Shorea (yellow meranti) (PROSEA)

Plant Resources of South-East Asia
Introduction

Shorea Roxb. ex Gaertner f. (yellow meranti)

Protologue: Fruct. 3: 47 (1805).

Family: Dipterocarpaceae

Chromosome number: x= 7; S. multiflora: 2n= 14

Trade groups

Yellow meranti: lightweight hardwood, e.g. Shorea balanocarpoides Sym., S. faguetiana Heim, S. gibbosa Brandis, S. longisperma Roxb., S. polyandra P. Ashton.

Vernacular names

Yellow meranti

Brunei: selangan kacha
Indonesia: meranti kuning (general), damar hitam (Sumatra), damar kelepek (Kalimantan)
Malaysia: meranti damar hitam (Peninsular), yellow seraya (Sabah), lun kuning (Sarawak)
Philippines: yellow lauan, manggasinoro (both also including white meranti), lun
Thailand: kalo (Yala, Narathiwat).

Origin and geographic distribution

Shorea consists of about 194 species, 163 of which occur in Malesia. The genus is distributed from Sri Lanka and India through Indo-China towards Malesia. Within Malesia the species occur eastward to the Moluccas. The genus is absent from the Lesser Sunda Islands but fossil wood has been recorded for Timor. Yellow meranti is not found outside Malesia except for the southernmost part of Thailand. The greatest diversity of the 33 species belonging to the yellow meranti group is found in Borneo (29 species), followed by Peninsular Malaysia (10 species), Sumatra (8 species) and the Philippines (1 species).

Uses

Shorea is economically the most important timber genus in the Asian humid tropics.

Yellow meranti is used for light constructional work. The sapwood should be excluded in any application or treated suitably, because it is extremely susceptible to powder-post beetle attack. The heartwood is used for a wide range of purposes such as light traffic flooring, door and window frames, planking, ceiling, interior trim, utility furniture and cabinet work, toys, turnery, boxes, and ship and boat building. Generally it is an excellent timber for joinery. It is often used locally when a good firmness is required. The wood is not very durable and therefore application in contact with the ground should be avoided. Yellow meranti is an excellent timber for plywood, both as face and core veneer. The wood is also very suitable for the manufacture of hardboard and particle board, and is used with good results as pulp for making paper.

The species of yellow meranti produce a very dark, almost black dammar which is the darkest among dipterocarps. It is, however, of low grade but is sometimes used for torches. In former days the resin of some species was used for blackening teeth when this was a fashion. The bark of some species can be stripped and used to furnish house walls or it can be made into baskets and bins. Fruits are sometimes collected as "illipe nuts"; they yield a fat which is used in cooking and for other purposes.

Production and international trade

For Indonesia only export figures for meranti as a whole are available. The export of sawn meranti timber from Indonesia increased slightly from 1.3 million m³ (with a value of US$ 249 million) in 1987, to 1.4 million m³ (with a value of US$ 301 million) in 1989. Much more important in Indonesia is the production and export of plywood (estimated export value in 1990: US$ 3000 million), in which yellow meranti wood contributes a fairly important part, together with red meranti (which contributes the major part), keruing (Dipterocarpus spp.) and white meranti.

Yellow meranti is not an important export timber in Peninsular Malaysia. In 1981 the export of sawn yellow meranti was 13 000 m³ (with a value of US$ 1.0 million) but it declined rapidly. In 1983 the export of sawlogs was 2000 m³ (worth US$ 90 000). From then on, no export figures of yellow meranti as a separate trade group are available, but some yellow meranti is probably traded as "mixed light hardwood". In Sabah and Sarawak, yellow meranti ("yellow seraya") is much more important. In 1987 the export of round logs from Sabah was 890 000 m³ (with a value of US$ 89 million), and in 1992 the export of logs was 170 000 m³ and that of sawn timber 202 000 m³ with a total value of US$ 67 million. No export statistics are available from other countries.

Properties

Yellow meranti is a lightweight hardwood. The heartwood is light yellowish-brown, often with a greenish tinge, light brown with a yellowish tinge on exposure. The sapwood is moderately to clearly distinct from the heartwood, and is paler, often more yellow, but it becomes less distinct on exposure. The planed surface is without lustre, and a faint stripe figure is visible on the radial surface. The density is variable, (370-)480-675(-860) kg/m³ at 15% moisture content. The grain of the wood is generally interlocked, texture moderately coarse to moderately fine (finer than other merantis) and even.

At 15% moisture content the modulus of rupture is 67-102 N/mm², modulus of elasticity 10 000-12 650 N/mm², compression parallel to grain 40-51 N/mm², compression perpendicular to grain 4-5 N/mm², shear 8-11 N/mm², cleavage 48-60 N/mm radial and 50-65 N/mm tangential, Janka side hardness 3290-3850 and Janka end hardness c. 4300 N.

The rates of shrinkage are fairly low to moderate, from green to 15% moisture content 0.9-1.2% radial and 3.1-3.8% tangential, and from green to 12% moisture content 2.2-2.5% radial and 6.5-7.5% tangential. Yellow meranti dries fast to moderately slowly and with few defects. The air drying of 15 mm and 40 mm thick boards takes about 3 months and 5 months, respectively. In Malaysia kiln-drying schedule J is recommended. Usually the timber dries well without any serious degrade, but the drying of boards over 50 mm thick is more difficult.

Yellow meranti is easy to resaw, cross cut, plane, bore and turn. The planed surface is generally smooth, but bored surfaces of air-dried timber are rough and turned surfaces slightly rough, probably because of the presence of interlocked grain. In general, yellow meranti has better working properties than white meranti (largely owing to the absence of silica), although there is some difference between species, depending on the density of the wood. The nailing characteristics are rated as poor to satisfactory. It is recommended to fill the pores before painting or varnishing. Yellow meranti can be peeled satisfactorily if the logs are free from defects such as knots, brittle heart or decay. Dried veneer is almost flat and the gluing properties are rated as good. The veneer is suitable for face and core veneer. Gluing with urea-formaldehyde produces plywood which meets the German standard. Particle board of density above 610 kg/m³ and made with 8% resin and 1% wax can meet the requirements stipulated in the British standard.

Yellow meranti is not a durable timber. Graveyard tests conducted in Malaysia indicated an average service life of stakes in contact with the ground of 1.9 years for S. multiflora and only 1.1 years for S. longisperma. In temperate regions the average service life in contact with the ground is moderate, 10-15 years. The timber is susceptible to attack by dry-wood termites, and slightly susceptible to pinhole borers, but pinholes are less common than in other merantis. In general, yellow meranti is very difficult to treat with preservatives. Using an equal mixture of creosote and diesel fuel in the open tank treatment, the average absorption for S. longisperma wood is only 42 kg/m³ and for wood of S. multiflora even less, 19 kg/m³. The full-cell pressure treatment with copper-chrome-arsenic gives an average absorption of 180 kg/m³ at a solution strength of 3%.

Wood of S. gibbosa contains 52% cellulose, 29% lignin, 16% pentosan, 1% ash and no silica. The solubility is 6.3% in alcohol-benzene, 0.8% in cold water, 3.2% in hot water and 14.1% in a 1% NaOH solution. The energy value is 18 400 kJ/kg.

Description

Medium-sized to very large trees up to 60(-75) m tall; bole straight, cylindrical, branchless for up to 35(-45) m and with a diameter of up to 150(-300) cm; buttresses prominent, up to 4(-6.5) m high; bark surface usually appearing scaly, grey or light brown, outer bark fairly thin, chocolate brown, inner bark dull yellowish-brown, exuding a dark brown or blackish resin; mature crown hemispherical or dome-shaped, sympodial.
Leaves alternate, simple, entire, glabrous, pinnately veined with scalariform tertiary venation, often glaucous on the lower surface; stipules minute, fugacious. Inflorescence terminal or axillary, paniculate, bracts minute.
Flowers secund or distichous, bisexual, 5-merous, actinomorphic, scented; calyx lobes free, hirsute; petals narrow, connate at base, bright to pale yellow, the outer surface hirsute; stamens usually 15, the anthers with 2 pollen sacs, broadly oblong to subglobose, the prominent appendages scabrous towards the apex; ovary usually surmounted by a stylopodium, tomentose, style shorter than the ovary.
Fruit usually shortly stalked with the calyx lobes subequal or the outer 3 much elongated, these more or less thickened and saccate at base; nut 1-seeded, free from the calyx, subglobose to ovate, sharply pointed.
Seedling with epigeal germination; pericarp splitting irregularly; cotyledons pale yellow or reddish; first two leaves opposite, subsequent leaves arranged spirally, often larger than those on mature trees.

Wood anatomy

Macroscopic characters

Heartwood pale yellow or light yellowish-brown, often with a greenish tinge, darkening with age, often to light brown with a yellowish tinge; sapwood moderately to clearly distinct from the heartwood, lighter in colour, and in logs often demarcated by staining and dark dammar exudation.
Grain usually interlocked but not very deeply so, sometimes wavy.
Texture moderately coarse or moderately fine and even; figure inconspicuous, but mottled ray figure occurring on quarter-sawn faces and also a faint ribbon figure occurs due to the interlocked grain.
Freshly cut wood smells strongly of tannin.
Growth rings indistinct or absent; vessels rather few to moderately numerous, visible to the naked eye, mostly open; parenchyma rather sparse to moderately abundant, fairly distinct, forming dull yellow borders around the pores similar to white meranti but less markedly aliform; rays rather few, dull yellow, visible to the naked eye.
Ripple marks usually absent or indistinct to the naked eye.
Intercellular canals in more or less long concentric lines on transverse surfaces, usually considerably smaller than the vessels and not visible to the naked eye (but sometimes as large as or larger than the vessels, e.g. in S. balanocarpoides, S. faguetiana and S. xanthophylla), filled with white or yellowish-white contents.

Microscopic characters

Growth rings indistinct or absent.
Vessels diffuse, (2-)6-8(-18)/mm², predominantly solitary but occasionally in radial or oblique groups of 2-3, rarely in clusters of 4 (S. xanthophylla), round to slightly oval, (80-)200-250(-300) μm in tangential diameter; perforation plates simple; intervessel pits alternate, vestured, 2.5 μm; vessel-ray pits and vessel-parenchyma pits large (over 10 μm in diameter), round and gash-like; tyloses absent or sparse.
Fibres on average 1150 μm long, non-septate, thin- to moderately thin-walled, sometimes moderately thick-walled, with simple to minutely bordered pits mainly confined to the radial walls.
Parenchyma predominantly paratracheal, consisting of mostly complete or incomplete sheaths to the vessels, in some specimens distinctly aliform and confluent (especially around vertical resin canals, e.g. in S. hopeifolia); apotracheal parenchyma enclosing the vertical resin canals and occasionally occurring as short fine lines; diffuse parenchyma infrequent.
Rays 4-9(-12)/mm, commonly multiseriate (3-10-seriate, mostly 3-5-seriate), uniseriate rays sometimes present, 15-140 μm wide, 280-4000 μm high, in most species Kribs type heterogeneous II and III mixed; sheath cells present in S. faguetiana, absent in other species.
Prismatic crystals present in some axial parenchyma cells and ray cells.
Silica bodies absent.
Radial intercellular canals present, quite fine.
Axial canals mostly arranged in long tangential series or lines (but usually shorter than in red meranti); sometimes diffuse canals present, with white contents.

Species studied: S. acuminatissima, S. balanocarpoides, S. faguetiana, S. gibbosa, S. hopeifolia, S. multiflora, S. xanthophylla.

In addition to the wood colour and lack of lustre, yellow meranti differs from white meranti in the presence of radial intercellular canals and the absence of silica.

Growth and development

The growth rates differ considerably between species: S. maxima trees can reach a diameter of 37 cm at an age of 40 years and S. multiflora 41 cm, whereas S. balanocarpoides and S. longisperma grow faster and can reach a diameter of 54 cm and 57 cm, respectively, in 40 years. Experiments in Malaysia showed that S. maxima and S. multiflora are probably self-incompatible.

Other botanical information

Anatomical features of the wood and bark provide useful evidence for the classification of species at infrageneric level. The division of the genus Shorea into 4 major timber groups (balau, red meranti, white meranti and yellow meranti) coincides in broad outline with the division of the genus into botanical sections. Timbers of the yellow meranti group belong to the section Richetioides Heim.

Ecology

Shorea species are confined to tropical humid climates with an average annual rainfall exceeding 1600 mm and with less than 6 dry months. Most species occur below 1000 m altitude. The largest numbers of species and of individuals are found on deep, well-drained yellow or red soils in the lowland. Yellow meranti is confined to the aseasonal wet forests, below 1400 m altitude.

Propagation and planting

Seeds rapidly lose their viability. Usually the germination rate of fresh seeds is 80-90% but viability is lost within about 12 days. Fresh seeds of S. maxima have a germination rate of 95% and they can be stored for 14 days at temperatures of 4-14 °C maintaining more than 50% germination. Seeds of other species (e.g. S. faguetiana, S. hopeifolia, S. longisperma and S. multiflora) can survive at 4 °C for about one month; however, chilling injury slowly develops and finally kills the seeds. As in other merantis, stem cuttings can probably be used for propagation, but no experiments on methods of vegetative propagation have been conducted on yellow meranti. When planted into the forest the usual planting distance is 3 m × 3 m.

Silviculture and management

Natural regeneration of yellow meranti may be abundant. For instance, seedlings of S. polyandra may dominate the regeneration in primary and undisturbed forest in South Kalimantan, together with those of Eusideroxylon zwageri Teijsm. & Binnend. In logged-over forest, regeneration of S. polyandra is much less; the most commonly occurring seedlings in such forests belong to Dipterocarpus cornutus Dyer and Sindora leiocarpa Backer ex K. Heyne. This means that enrichment planting with yellow meranti seedlings may be necessary in logged-over forest to ensure an acceptable yield of yellow meranti in the future.

Locally, the density of S. gibbosa trees in East Kalimantan has been established at 0.6 trees/ha.

Diseases and pests

Many animals such as wild boars, squirrels and various kinds of insects feed on seeds and young plants. The beetle Alcidodes dipterocarpi has been reported to cause serious damage to seeds of S. faguetiana.

Harvesting

Yellow meranti logs usually float in water and can be transported by river. In mixed dipterocarp forest in Indonesia, trees over 50 cm in diameter are harvested, leaving at least 25 healthy trees/ha of 20-49 cm in diameter for future cuts.

Genetic resources

Just as in other meranti trade groups, yellow meranti includes common and widely distributed species (e.g. S. balanocarpoides, S. faguetiana, S. multiflora) as well as species which occur only locally or scattered (e.g. S. longiflora, S. maxima). This may easily lead to endangerment of species if large-scale logging without distinction at species level is practised.

Prospects

By comparison with red meranti and white meranti, not much is known about the propagation, planting and silviculture of yellow meranti. Some species grow fairly fast and their timber is of good quality, which seems a justification for more research on propagation techniques and silvicultural aspects.

Literature

Ashton, P.S., 1964. Manual of the dipterocarp trees of Brunei State. Oxford University Press, London. pp. 148-160.
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.
Browne, F.G., 1955. Forest trees of Sarawak and Brunei and their products. Government Printing Office, Kuching. pp. 159-164.
Burgess, P.F., 1966. Timbers of Sabah. Sabah Forest Records No 6. Forest Department, Sabah, Sandakan. pp. 217-226.
Choo, K.T. & Lim, S.C., 1988. Malaysian timbers - yellow meranti. Timber Trade Leaflet No 107. Malaysian Timber Industry Board, Forest Research Institute Malaysia. 8 pp.
Martawijaya, A., Kartasujana, I., Kadir, K. & Prawira, S.A., 1986. Indonesian wood atlas. Vol. 1. Forest Products Research and Development Centre, Bogor. pp. 77-81.
Ng, F.S.P. & Tang, H.T., 1974. Comparative growth rates of Malaysian trees. Malaysian Forester 37: 2-23.
Sasaki, S., 1980. Storage and germination of dipterocarp seeds. Malaysian Forester 43: 290-308.
Sutomo, S. & Pratiwi, 1988. Composition and stocking of natural regeneration in a virgin and logged-over forest in Kintap, South Kalimantan, Indonesia. Buletin Penelitian Hutan No 501: 1-12.
Yap, S.K., 1981. Collection, germination and storage of dipterocarp seeds. Malaysian Forester 44: 281-300.

Selection of species

Authors

K.M. Kochummen (general part),
W.C. Wong (properties),
J.M. Fundter (wood anatomy),
M.S.M. Sosef (selection of species)