5133

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

Combretocarpus Hook. f.

Benth. & Hook. f., Gen. pl. 1: 683 (1865).

ANISOPHYLLEACEAE

x = unknown; 2n = unknown

Brunei: balak bekatan, keruntum, perapat hutan. Indonesia: perepat darat (general, trade name), marapat (Dayak Ngaju, Kalimantan), teruntum batu (Bangka). Malaysia: keruntum (general, Sarawak), perapat paya, perapat perapat (Sabah).

Combretocarpus is a monotypic genus. The only species, Combretocarpus rotundatus (Miq.) Danser (synonym: Combretocarpus motleyi Hook. f.), is distributed in Sumatra, Borneo, and intervening islands (Riau Archipelago, Bangka, Belitung). It is most abundant in Sarawak and Brunei and has only once been collected in Peninsular Malaysia.

The wood of C. rotundatus is locally highly favoured for heavy interior construction and railway sleepers, but needs preservation for the latter purpose. It is also used for temporary construction exposed to the weather, furniture, flooring, panelling, boat construction, agricultural implements, sliced veneer and firewood. Posts are sometimes used for live fencing.

Owing to its abundance, C. rotundatus is potentially one of the most important timbers of Sarawak. However, so far only small amounts have been imported by Japan from Sarawak.

C. rotundatus yields a medium-weight hardwood with a density of 635-870 kg/m³ at 15% moisture content. The heartwood is reddish-brown and generally distinct from the grey-white sapwood, which turns grey-brown upon exposure; grain straight to interlocked; texture coarse and uneven; radial and tangential surfaces exhibit an attractive silver grain figure. Growth rings indistinct or absent; vessels medium-sized to moderately large, mostly solitary, less often in radial multiples of up to 4, white deposits commonly present; wood parenchyma variable, generally apotracheal diffuse-in-aggregates tending to arch between the broad rays; rays moderately broad to very broad, broad rays distinct; ripple marks absent; crystals visible on transverse section.
Shrinkage upon seasoning is low to rather high; there is a slight risk of warping, splitting or end-checking. The wood dries slowly and it takes 3 and 6 months to dry 13 mm and 38 mm thick boards, respectively. In Malaysia kiln schedule G is recommended. The timber is worked fairly easy with hand and machine tools, though has a tendency to spring during sawing. The nailing properties are rated as poor. The wood is rated as moderately durable for outside uses, but is durable under cover. It is not resistant to marine borer attack and absorbs a mixture of 50% creosote and 50% diesel oil moderately well (95-130 kg/m³).
See also the tables on microscopic wood anatomy and wood properties.

A medium-sized to fairly large tree up to 40 m tall; bole usually straight (sometimes crooked and twisted), up to 100 cm in diameter, without buttresses, clustered stilt roots sometimes present, in swamps sometimes with mats of thread-like rusty brown aerial roots; bark surface irregularly and deeply fissured, fawn to greyish-brown, inner bark hard, orange-brown; crown usually irregular, with twisted branches. Leaves alternate, simple, entire, cuneate at base, rounded at apex; stipules absent. Flowers in a paniculate, axillary inflorescence, yellow, 3(-4)-merous; calyx lobes deltoid-ovate; petals linear, entire or sometimes laciniate; stamens twice the number of the petals; ovary inferior, 3(-4) locular with 2 ovules in each cell, styles 3(-4), free. Fruit dry, 1-seeded, broadly 3-winged. Seed spindle-shaped.
The young leaves are conspicuously bright crimson to dark red.
Combretocarpus is related to Anisophyllea. Both genera are often included in the family Rhizophoraceae. However, recent multidisciplinary research has shown that they can best be placed in a separate family Anisophylleaceae.

C. rotundatus grows on waterlogged soils of peat-swamp forest and kerangas up to 100(-300) m altitude. It occurs most abundantly in secondary forest or forest with an open canopy, but there the trees are often small and of poor form. In Sarawak well-developed trees are found in peat-swamp forest associated with alan (Shorea albida Sym.).

Propagation and planting have not been practised, but as the tree coppices vigorously, regeneration of logged-over forest will pose no problem. Fallen trees usually develop adventitious shoots from the bole and these eventually develop into trees. Even posts used for fencing and similar purposes often root and sprout. In some localities the trunk of old trees is hollow. Green logs sink in water. In large areas of Sarawak and Brunei there are more than 5 large trees of C. rotundatus per ha on average.

C. rotundatus does not seem to be endangered as it is commonly found over large areas and regenerates particularly well after disturbance of the swamp forest.

As early as the 1950s it was recognized that this timber has good prospects. However, to date it does not seem to be exported in substantial quantities and is used only locally. Comparatively large supplies are available, and the wood shows good properties and an attractive silver grain figure. However, additional research is still needed on the proper management of swamp forest from which this timber can be sustainably harvested.

[40]All Nippon Checkers Corporation, 1989. Illustrated commercial foreign woods in Japan. Tokyo. 262 pp.
[61]Ashton, P.S., 1988. Manual of the non-dipterocarp trees of Sarawak. Vol. 2. Dewan Bahasa dan Pustaka, Kuala Lumpur. 490 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.
[259]den Berger, L.G., 1926. Mechanical properties of Dutch East Indian timbers. Korte Mededeelingen No 12. Proefstation voor het Boschwezen, Buitenzorg. viii + 63 pp.
[267]Desch, H.E., 1941-1954. Manual of Malayan timbers. Malayan Forest Records No 15. 2 volumes. Malaya Publishing House Ltd., Singapore. 762 pp.
[341]Flora Malesiana (various editors), 1950-. Kluwer Academic Publishers, Dordrecht, Boston, London.
[464]Ilic, J., 1990. The CSIRO macro key for hardwood identification. CSIRO, Highett. 125 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.
[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.
[1221]Whitmore, T.C. & Ng, F.S.P. (Editors), 1972-1989. Tree flora of Malaya. A manual for foresters. 4 volumes. Malayan Forest Records No 26. Longman Malaysia Sdn. Berhad, Kuala Lumpur & Petaling Jaya.
[1242]Wong, T.M., 1982. A dictionary of Malaysian timbers. Malayan Forest Records No 30. Forest Research Institute Malaysia, Kepong. 259 pp.

E. Boer & R.H.M.J. Lemmens

Boer, E. & Lemmens, R.H.M.J., 1998. Combretocarpus Hook. f.. 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