Dryobalanops Gaertner f.
- Protologue: Fruct. 3: 49 (1805).
- Family: Dipterocarpaceae
- Chromosome number: x= 7; D. oblongifolia, D. sumatrensis: 2n= 14
Kapur: medium-heavy hardwood, e.g. Dryobalanops oblongifolia Dyer, D. sumatrensis (J.F. Gmelin) Kosterm. (until recently known as D. aromatica Gaertner f.).
- Borneo camphorwood, Brunei teak, Mahoborn teak (En).
- Capur (Fr)
- Indonesia: kamper (general)
- Malaysia: kapor, paiji (Sabah), kapur bukit (Sarawak).
The names with "camphor" and "teak" should be avoided in view of possible confusion with true camphor wood (Cinnamomum) and true teak (Tectona), respectively.
Origin and geographic distribution
Dryobalanops consists of 7 species and is confined to Peninsular Malaysia, Sumatra, Borneo and intervening islands. Two species (D. oblongifolia and D. sumatrensis) occur throughout this area, five others are confined to Borneo. Fossil records have shown that Dryobalanops occurred in West Java and southern India in the Tertiary.
Kapur is an important construction timber for local use. It is used for both heavy and light construction in locations free of termites. Contradictory reports have been published about its usefulness in conditions where the wood is in contact with the ground. Kapur is used for furniture, joinery and heavy-duty packing cases; also for joints and beams, columns, poles, mining timber, handles, toys and coffins. Treated kapur is generally used for wharf deckings, bridges, ship building, vehicle bodies and railway sleepers. As a flooring timber it is suitable for conditions with medium-heavy traffic. Kapur is extensively used for plywood.
The construction of chipboard from kapur is regarded as commercially unattractive because the product is not particularly good and the wood, being comparatively dense, is expensive to pulp. Paper made of kapur is not of high quality because of the short fibres; long-fibred material has to be added.
Camphor can be yielded in crystalline form from cavities in the wood or as an oil from holes cut in the trunk. In former times, the yield of this camphor from D. sumatrensis was commercially much more important than the timber. The Dutch East India Company traded this camphor and exported it to China and Japan. The camphor has about the same properties as true camphor (from Cinnamomum camphora (L.) Presl). Kapur camphor has been used medicinally both externally and internally against coughs, asthma, headache, pains in the stomach or liver, and diseases in the urino-generative system as well as against ulcers in mouth and nose, rheumatism, burns and wounded eyes. The camphor is also used in local ceremonies. The fruits (nuts) of some species are edible (e.g. D. sumatrensis and D. oblongifolia).
Production and international trade
Kapur is a commercially important timber, particularly in Borneo. The export of round logs from Sabah in 1987 was 863 000 m3 with a value of US$ 70 million, and in 1992 267 000 m3 of logs and 97 000 m3 of sawn timber with a total value of US$ 55 million. In Indonesia statistics on export of kapur are combined with those of keruing (Dipterocarpus spp.); the value of exported sawn timber of the combined group kapur/keruing was almost US$ 100 million in 1989. However, kapur only constituted about 18% of this value; the volume exported in 1989 was 83 000 m3. Kapur is also important in Peninsular Malaysia, where in 1992 the export of sawn timber was 80 000 m3 worth US$ 13 million.
Kapur is a moderately heavy timber. The colour of the heartwood is rose-red to dark reddish-brown; the sapwood is yellowish-brown or pinkish. The planed surface is not particularly lustrous and the radial section shows a faint stripe figure. The density of the wood is 600-940(-1010) kg/m3 at 15% moisture content. The grain is straight, shallowly to heavily interlocked or spiral, texture moderately coarse to coarse but even. Freshly cut wood has a distinct camphor-like odour which can be rather persistent in some species.
At 15% moisture content the modulus of rupture is 62-114 N/mm2, modulus of elasticity 10 900-18 700 N/mm2, compression parallel to grain 38-62 N/mm2, compression perpendicular to grain 5-6 N/mm2, shear 4-10.5 N/mm2, cleavage 39-56 N/mm radial and 51-65 N/mm tangential, Janka side hardness 2330-5910 N and Janka end hardness 2265-7320 N.
The rates of shrinkage are medium to high: from green to 15% moisture content 1.7-2.1% radial and 3.8-4.6% tangential, from green to 12% moisture content 2.1-3.5% radial and 3.8-8.0% tangential, and from green to oven dry up to 4.4% radial and 9.6% tangential. Kapur timber seasons without any real difficulty, but is somewhat prone to splitting, end checking and surface checking. It takes respectively 2 and 5 months to air dry 12 mm and 38 mm thick boards of D. sumatrensis. For kiln drying, schedule E is used in Malaysia. Boards of 25 mm thick of D. sumatrensis can be kiln dried from 50% to 10% moisture content in 14 days, which is comparatively long for medium-heavy hardwood. Kapur is prone to warping, surface checking and end splitting during kiln drying. The boards should be end-coated and properly stacked.
The working qualities of kapur are moderately good. When green, the timber is easy to saw, although sawteeth may become clogged by resin; dabbing the saw blade with diesel oil minimizes this problem. Dry timber is less easy to saw because of the presence of silica. Saws with tip-hardened teeth are needed. Cross cutting is generally easy. Planing, boring and turning are easy, giving a smooth to moderately smooth surface. The nailing property is rated as poor. Kapur does not take a high polish without some filling.
Kapur is commercially peeled for making plywood, but the frequent presence of pinholes lowers the grade of the veneer. The extractives present may interfere with the gluing process and cause occasional delamination, especially when kapur veneers are glued together.
Kapur timber has a rather exaggerated reputation for durability. It may be rapidly destroyed by termites and should not be used in contact with the ground in the tropics. However, it is resistant to fungi. Standard graveyard tests of sticks of D. sumatrensis, D. oblongifolia and D. rappa in Malaysia showed an average service life of 6.0, 1.9 and 2.5 years, respectively. The heartwood is resistant to impregnation with preservatives, even under pressure. The average absorbtion of an equal mixture of creosote and diesel fuel is 48 kg/m3. The sapwood is liable to attack by powder-post beetles, but is permeable for preservatives.
Wood of D. sumatrensis contains 60% cellulose, 27% lignin, 16% pentosan, 0.8% ash and 0.6% silica. The solubility is 2.7% in alcohol-benzene, 2.6% in cold water, 3.9% in hot water and 12.9% in a 1% NaOH solution. The energy value is 18 800 kJ/kg.
Borneo camphor, found in cavities in the wood of D. sumatrensis, is crystallized oil. It consists of almost pure borneol.
- Large or very large, occasionally medium-sized trees, up to 60(-75) m tall, with a straight, columnar bole, often branchless for 30 m or more and up to 150(-200) cm in diameter; buttresses well-developed and spreading; bark shaggily flaked, purplish-brown, the new bark yellowish-brown with very small lenticels; mature crown very large, but rather narrowly conical or dome-shaped, consisting of a few large and twisted branches; branchlets numerous, crowded towards the ends, slender and ribbed.
- Leaves alternate and simple, leathery, rounded to oblong, prominently acuminate, glossy green and with a camphor-like odour when crushed, with many, slender and straight secondary veins linked at the margin by a more or less visible intramarginal vein; petiole slender, distinctly channelled above; stipules linear, caducous.
- Inflorescence paniculate, lax and diffuse, few-flowered.
- Flowers bisexual, actinomorphic; calyx 5-lobed with imbricate, glabrous lobes; petals 5, united at base and falling from the tree to the ground in a rosette, white and glabrous; stamens c. 30, glabrous, with short, broad filaments connate at base and linear anthers crowned by small appendages; pistil 1, glabrous, with ovoid ovary, style c. 3 times longer than ovary, stigma minute.
- Fruit a comparatively large, glabrous nut, enclosed by but free from the fruit calyx which forms a cup at base with 5 subequal wings.
- Seed 1-2 cm long.
- Seedling with epigeal germination and 2 reniform, unequal, succulent cotyledons; first two pairs of leaves opposite, developed in one flush, next leaves arranged spirally.
- Heartwood pink-brown or red-brown, darkening on exposure to dark red-brown, clearly demarcated from the yellow-brown or pinkish sapwood (50-100 mm thick).
- Grain straight, occasionally wavy to interlocked.
- Texture medium to coarse, even; fiddleback figure sometimes present, fleck figure well pronounced on quartersawn wood, with medium lustre.
- Growth rings indistinct, but concentric bands of resin canals may give impression of growth rings on backsawn surfaces; vessels visible to the naked eye, tyloses variable, few to abundant; parenchyma moderately abundant, rays individually visible to the naked eye; ripple marks most prominent in D. sumatrensis, less so in other species, indistinct in D. rappa.
- Axial gum canals in tangential bands forming continuous lines, considerably smaller than vessels and filled with white contents, more obvious on backsawn surfaces.
- Freshly cut wood with pronounced camphor-like odour, persisting in D. sumatrensis.
- Growth rings indistinct. Vessels diffuse, (5-)8-12(-17)/mm2 (5/mm2 in D. fusca , 17/mm2 in D. rappa ), solitary (90-95%), remainder in pairs, round to oval, average tangential diameter (130-)160-220(-240)μm (130μm in D. rappa); perforation plates simple; intervessel pits rare, loosely alternate, vestured, pit border diameter 5-7μm; vessel-ray pits simple, rounded, with large apertures of c. 20μm; tyloses absent, or few to abundant.
- Vasicentric tracheids scarce to common.
- Fibres 1.5-1.7 mm long, non-septate, moderately thick- to thick-walled (in species with denser wood), pits indistinctly bordered to distinct and conspicuous, mainly in radial walls.
- Parenchyma paratracheal, incompletely vasicentric with an aliform tendency, sometimes diffuse tending to short aggregates, also surrounding canals; strand length 1-4 cells, distinctly storied in D. sumatrensis.
- Rays 4-6(-8)/mm, uniseriate and 3-6-seriate, the latter up to 1 mm high, weakly heterocellular with 1-3 rows of square to upright marginal cells (Kribs type heterogeneous III and II), uniseriates few, short; sheath cells occasionally present.
- Silica bodies sparse in parenchyma cells of D. beccarii and D. oblongifolia; coloured deposits common; silica bodies abundant in ray cells (sparse in D. rappa).
- Prismatic crystals in chambered strands of parenchyma in D. keithii, D. lanceolata, D. oblongifolia, abundant in D. rappa.
- Horizontal intercellular canals absent.
- Axial intercellular canals in tangential lines or bands, average diameter of gum canals 40-70μm, commonly occluded with chalky white deposits.
Species studied: D. beccarii, D. fusca, D. keithii, D. lanceolata, D. oblongifolia, D. rappa, D. sumatrensis.
The axial gum canals distinguish kapur from non-dipterocarps, the arrangement of the axial canals in tangential lines (bands) from Anisoptera, Cotylelobium, Dipterocarpus, Upuna and Vatica. Dryobalanops differs from Shorea (meranti) by the presence of fibre-tracheids, the greater abundance of solitary pores, and the camphor-like odour.
Growth and development
Kapur trees are evergreen, and flowering of trees in certain areas is more or less concurrent. Like most western Malesian dipterocarps, they flower and fruit profusely at irregular intervals, but more frequently than other genera in this area except for Neobalanocarpus. The trees are capable of rapid growth, and girth increments of as much as 12.5 cm per year have been recorded for D. oblongifolia in Peninsular Malaysia. This is, however, exceptional, and under normal conditions the trees have shown a mean annual girth increment of 3.4 cm. They may be expected to attain a diameter of about 65 cm in 60 years, but D. lanceolata has been recorded to grow 1.4 cm in diameter per year over 20 years.
Often the trees start to flower at the age of about 20 years. This is earlier than for most other Dipterocarpaceae but at almost the same age as Anisoptera and Parashorea. The flowers are pollinated by honey bees (Apis spp.). Kapur seeds have been observed to germinate before they are shed. Established seedlings can survive in the shade for a considerable time and can gradually grow through stands of secondary species. Seedlings of D. lanceolata are exceptional among dipterocarps in being highly shade tolerant, yet at the same time respond to full sunlight with height and diameter growth which is faster than any other dipterocarp.
Metamorphosis has been described for D. sumatrensis, i.e. loss of architectural model with the development of many subcrownlets which subsequently develop mutual avoidance.
Other botanical information
The genus Dryobalanops is homogeneous and well-defined. It is closely related to Parashorea. It was recently discovered that D. sumatrensis is the correct name for the well-known species D. aromatica.
Kapur often occurs gregariously as a canopy tree in lowland dipterocarp forest and mixed peat-swamp forest; sometimes also in kerangas (heath forest) vegetation. The trees often grow on hillsides, ridges or near streams, up to 800 m altitude.
Propagation and planting
The seed weight is about 10 g for D. sumatrensis and about 6 g for D. lanceolata. Seeds can only be stored for a short period (up to 16 days) at a temperature of 14°C and moisture content of 30%. Seed collection should begin as soon as the seed wings start to turn brown.
Seeds germinate rapidly: after 1-2 weeks for D. sumatrensis and after 2-3 weeks for D. oblongifolia. Germination in the nursery is usually good and simultaneous. The best response in height increment of first year D. sumatrensis seedlings in a shaded nursery in Malaysia was to 50 mg P2O5 and 300 mg nitrogen (such as ammonium sulphate) per pot, the nitrogen being applied in 3 doses at 2-month intervals. Like all dipterocarps, kapur roots are associated with mycorrhizae, and mycorrhiza infection should be realized for optimal growth of the seedlings. Seedlings at least 30 cm tall from nurseries or from natural regeneration are used for enrichment planting. Saplings of 40-70 cm tall can be cut and used as stump material. When planted in the field, spacing is 3 m × 2 m or 4 m × 3 m. Saplings of D. sumatrensis that were 11 years old, planted in the shade of a 7-year-old stand of Leucaena leucocephala (Lamk) de Wit in East Kalimantan, showed a survival rate of 84% after 4 months.
Silviculture and management
Kapur is suitable for management under the selective logging system. Where kapur trees are abundant, it is not difficult to convert the forest into a practically pure stand in a single rotation. In years when trees fruit abundantly, natural regeneration occurs profusely. Opening of the canopy and removing undesirable species enhances the growth of seedlings. In areas with poor regeneration, enrichment planting of kapur may be practised and the success rate is higher than with other dipterocarps because of the drought tolerance of the seedlings.
Diseases and pests
Brown pinhead spot caused by Colletotrichum gloeosporioides is reported as a leaf disease of D. sumatrensis in Malaysia. Seedlings in nurseries are reported to be susceptible to damage by termites, seedlings in the field to destruction by porcupines. Weevils of the genera Alcidodes and Nanophyes can attack the seeds.
Kapur logs are subject to ambrosia beetle attack after felling, and often the trees are infested by a minute, unidentified borer, a beetle of the family Lymexylonidae, which does not affect the strength of the timber but detracts from its appearance. Neither the beetle nor the borer can survive in seasoned wood and quick extraction of the logs from the felling areas may be important.
Camphor oil can be obtained by tapping the bole. To collect the solid camphor, the tree must be felled.
Measurements of trees in Peninsular Malaysia have shown that trees with a mean diameter of 107 cm have an average timber volume of 18.2 m3. In a 36-year-old plantation with a mean bole diameter of 27.4 cm the timber volume was 263 m3/ha.
Since Dryobalanops species often occur gregariously or semi-gregariously, natural regeneration is usually abundant, even in logged-over forest. Thus, kapur is not very liable to genetic erosion unless the forest is destroyed completely.
Kapur seems very suitable for timber production in sustainably managed forest. As this form of forest management will gain more importance, kapur might be one of the most important timber producers in the near future.
- Afzal-Ata, M., Nur Supardi & Selvaraj, P., 1985. Local volume table for plantation kapur (Dryobalanops aromatica Gaertner f.) at Sungai Puteh forest reserve (Federal Territory). Malaysian Forester 48: 276-287.
- Ashton, P.S., 1982. Dipterocarpaceae. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana. Ser. 1, Vol. 9. Martinus Nijhoff/Dr. W. Junk Publishers, The Hague, Boston, London. pp. 237-552.
- Daljeet-Singh, K., 1974. Seed pests of some dipterocarps. Malaysian Forester 37: 24-36.
- Hallé, F. & Ng, F.S.P., 1981. Crown construction in mature dipterocarp trees. Malaysian Forester 44: 222-233.
- Kostermans, A.J.G.H., 1988. Dryobalanops sumatrensis, comb. nov., the correct name for Dryobalanops aromatica. Blumea 33: 343-346.
- Liew, T.C. & Wong, F.O., 1973. Density, recruitment, mortality and growth of dipterocarp seedlings in virgin and logged-over forests in Sabah. Malaysian Forester 36: 3-15.
- Nurhayadi, R., Durisutanto, F.X. & Sardjono, M.A., 1985. Survival percentage and growth of seedlings of Shorea oleosa (meranti) and Dryobalanops aromatica (kapur) under Leucaena leucocephala (lamtoro gung) shade. German Forestry Group Report, Mulawarman University No 3: 15-18.
- Ser, C.S., 1981. Malaysian timbers - kapur. Malaysian Forest Service Trade Leaflet No 46. Malaysian Timber Industry Board, Kuala Lumpur. 8 pp.
- Sundralingam, P., 1983. Responses of potted seedlings of Dryobalanops aromatica and Dryobalanops oblongifolia to commercial fertilizers. Malaysian Forester 46: 86-92.
- Tang, H.T. & Tamari, C., 1973. Seed description and storage tests of some dipterocarps. Malaysian Forester 36: 113-128.
Selection of species
- H.S. Lee (general part),
- W.C. Wong (properties),
- J. Ilic (wood anatomy),
- M.S.M. Sosef (selection of species)