Palaquium (PROSEA Timbers)

Plant Resources of South-East Asia
Introduction

Protologue: Fl. Filip.: 403 (1837).

Family: Sapotaceae

Chromosome number: x= unknown; P. gutta: 2n= 24

Trade groups

Nyatoh: lightweight to medium-heavy hardwood, e.g. Palaquium amboinense Burck, P. burckii H.J. Lam, P. hexandrum (Griffith) Baillon, P. luzoniense (Fernandez-Villar) S. Vidal, P. maingayi (C.B. Clarke) King & Gamble, P. microphyllum King & Gamble, P. obovatum (Griffith) Engl., P. obtusifolium Burck, P. rostratum (Miq.) Burck, P. xanthochymum (de Vriese) Pierre ex Burck.

Bitis: heavy hardwood, e.g. P. ridleyi King & Gamble, P. stellatum King & Gamble.

Vernacular names

Nyatoh

padang (En)
Indonesia: nyatuh
Malaysia: jangkar (Sarawak)
Papua New Guinea: pencil cedar
Philippines: red nato
Thailand: chik-khao (Chumphon, Surat Thani)
Vietnam: chây.

Bitis

Malaysia: nyatoh batu (Sabah, Sarawak)
Thailand: chik-nom (Ranong, Satun), khanun-nok (Chanthaburi).

Origin and geographic distribution

The genus Palaquium consists of about 110 species and is distributed from western India and Sri Lanka to southern China and east to Polynesia (Samoa). The centre of diversity is western Malesia; most species are found in the Philippines (about 30) and Borneo (about 35), many of them endemic. Peninsular Malaysia and Sumatra are somewhat less rich in species (about 20). New Guinea is considered an important secondary centre of diversity with about 13 species. The most widely distributed species are P. amboinense and P. obtusifolium (western Indonesia to New Guinea), P. obovatum (India to the Philippines and the Moluccas) and P. ridleyi (Indo-China to New Guinea).

Uses

Nyatoh wood is in general suitable for house construction, but not when in contact with the ground. Some Palaquium species may even be used for columns, beams and rafters. Sometimes the trees are used for making canoes. The most important uses of nyatoh are for the manufacture of fine furniture, decorative doors and veneers, and panelling. The wood is also suitable for flooring boards, partitions, household appliances and sometimes for musical instruments, whereas the buttress wood is commonly used for making oars, cartwheels, and handles of hoes and axes.

Bitis, being generally more heavy and more durable than nyatoh, is generally used for heavy construction, heavy-duty flooring, posts, door and window frames, and paving blocks.

Gutta-percha, i.e. latex from Palaquium trees, especially P. gutta, has been praised for its insulating property and imperviousness to water. As such, it has been in demand for the insulation of subterranean and submarine electrical cables. It has also been used in the manufacture of golf balls, certain types of surgical appliances, transmission bells, and acid-resistant receptacles. Other uses have included splints for fractures, supports, pipes, speaking tubes, in telephone receivers, as adhesives and an ingredient of chewing gum. At present its main application is for protecting wounds and in dental clinics, where it is proving to be useful for people allergic to synthetic fillers.

The fruits of several species (e.g. P. burckii, P. eriocalyx H.J. Lam, P. hexandrum, P. lanceolatum, P. macrocarpum, P. philippense, P. rostratum, P. stellatum and P. walsurifolium) are edible. The seeds often contain a fat which is used for cooking or as an illuminant, and is sometimes used for the manufacture of soap and vegetable butter.

Production and international trade

Timber from Palaquium species is usually traded as nyatoh together with the timber of other Sapotaceae genera, particularly Payena, Pouteria and Madhuca. However, in many places Palaquium species supply the bulk of the timber sold as nyatoh. The export of nyatoh sawn timber from Peninsular Malaysia decreased from 16 500 m³ (with a value of US$ 2.1 million) in 1981 to 9500 m³ (with a value of US$ 1.3 million) in 1986. From 1986 onward the export increased to 32 500 m³ with a value of US$ 6.1 million in 1990, but in 1992 it was only 8000 m³ with a value of US$ 2.8 million. Large amounts of nyatoh are also exported from Sarawak and Sabah; the export of round logs from Sabah was 65 000 m³ (worth US$ 6.3 million) in 1987, and in 1992 the export was 14 000 m³ of logs and 8500 m³ of sawn timber with a total value of US$ 4.4 million. In Papua New Guinea nyatoh is ranked in MEP (Minimum Export Price) group 1, and fetched a minimum export price of US$ 100/m³ for saw logs in 1992.

Timbers of the bitis class are usually converted to scantling sizes, and sold unclassified. The bulk of the "seriah" sold in Singapore consists of logs of Palaquium and Payena, and probably other Sapotaceous trees imported from Indonesia.

Some Palaquium species have latex in sufficient amounts to make them commercially important in gutta-percha trade. The best grade of gutta-percha is produced by P. gutta. International trading in gutta-percha, in particular to Europe, started in the second half of the 19th Century with Singapore as the centre. After the trees around Singapore were felled the search for gutta-percha quickly extended northward into Peninsular Malaysia, and south and east into Indonesia, through the Riau Archipelago to Kalimantan, to Sarawak and Sabah and ultimately to the Philippines. Export of Indonesian gutta-percha is mainly to Singapore (93%) and to a much lesser extent to the United States, Germany, Britain and Hong Kong. The total gutta-percha potential of Indonesia is estimated at 10 000 t/year, most of it present in Kalimantan (38%), South Sumatra (23%) and South Sulawesi (23%). However, trade in gutta-percha has decreased drastically due to the replacement by synthetic plastics.

Properties

A general description of nyatoh and bitis is given here. Palaquium timber with its density of (400-)450-1120 kg/m³ at 15% moisture content is classified in both groups, depending on the weight of the timber; the arbitrary limit between the groups lies at 850 kg/m³.

Nyatoh is a light to medium-weight, moderately hard to hard red meranti-like wood. The heartwood is pinkish-brown to reddish-brown and only moderately distinct from the lighter sapwood. The density is (420-)550-800(-850) kg/m³ at 15% moisture content; that of the majority of the commercial supply is 600-700 kg/m³. The grain is shallowly interlocked, texture moderately fine and even.

At 15% moisture content the modulus of rupture is 70-130 N/mm², modulus of elasticity 10 000-18 000 N/mm², compression parallel to grain 28-54 N/mm², compression perpendicular to grain 2.5-7 N/mm², shear 8.5-11(-17) N/mm², cleavage 39-77 N/mm radial and 49-87 N/mm tangential, Janka side hardness 3700-7000 N and Janka end hardness 3900-7600 N.

The recorded rates of shrinkage of nyatoh are moderate, from green to 15% moisture content 1.3-3% radial and 2.3-4% tangential, from green to oven dry about 4.1% radial and 7.6% tangential. Air drying of 40 mm thick boards takes approximately 4 months, 25 mm thick boards about 2 months. The timber can be satisfactorily dried by using kiln schedule E (Malaysia). Form stability is medium to good when dry.

The sawing properties are variable, probably depending on the species; but variation may be large within species too. Some nyatoh-producing species contain silica, which makes the timber difficult to work (e.g. P. gutta and P. walsurifolium). Gum may clog cutters. Nyatoh is easy to polish when the grain is properly filled. The wood is easy to turn. Pre-boring for nails and screws is advised because of easy splitting. Gluing is trouble-free. The fine grain and colour make it suitable for veneer; it can be peeled at a 91° peeling angle without pretreatment. Sometimes the wood is figured and then the veneer can be very attractive, especially when radially sliced. Peeling is reported as easy to fairly difficult, and a good plywood can be made from the timber. The logs are reasonably free from defects.

Nyatoh is rated as only moderately durable. It is prone to termite attack and susceptible to fungal attack, but not to powder-post beetles. Treated nyatoh timber can be very durable. However, it is very resistant to preservative treatment. Using the open tank method and an equal mixture of creosote and diesel, the heartwood absorbs on average only about 11 kg/m³. Bitis comprises heavier timber, with density of 850-1150 kg/m³ at 15% moisture content. The heartwood is reddish-brown to dark brown, and clearly differentiated from the lighter sapwood. The grain is fairly straight, texture moderately fine and even. Bitis is very hard and strong, and much more durable than nyatoh.

At 15% moisture content the modulus of rupture is 105-170 N/mm², modulus of elasticity 10 000-23 800 N/mm², compression parallel to grain 65-90 N/mm², compression perpendicular to grain 9-12.5 N/mm², shear 10-17 N/mm², cleavage c. 86 N/mm radial and 67 N/mm tangential, and Janka side hardness 14 400-14 900 N.

Bitis is difficult to dry; shrinkage rates are rather high (from green to 15% moisture content 3.0% radial and 4.0% tangential), and there is a tendency to surface checking. A mild kiln schedule (B in Malaysia) should be used.

Bitis is difficult to work, rapidly blunting saws and cutters due to the presence of silica, but it produces a smooth surface in planing and takes stain and polish satisfactorily. The timber tends to split in boring and mortising. Bitis is not suitable for veneer and plywood because it is difficult to peel.

Bitis timber is rated as durable and is resistant to termite attack, but it is very difficult to impregnate.

Freshly felled wood often has a sour smell and a bitter taste. It lathers freely when rubbed with water. Dust from sawn nyatoh and bitis timber may cause irritation to skin and mucous membranes.

Wood of P. microphyllum contains 52% cellulose, 22% lignin, 17% pentosan, 1.0% ash and 0.05% silica. The solubility is 3.2% in alcohol-benzene, 1.4% in cold water, 5.4% in hot water and 14.8% in a 1% NaOH solution. The energy value of the wood is 20 430 kJ/kg.

Gutta-percha is a non-elastic rubber derived from the latex. The fresh greyish-white latex turns reddish-brown when exposed to the air. It is then a marble-like solid mass. In contrast, pure gutta-percha is colourless and translucent when sliced thinly. At 25° C it becomes pliable and it gradually softens upon heating. At 60° C, it is so plastic that it can be drawn into threads of any form. The hardest gutta-percha will soften at 65° C. Insoluble in cold water, gutta-percha dissolves easily in benzene, carbon disulphide, chloroform and all solvents of rubber. Concentrated alkalies, dilute acids and even hydrofluoric acid do not affect the composition of gutta-percha. P. gutta gives the best quality of gutta-percha, containing up to 80% poly-isoprene and then only 20% resin. Many other Sapotaceae trees may also provide gutta-percha, but the proportion of poly-isoprene and resin is usually much less favourable.

Description

Small to very large trees, with latex, sometimes up to 60 m tall, usually with columnar buttressed bole up to 130(-250) cm in diameter, often branchless for a considerable length; outer bark smooth, cracked or fissured, usually brown to reddish-brown, inner bark soft and fibrous, pinkish-yellow, pink, red or reddish-brown; twigs usually slender (but massive in P. clarkeanum), often hairy or scurfy at least at tips, often with distinctly developed terminal cone-like buds.
Leaves arranged spirally, usually densely to loosely clustered at ends of twigs, simple and entire, usually obovate, generally glabrous above and more or less hairy beneath when mature; secondary veins straight, curving towards apex and often joined near leaf margin, tertiary veins transverse or parallel to secondary ones or reticulate; petiole usually of even thickness throughout its length; stipules small to large, usually early caducous, rarely absent.
Inflorescence an axillary or rarely terminal fascicle, 1-many-flowered.
Flowers bisexual or rarely unisexual; sepals (4-)6(-7), generally in two whorls of 3, ovate or triangular; corolla (5-)6-lobed, with usually short tube and imbricate, often contort lobes, white to yellowish or greenish; stamens (10-)12-18(-36), inserted at the throat of the corolla tube, with acute anthers; pistil 1, with (5-)6(-10)-celled ovary and usually long style.
Fruit a berry with fleshy pericarp, 1-3-seeded.
Seed with a crustaceous to coriaceous testa and a large hilum often covering up to two-thirds of the surface of the seed, rarely hilum narrow (e.g. P. ridleyi, P. stellatum); endosperm usually absent and cotyledons thick and fleshy, but rarely endosperm abundant and cotyledons thin (e.g. P. ridleyi).
Seedling usually with epigeal germination (sometimes hypogeal, e.g. P. gutta and P. obovatum), with strongly developed taproot; first pair of leaves opposite or subopposite, subsequent leaves arranged spirally and soon similar to leaves of adult trees.

Wood anatomy

Macroscopic characters

Heartwood deep pink, red, red-brown or purple-brown, sometimes with dark streaks, distinctly to indistinctly demarcated from the pale red sapwood, sometimes with a sour smell when freshly sawn.
Grain shallowly to moderately interlocked, sometimes wavy.
Texture moderately fine to coarse; wood dull, sometimes glossy.
Growth rings indistinct to vaguely visible; vessels and parenchyma indistinct to barely visible to the naked eye; rays and parenchyma not distinct without a lens.

Microscopic characters

Growth rings indistinct, if present marked by differences in spacing of tangential parenchyma bands, and/or in fibre wall thickness on either side of the ring boundary.
Vessels diffuse, 6-14/mm², mainly in radial multiples of 2-5(-8), sometimes in a radial or radial to oblique pattern, round to oval, average tangential diameter 100-220μm; perforations simple; intervessel pits alternate, round, (4-)6-8μm; vessel-ray pits mainly confined to the upright and square cells, mostly large and simple, horizontally to vertically elongated or round, partly half-bordered, scarce in procumbent cells; helical thickenings absent; gum-like deposits and thin-walled tyloses sometimes present.
Fibres generally 1000-2100μm long, non-septate, mostly medium thick-walled, but ranging from very thin- to very thick-walled, with simple to minutely bordered pits mainly confined to the radial walls.
Parenchyma abundant, diffuse, diffuse-in-aggregates or in fine discontinuous to continuous 1-2(-3)-seriate straight to slightly wavy bands forming a reticulate pattern, 4-8 lines per radial mm, in 6-8(-10)-celled strands.
Rays 8-12(-15)/mm, 1-2(-3)-seriate with uniseriate tails, in some species mainly uniseriate, in others mainly multiseriate, up to 900μm high, heterocellular with (1-)2-5(-8) rows of upright and square marginal cells and procumbent body cells.
In some species crystals recorded in chambered axial parenchyma in chains of up to 8 cells.
Silica bodies present in ray cells of most species.

Species studied: P. amboinense, P. ellipticum (Dalzell) Baillon, P. gutta, P. hexandrum, P. leiocarpum, P. lobbianum, P. luzoniense, P. maingayi, P. microphyllum, P. obovatum, P. obtusifolium, P. polyanthum (Wallich) Baillon, P. ridleyi, P. rostratum, P. semaram, P. stellatum, P. walsurifolium, P. xanthochymu.

Growth and development

The few data available show a slow rate of growth. In Peninsular Malaysia the mean annual girth increment for P. maingayi and P. rostratum is only 1.5 cm and 1.8 cm, respectively; these trees take 100 and 70 years respectively, to attain a diameter of 55 cm. However, a P. rostratum tree in an arboretum attained a diameter of 57 cm in 40 years. P. gutta has a mean annual girth increment of 3.8 cm and attains about 8 m height in 7 years, 17 m in 23 years and a diameter of about 50 cm in 50 years.

There is usually good natural regeneration, but seedlings are often choked out or retarded in growth by other trees and brush. Fruit is borne abundantly some years, but little of it survives. In many cases flowers do not reach maturity because of attack by insects or because of unfavourable weather conditions. Flowers may remain closed for a long time (up to 18 months), probably waiting for favourable weather conditions for opening. There seems to be no definite and regular periodicity of flowering and fruiting seasons. There are however, certain years, when there is a rather general and heavy seed crop. The ripe fruit is greedily eaten by fruit bats; but not the seeds. There are often large numbers of ripe seeds on the ground underneath bat roosts. Fallen fruits are quickly consumed by squirrels, birds, insects and other animals. Only a small proportion of the seeds thus survives and few seeds have a chance to germinate.

Other botanical information

Palaquium is distinguished from other Sapotaceae genera by its flowers having most commonly 6 sepals (two whorls of 3) and 12 stamens. The leaves show much variation between the different species in shape, size, indumentum and venation. A subdivision of the genus (into subgenera or sections) is not warranted as no discrete groups can be recognized, probably because the species show reticulate relationships.

Ecology

Most Palaquium species grow in lowland forest. Only occasionally are species found at higher elevations, e.g. P. regina-montium in Peninsular Malaysia and P. rioense in Borneo. Usually the trees occur scattered in the forest; rarely Palaquium species form almost pure stands, e.g. P. xanthochymum locally in Peninsular Malaysia. Many species are common in freshwater swamp forests, some grow commonly in peat swamps, e.g. P. ridleyi and P. maingayi.

Propagation and planting

Carefully selected seeds will show a germination rate of 75-85% or more. Palaquium can also be grown from cuttings and marcots, but the percentage of success is not high. It is also possible to propagate the tree by layering and by cleavage, but these methods are less successful than the planting of seedlings. Nursery seedlings can be planted in the field when about 20 cm tall. In agroforestry systems, spacing may be 3 m × 2 m.

A plantation of gutta-percha trees was started in the early 1930s on a commercial basis at Cipetir, West Java. The total area of gutta-percha plantations in Indonesia may comprise 4000 ha.

Silviculture and management

Natural regeneration of Palaquium trees is often plentiful in secondary or logged-over forests. The enrichment planting system ensures sufficient regeneration in natural forests, but the saplings are often poorly competitive. Palaquium trees need a considerable amount of light for optimal development. Trees freed by cutting away the overshadowing vegetation show much increased vigour.

Forest with a fair amount of natural regeneration of Palaquium can be gradually changed over to an almost pure forest by gradually removing other species.

Diseases and pests

Palaquium trees are susceptible to the fungus jamur upas (Corticium salmonicolor).

Harvesting

In timber concession areas in the Riau Archipelago and Sumatra, suntai (Palaquium burckii) is placed in the same timber group as meranti (Shorea spp.), punah (Tetramerista glabra Miq.) and pulai (Alstonia spp.).

At 60° C, gutta-percha can be moulded into a desired shape, which is retained on cooling. Gutta-percha is usually transported and traded in vacuum zinc containers.

Genetic resources

The gutta-percha plantations in Indonesia are also maintained to secure the supply of seed for future planting.

Prospects

Nyatoh has become more important since 1985; trade and export of this timber have been increasing. This is due to intensified logging operations and to the wood properties which are close to meranti, for which there is an increasing demand. More research into silvicultural aspects is urgently needed. It is not known how the timber properties, which vary greatly, correspond to the botanical species, and hence, silviculturists do not know which species they should concentrate on. Clarification of this matter is urgently needed.

Literature

Abidin, E.Z., 1974. Getah perca Indonesia dewasa ini [Indonesian gutta-percha at present]. Kehutanan Indonesia, July 1974: 320-322.
Burgess, P.F., 1966. Timbers of Sabah. Sabah Forest Records No 6. Forest Department, Sabah, Sandakan. pp. 447-455.
Jafarsidik, Y., 1987. Pengenalan anakan jenis kayu perdagangan di daerah hutan Sijunjung, Sumatra Barat [Description of commercial tree seedlings at Sijunjung forest area, West Sumatra]. Bulletin Penelitian Hutan No 493: 21-43.
Martawijaya, A., Kartasujana, I., Kadir, K. & Prawira, S.A., 1986. Indonesian wood atlas. Vol. 1. Forest Products Research and Development Centre, Bogor. pp. 102-106.
Meniado, J.A., 1980. About the wood nato. Forpride Digest 9(1): 19-34.
Meniado, J.A., Tamolang, F.N., Lopez, F.R., America, W.M. & Alonzo, D.S., 1975. Wood identification handbook for Philippine timbers. Vol. 1. Government Printing Office, Manila. pp. 312-321.
Ng, F.S.P., 1972. Sapotaceae. In: Whitmore, T.C. (Editor): Tree flora of Malaya. A manual for foresters. Vol. 1. Longman Malaysia SDN Berhad, Kuala Lumpur. pp. 388-439.
Reyes, L.J., 1938. Philippine woods. Technical Bulletin No 7. Commonwealth of the Philippines, Department of Agriculture and Commerce, Bureau of Printing, Manila. pp. 396-400.
van Royen, P., 1960. Revision of the Sapotaceae of the Malaysian area in a wider sense 23. Palaquium Blanco. Blumea 10: 432-606.
Wong, T.M., 1981. Malaysian timbers - nyatoh. Malaysian Forest Service Trade Leaflet No 54. Malaysian Timber Industry Board, Kuala Lumpur. 12 pp.

Authors

J. Kartasubrata (general part),
N. Tonanon (properties),
R.H.M.J. Lemmens (properties, selection of species),
R. Klaassen (wood anatomy)