen PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
•	J.R. Cobbinah Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Photo editor

•	G.H. Schmelzer PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands

Correct citation of this article

Okeyo, J.M., 2008. Ocotea usambarensis Engl. [Internet] Record from PROTA4U. Louppe, D., Oteng-Amoako, A.A. & Brink, M. (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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