5179

5(3): Timber trees; Lesser-known timbers

Dactylocladus Oliv.

Hook. Icon. Pl.: t. 2351 (1895).

CRYPTERONIACEAE

x = unknown; 2n = unknown

Jongkong (trade name). Merubong (En, Fr). Brunei: medang tabak, tabak. Indonesia: mentibu (Indonesian), merebung, sampinur (Kalimantan). Malaysia: medang miang (Kedayan, Sabah), medang tabak, tabak (Sabah, Sarawak), merebong (Iban, Sarawak).

Dactylocladus is a monotypic genus endemic to Borneo. The only species, D. stenostachys Oliv., is especially abundant in Sarawak. This species, or one closely related to it, may be present in Irian Jaya.

Exported wood of Dactylocladus is mainly used for furniture, drawers and interior construction. Local uses include concrete shuttering, weatherboard, flooring, interior construction, utility furniture, shopfitting, partitioning and occasionally the production of veneer and plywood. Its specialty applications include broomheads, seats of plush furniture, Venetian blind slats and boat building. Treated the wood has been used for shingles and window frames. It is also suitable for the manufacture of particle board.

D. stenostachys is the third most important swamp timber exported from Sarawak, after ramin (Gonystylus spp.) and meranti (Shorea spp.), and is traded as a "light hardwood"". In 1987 exports from Sarawak to Japan comprised 41,500 logs, which is 5.2% of the total export from Sarawak to Japan. In 1988 the total export of D. stenostachys sawlogs from Sarawak was 254 650 m³ (with a value of about US$ 10.2 million) but this decreased steadily to 186 750 m³ in 1993 (about US$ 15.5 million). The majority (90%) was exported to Japan, the rest to Taiwan, Singapore, Denmark, China, Australia and Kuwait. The export of D. stenostachys sawn timber from Sarawak amounted to 6020 m³ (US$ 1.1 million) in 1988 but had fallen to 1720 m³ (US$ 447 000) in 1993. In 1987 the export of D. stenostachys from Sabah was only 183 m³ with a value of US$ 11 000, and in 1992 it amounted to 598 m³ of sawn timber and 898 m³ of logs with a value of US$ 141 500 and US$ 61 000 respectively. The comparatively high export figures are due not so much to the favourable properties of the timber as to its availability.

D. stenostachys is a lightweight to medium-weight hardwood with a density of 410-610 kg/m³ at 15% moisture content. Heartwood pale brown, almost white when fresh, darkening to pink-brown or red-brown, usually with white flecks, not clearly demarcated from the sapwood; grain straight to slightly interlocked; texture moderately fine and even, except for the radial breakdown areas. Growth rings indistinct; vessels moderately small to medium-sized, predominantly solitary, but also in radial multiples of 2-3, open; parenchyma scanty paratracheal, and aliform to confluent; rays fine and indistinct to the naked eye; ripple marks vague; radial breakdown areas characteristically appear as small lenticular flecks or holes on tangential surfaces, sometimes mistaken for pinhole borer attack.
Shrinkage is low to moderate and the wood seasons fairly slowly: it takes about 3 months and 5 months respectively to air dry boards 13 mm and 38 mm thick. It seasons without serious degrade provided it is protected from sap-stain although some bowing and end-checking may occur in air drying and slight collapse in kiln drying; kiln schedule K is recommended in Malaysia. The wood is soft to moderately hard, and fairly weak. It is very easy to work, peels readily and phloem flecks do not pose problems. It can be planed to a fairly lustrous finish. The wood is non-durable, but can be treated with preservatives without difficulty. It is not resistant to termites and marine borers, but is rarely attacked by pinhole borers. The sapwood is susceptible to Lyctus.
The energy value of the wood is 19 810 kJ/kg. Fibres from the inner bark may cause itching or may be painful to the skin. Sawdust may cause nasal irritation.
See also the tables on microscopic wood anatomy and wood properties.

An evergreen, small to large tree up to 40 m tall; bole cylindrical or slightly fluted at base, usually short but sometimes branchless for up to 25 m, often with small burrs, up to 120(-150) cm in diameter, without buttresses, with many stout yellowish pneumatophores; bark surface becoming slightly to prominently fissured and scaly, red-brown to greyish-brown, inner bark fibrous, yellowish-brown and darkening upon exposure, without exudate; crown almost spherical with big branches. Twigs with swollen nodes and longitudinal lines. Leaves opposite, simple, margin entire, revolute, veins anastomosing in an indistinct intramarginal vein; stipules minute or rudimentary. Flowers in racemes united into an erect, poorly branched panicle, small, (4-)5-merous; receptacle puberulous; calyx with triangular lobes; petals spoon-shaped, white; stamens 5; ovary semi-inferior, (3-)4-5-locular with 3 ovules in each cell, stigma capitate. Fruit a many-seeded, almost inferior capsule, yellowish-green. Seed flat and surrounded by an almost rectangular membranous wing.
Flowers may be observed throughout the year, but most frequently in the middle of the dry season in June and July. Fruits take about 3 months to ripen and have been reported most often in September and October. The winged seeds are dispersed by wind.
Dactylocladus is sometimes treated as a member of the family Melastomataceae. Anatomical evidence seems to support this view, and it appears that the family Crypteroniaceae itself may be heterogenous. No definite decisions have been made yet on these complex matters.

D. stenostachys is one of the most abundant large canopy trees of peat-swamp forests in Sarawak and Brunei. It is represented in all types of swamp forest communities, but is most abundant and sometimes dominant in the Gonystylus-Dactylocladus-Neoscortechinia association (mixed swamp forest) and the Combretocarpus-Dactylocladus association. On the perimeter of peat-swamps D. stenostachys may attain a diameter of over 120 cm, while in the centre it may be very abundant but only rarely reaches 10 cm in diameter. In mixed peat-swamp forest especially the crowns of D. stenostachys trees are inhabited by many epiphytes and figs. D. stenostachys has also been found in kerangas vegetation on podzol soils, and in East Kalimantan it is an important element of the Cratoxylum glaucum-Dactylocladus stenostachys community. In general D. stenostachys demands an acid, poorly drained soil. It thrives in a perhumid climate, generally at low altitudes but sometimes up to 800 m.

Natural regeneration is scarce in primary and secondary forests. Very few seedlings can be found immediately after felling, but 10 years after clear felling saplings are found in widely dispersed gregarious groups of up to 30 individuals. The form of these trees, however, is poor and trees are almost invariably forked. This species' demand for light is unclear; reports are contradictory, some stating that it probably tolerates shade as saplings do not appear to respond vigorously to full light and others nothing that it has some pioneer features like natural regeneration in open areas as after clear felling. For Sarawak an average of over 3 large trees per ha is given for natural peat-swamp forest, but exceptional densities of up to 12 mature trees per ha have been reported. In Sarawak the estimated harvesting costs are US$ 11-14/m³.

D. stenostachys has been heavily exploited for some decades, but still seems fairly abundant. In Sarawak its natural regeneration is stimulated and therefore the risk of genetic erosion is low.

Relatively little is known on the silvicultural management of peat-swamp forest for the production of D. stenostachys. Ramin (Gonystylus spp.) is economically much more important and silvicultural practices are primarily geared to this species. Increased knowledge on the treatment and use of D. stenostachys timber may lead to an increase in its use.

[40]All Nippon Checkers Corporation, 1989. Illustrated commercial foreign woods in Japan. Tokyo. 262 pp.
[45]Anderson, J.A.R., 1963. The flora of the peat swamp forests of Sarawak and Brunei, including a catalogue of all recorded species of flowering plants, ferns and fern allies. Gardens' Bulletin, Singapore 20: 131-228.
[49]Anonymous. Macroscopic study of peat swamp forest timbers of Sarawak. Forest Department of Sarawak. 56 pp.
[51]Anonymous, 1975. Some Malaysian timbers from Sarawak. Borneo Literature Bureau, Sarawak. 92 pp.
[124]Bolza, E. & Kloot, N.H., 1963. The mechanical properties of 174 Australian timbers. Technological Paper No 25. Division of Forest Products, CSIRO, Melbourne. 112 pp.
[151]Browne, F.G., 1955. Forest trees of Sarawak and Brunei and their products. Government Printing Office, Kuching, Sarawak. xviii + 369 pp.
[162]Burgess, P.F., 1966. Timbers of Sabah. Sabah Forest Records No 6. Forest Department, Sabah, Sandakan. xviii + 501 pp.
[190]Cheng, J.S.K., Mamit, J. & Nibu, A.N., 1985. Strength properties of Sarawak timbers. Technical Report No TR/1. Forest Department Sarawak. 44 pp.
[193]Chudnoff, M., 1980. Tropical timbers of the world. Forest Products Laboratory, Forest Service, United States Department of Agriculture, Madison. 831 pp.
[341]Flora Malesiana (various editors), 1950-. Kluwer Academic Publishers, Dordrecht, Boston, London.
[387]Grewal, G.S., 1979. Air-seasoning properties of some Malaysian timbers. Malaysian Forest Service Trade Leaflet No 41. Malaysian Timber Industry Board, Kuala Lumpur. 26 pp.
[526]Kartasujana, I. & Martawijaya, A., 1979. Kayu perdagangan Indonesia - sifat dan kegunaannya [Commercial woods of Indonesia - their properties and uses]. Lembaga Penelitian Hasil Hutan, Bogor. 28 pp.
[529]Kartawinata, K., 1980. A note on a kerangas (heath) forest at Sebulu, East Kalimantan. Reinwardtia 9: 429-447.
[536]Keating, W.G. & Bolza, E., 1982. Characteristics, properties and uses of timbers. Vol. 1. South-East Asia, northern Australia and the Pacific. Inkata Press Proprietary Ltd., Melbourne, Sydney & London. 362 pp.
[568]Kingston, R.S.T. & Risdon, C.J.E., 1961. Shrinkage and density of Australian and other South-West Pacific woods. Technological Paper No 13. Division of Forest Products, CSIRO, Melbourne. 65 pp.
[675]Lee, H.S. & Chai, F., 1995. Sustainable forest management in the peat swamp forests of Sarawak. Forest Department Sarawak. 188 pp.
[741]Malaysian Timber Industry Board, 1986. 100 Malaysian timbers. Kuala Lumpur. x + 226 pp.
[756]Martawijaya, A., Kartasujana, I., Kadir, K. & Prawira, S.A., 1986. Indonesian wood atlas. Vol. 1. Forest Products Research and Development Centre, Bogor. 166 pp.
[771]Meijer, W., 1974. Field guide for trees of West Malesia. Missouri Botanical Garden, St. Louis. 328 pp.
[861]Oey Djoen Seng, 1951. De soortelijke gewichten van Indonesische houtsoorten en hun betekenis voor de praktijk [Specific gravity of Indonesian woods and its significance for practical use]. Rapport No 46. Bosbouwproefstation, Bogor. 183 pp.
[933]Research Institute of Wood Industry, 1988. Identification, properties and uses of some Southeast Asian woods. Chinese Academy of Forestry, Wan Shou Shan, Beijing & International Tropical Timber Organization, Yokohama. 201 pp.
[1040]Smythies, B.E., 1965. Common Sarawak trees. Borneo Literature Bureau, South China Morning Post, Hong Kong. 153 pp.
[1048]Soepadmo, E., Wong, K.M. & Saw, L.G. (Editors), 1995-. Tree flora of Sabah and Sarawak. Sabah Forestry Department, Forest Research Institute Malaysia and Sarawak Forestry Department, Kepong.
[1052]Stadelman, R.C., 1966. Forests of Southeast Asia. Princeton, Memphis, Tennessee. 245 pp.
[1077]Sutisna, U., 1985. Analisa komposisi jenis pohon hutan rawa gambut di Sei Mandor, Kalimantan Barat [Tree species composition analysis of peat swamp forests at Sei Mandor, West Kalimantan]. Buletin Penelitian Hutan 469: 39-66.
[1117]van Beusekom-Osinga, R.J. & van Beusekom, C.F., 1975. Delimitation and subdivision of the Crypteroniaceae (Myrtales). Blumea 22: 255-266.

L.C.J. Julaihi

Julaihi. L.C.J., 1998. Dactylocladus Oliv.. In: Sosef, M.S.M., Hong, L.T. and Prawirohatmodjo, S. (Editors): Plant Resources of South-East Asia No 5(3): Timber trees; Lesser-known timbers. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea