Vatica (PROSEA)

Plant Resources of South-East Asia
Introduction

Protologue: Mant. pl. 2: 152 (1771).

Family: Dipterocarpaceae

Chromosome number: x= 11; V. odorata, V. pauciflora, V. rassak, V. stapfiana: 2n= 22

Trade groups

Resak: medium-weight to heavy hardwood, e.g. Vatica maingayi Dyer, V. mangachapoi Blanco, V. oblongifolia Hook.f., V. odorata (Griffith) Sym., V. rassak (Korth.) Blume.

Resak often includes timber of the genus Cotylelobium and sometimes also that of Upuna. The timber of some Vatica species (e.g. V. flavovirens, V. teysmanniana) is traded in Indonesia under the name "giam", which may cause confusion because this is the trade name for the heavy wood of Hopea spp.

Vernacular names

Resak

Papua New Guinea: vatica
Philippines: narig
Cambodia: chrama:hs
Thailand: tamsao (peninsular), phancham (central), yang-nu (Phrae)
Vietnam: làu táu.

Origin and geographic distribution

Vatica, consisting of about 80 species, occurs from eastern and southern India, Sri Lanka and Burma, through Thailand and Indo-China, to southern China (Hainan) and Malesia. It is found throughout Malesia, except for the Lesser Sunda Islands.

In the Malesian region, Borneo is richest in species (about 35, 23 endemic), followed by Peninsular Malaysia (21), Sumatra (11) and the Philippines (7). Towards the east (the Moluccas, New Guinea) only a single species occurs, V. rassak, which is the most widespread, occurring westwards up to Borneo and northwards up to the southern Philippines.

Uses

Resak is used for piling (also in contact with the ground or water), construction of houses (beams, posts, rafters, boards, door and window frames) and ships (keels, ribs), flooring, turnery, cabinet making, and railway sleepers. Less heavy resak timber is also used for furniture, package and pallets and as a substitute for keruing (Dipterocarpus spp.), e.g. in Japan. Although resak is a fairly hard and durable timber, its uses are restricted because of the often comparatively small size of the trees.

The resin is occasionally used for caulking boats and for illumination ("damar rasak"). The bark was formerly used to prevent frothing while boiling the sap of the sugar palm for sugar manufacture, and to arrest fermentation of toddy.

Production and international trade

No statistics are available on the total trade and export of resak, but most of the timber is traded from Borneo, particularly Sarawak and Sabah. Resak is exported on a comparatively small scale, especially to Japan. In 1987, the export of round logs from Sabah was only 1400 m³ with a value of US$ 83 000, but in 1992 it was 13 000 m³ of logs and 600 m³ of sawn timber with a total value of US$ 2.4 million. Commercially, resak from Vatica is among the least important timbers of the dipterocarps, mainly because the trees are often small, and occur scattered; moreover, the logs are sinkers, which hampers transport. However, resak is in demand for local house construction. It is often traded together with timber from Cotylelobium spp.

Properties

Resak is a medium-weight to heavy and hard timber. The heartwood is reddish-brown to brown with a green tinge, darkening on exposure to dark reddish-brown. The sapwood is light yellowish-brown and clearly differentiated from the heartwood in fresh logs, but less sharply defined when dry. The density is 490-1155(-1220) kg/m³ at 15% moisture content. The grain is straight or only slightly interlocked, texture fine and even.

Tested at green condition, the modulus of rupture is 56-105 N/mm², modulus of elasticity 10 200-18 100 N/mm², compression parallel to grain 29-61 N/mm², compression perpendicular to grain 5-12 N/mm², shear 4-13 N/mm², cleavage 44-61 N/mm radial and 52-105 N/mm tangential, and Janka side hardness 2570-8990 N.

The rates of shrinkage are moderate to large, from green to 12% moisture content 1.4-2.2% radial and 3.4-5.4% tangential, from green to oven dry 3.3-4.8% radial and 5.0-9.6% tangential. Resak is moderately slow in drying. Thicker tangential boards tend to cup badly because of the great difference between tangential and radial shrinkage values. Surface checking and splitting can be common on tangential surfaces. It takes about 3 months to air dry 15 mm thick boards, and about 5 months to dry 40 mm thick boards from green to air-dry condition. Seasoning stacks should be weighted and stickers closely spaced. Being a hard and heavy timber, resak needs to be dried very slowly to avoid surface checking. Kiln-drying schedule B (Malaysia) is recommended. Preliminary air drying to below 30% moisture content is advisable.

Resak is rather difficult to saw because of the presence of a large amount of gummy resin which may clog sawteeth. The presence of this resin may also interfere with the planing of the timber, although the final finish may be smooth. Boring is easy and has a smooth finish, turning is slightly difficult. In general, resak timber is hard to peel but it has been reported as being suitable for sliced veneer.

Resak is usually classified as moderately durable to very durable. Wood of V. cuspidata has an average service life in contact with the ground of 14 years under normal Malaysian conditions. Graveyard tests in Indonesia showed that wood of V. teysmanniana had an average service life in contact with the ground of 10 years, but wood of V. rassak only 2 years. Resak is not considered resistant to marine borer attack. The heartwood of the heavier resak timber is not very susceptible to powder-post beetles and very resistant to termite attack, but is less resistant to pinhole borer attack. However, wood of V. rassak may have poor resistance to dry-wood termites. Resak is generally regarded as being very difficult to treat with preservatives, but for most applications, treatment is not required.

Wood of V. rassak contains 45% cellulose, 12% pentosan, 0.3% ash and up to 0.1% silica. The solubility is 1.6% in cold water, 3.6% in hot water and 12.2% in a 1% NaOH solution. The energy value is 20 200 kJ/kg.

The resin from the wood and bark ("damar rasak", particularly from V. rassak) is light yellow to light brown, and coagulates to a semi-transparent and brittle, yellow, brown or reddish solid mass.

Description

Small to medium-sized trees, rarely fairly large, up to 40 m tall with frequently sinuate bole, but sometimes straight and cylindrical, up to 125 cm in diameter but usually much less, buttresses thick, rounded and concave but usually small or absent; outer bark thin, smooth and hoop-marked, often grey mottled, becoming patchily flaked in large trees, occasionally scroll-marked, inner bark pinkish-brown or pale brown, homogeneous, with darker phloem fibres; crown irregular and oblong, sympodial; young twigs and other young parts usually caducous powdery tomentose.
Leaves alternate, simple and entire, with curved secondary veins and reticulate tertiary venation; petiole not geniculate; stipules small, soon caducous.
Inflorescences racemose or sometimes partially cymose, irregularly branched and short, rarely spreading, few- to many-flowered.
Flowers bisexual, actinomorphic, 5-merous, ovoid to lanceolate in bud; sepals fused at base or more or less free, subequal, densely hairy; petals free, contorted, narrowly oblong, hairy, white to pale yellow; stamens (5-)15, in 3 whorls, short, filaments broad at base, tapering below anthers, anthers broadly oblong, with short but stout appendage to connective; pistil 1, ovary superior or semi-inferior, broadly ovoid or conical, densely pubescent, style short but stout and columnar, stigma prominent, often obscurely 3-lobed.
Fruit a broadly ovoid or globose nut, surrounded by a fruit calyx with equal or unequal lobes, adnate to the fruit or not and fused with each other (forming a cup) or not, sometimes fruit sepals corky, sometimes reflexed.
Seedling with epigeal or hypogeal germination; usually with non-photosynthetic magenta to pale yellow cotyledons remaining within the fruit; first pair of leaves usually opposite with interpetiolar stipules, subsequent leaves arranged spirally.

Wood anatomy

Macroscopic characters

Heartwood red-brown, sometimes with an olive tinge, darkening on exposure to dark red-brown, clearly demarcated from the pale yellow-brown sapwood.
Grain straight to shallowly interlocked.
Texture fine and even; occasionally silver figure present on quarter-sawn surfaces.
Growth rings usually indistinct; vessels small to moderately large, visible to the naked eye, moderately numerous to numerous, vessel lines conspicuous on longitudinal surfaces, particularly in species with large pores, tyloses variable in amount, usually abundant; parenchyma moderately abundant, rather indistinct with hand lens; rays of two sizes, fine and wider rays individually distinct to the naked eye; ripple marks absent.
Axial intercellular canals approximately half the size of largest vessels, scattered singly or in pairs, rarely in tangential series, empty or filled with chalky white deposits of dammar.

Microscopic characters

Growth rings indistinct.
Vessels diffuse, 11-50/mm², with varying proportions solitary, ranging from predominantly solitary (over 95%) to proportions less than 90% solitary, short multiples in V. coriacea, V. granulata, V. havilandii, V. javanica, V. oblongifolia, V. pauciflora, V. rassak and V. umbonata, uniformly distributed, mostly round to oval, sometimes slightly angular, average tangential diameter (60-)120-150 μm; perforation plates almost exclusively simple, multiple perforations of complex form occasionally present in V. granulata; intervessel pits rare in species with predominantly solitary pores, loosely alternate when present, tending opposite to scalariform in V. granulata, V. havilandii, V. mangachapoi, V. sarawakensis and V. umbonata, vestured, pit border diameter 5-7 μm; vessel-ray pits simple, rounded, large, c. 20 μm; tyloses variable in amount, few to abundant.
Fibres 1.5-1.7 mm long, non-septate, moderately thick- to very thick-walled (in species with denser wood), bordered pits distinct to indistinct, mainly in radial walls.
Parenchyma paratracheal, partially surrounding pores, to aliform with short wings, diffuse to diffuse-in-aggregates, occasionally forming short lines several cells wide, surrounding axial intercellular canals; fine terminal or initial bands present in V. borneensis, V. coriacea, V. havilandii, V. nitens and V. sarawakensis, in 2-6-celled strands.
Rays of 2 sizes, 6-8/mm, uniseriate and multiseriate 4-7(-10) cells wide, up to 1.5 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 invariably absent.
Large prismatic crystals present in ray cells of many species.
Horizontal intercellular canals absent; axial intercellular canals diffusely scattered, sometimes in pairs, (40-)60-150(-200) μm in diameter, commonly occluded.

Species studied: V. borneensis, V. coriacea, V. dulitensis, V. granulata, V. havilandii, V. javanica, V. maingayi, V. mangachapoi, V. micrantha, V. nitens, V. oblongifolia, V. pauciflora, V. odorata, V. rassak, V. sarawakensis, V. umbonata, V. venulosa, V. vinosa.

The diffuse axial gum canals distinguish resak ( Vatica and Cotylelobium ) from Dipterocarpus, Dryobalanops, Hopea and Shorea . Anisoptera can be distinguished from Vatica by its larger vessels and the lower density and distinctive yellowish colour of the wood. Vatica is readily separated from Cotylelobium by the absence of silica. The larger vessel frequency and more frequent radial multiples distinguish Vatica from Upuna.

Growth and development

The growth rate of resak trees is usually rather slow. However, a V. pauciflora tree planted in Peninsular Malaysia was reported to flower when only 5 years old. V. rassak may flower almost annually.

The fruits of some species (e.g. V. pauciflora, V. rassak, V. umbonata) seem to be adapted to dispersal by water: they are large, have short sepals and a thick corky pericarp. Other species with wing-like fruit sepals may be dispersed by wind, but undoubtedly the vast majority of the comparatively heavy fruits fall very close to the parent tree.

Other botanical information

The large variability of fruit calyx characters in Vatica s.l. as described here has led to the genus being subdivided into 3 sections. Some taxonomists prefer to value these sections as different genera: Vatica s.s. having 5 equal calyx lobes (about 22 species in Malesia), Sunaptea having 2 long and 3 short fruit calyx lobes (about 27 species in Malesia), and Pachynocarpus with thick, corky calyx fused to the fruit (2 species in Malesia). On sectional level, Pachynocarpus is often merged with section Vatica.

The group as a whole is characterized by the uniform flowers and also by characteristics of the wood anatomy. Vatica is closely related to the small genus Cotylelobium, which provides similar timber, but which differs in the leaf venation (secondary veins anastomosing to form a distinct intramarginal vein), its narrower and hairy anthers and longer style, and the presence of silica in the xylem. Cotylelobium is sometimes considered as belonging to the genus Sunaptea having a similar fruit calyx. Vatica trees are often difficult to identify unless fruiting.

Ecology

Resak is common but occurs scattered in lowland primary rain forest, the trees often becoming more numerous inland. It often occurs in forest on alluvial soils and near rivers, and on hills, particularly on ridges. Vatica species sometimes grow semi-gregariously, e.g. V. pauciflora, V. rassak and V. umbonata on river banks and floodplains, but occasionally also on dry ridge crests. Some species occur in hill forest up to 1600 m altitude; above 1000 m V. dulitensis, V. granulata, V. oblongifolia and V. odorata are found. The various species show a wide range of soil requirements. They may grow in heath forest (kerangas), on podzols (e.g. V. coriacea) or on yellow sandy soils (e.g. V. borneensis, V. oblongifolia). Resak trees are usually understorey trees, and only occasionally occupy the main canopy (e.g. V. rassak in the more seasonal areas of New Guinea).

Propagation and planting

Seeds lose their viability within a few weeks. Fresh seeds have a high germination rate, and germination starts after 3-6(-10) weeks. Natural regeneration is often abundant when openings in the canopy are present, but only few seedlings reach maturity. The seedlings need shade.

Seeds can be sown in the nursery. The best germination media for V. mangachapoi are sand, sawdust, or a mixture of both. Seedlings can be transplanted into the field when 30-50 cm tall. Planting should be done in the shade and with a spacing of 3 m × 2 m. Propagation by stump cuttings taken from seedlings about 1 m tall is possible. V. pauciflora was successfully propagated from cuttings of 4-year-old stems by treatment with 0.2% indole butyric acid, and by taking short cuttings of one leaf and one bud from half-ripe wood of juvenile plants. Stump transplants of V. odorata in Peninsular Malaysia and of V. pauciflora in Indonesia showed a high survival rate.

Inoculation with mycorrhiza improves shoot/root ratio and increases the growth rate of seedlings. In experiments with V. pauciflora, inoculation with Scleroderma sp. showed better results than with Russula sp. and Boletus sp.

Silviculture and management

Resak is too small and growth rates are too low to justify silvicultural investment. Natural regeneration can be stimulated by opening the canopy 3-5 years before logging operations start, following the selective cutting system. After logging, resak may regenerate vigorously. However, as most species grow slowly, particularly the heavy species, adequately long cutting cycles are necessary.

Diseases and pests

The fungus Fusarium sacchari has been reported to cause brown leaf-spots, defoliation and bark necrosis at the root collar and on roots of V. pauciflora.

Harvesting

In Indonesia, Vatica spp. are harvested selectively with a diameter limit of 50 cm at breast height. The main defect of the logs is hollowness, especially in large trees. Many logs of resak timber sink in water and must be transported over land or rafted together with floating logs. This hinders the exploitation of stands, although resak trees often occur near rivers.

Genetic resources

Most Vatica species occur scattered in primary forest, which makes them liable to genetic erosion in areas where large-scale logging operations are carried out. Some species are rare, e.g. V. bantamensis (Hassk.) Miq., of which apparently only a few trees are left in western Java at the Ujungkulon Nature Reserve.

Prospects

Little information is available on propagation, silviculture and growth of resak. Some species showed promising results in experiments with regeneration and enrichment planting after selective logging. However, many others are probably slow growers (those with heavy wood), and research should be directed towards the more fast-growing species (with comparatively lighter wood), such as V. rassak.

Literature

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.
Burgess, P.F., 1966. Timbers of Sabah. Sabah Forest Records No 6. Forest Department, Sabah, Sandakan. pp. 226-235.
Elouard, C., 1989. Notes on some Fusarium and Cylindrocarpon on Dipterocarpaceae in Indonesia. Biotropica 3: 25-40.
Garcia, P.R., Castillo-Borboran, L. & Dionglay, M.G., 1983. Germination of narig (Vatica mangachapoi Blanco) and red lauan (Shorea negrosensis Foxw.) seeds in various media. Sylvatrop 8: 133-137.
Hallé, F. & Kamil, H., 1981. Vegetative propagation of dipterocarps by stem cuttings and air-layering. Malaysian Forester 44: 314-318.
Lim, S.C., 1982. Malaysian timbers - resak. Malaysian Forest Service Trade Leaflet No 62. Malaysian Timber Industry Board, Kuala Lumpur. 9 pp.
Martawijaya, A., Kartasujana, I., Kadir, K. & Prawira, S.A., 1986. Indonesian wood atlas. Vol. 1. Forest Products Research and Development Centre, Bogor. pp. 128-133.
Momose, Y., 1978. Vegetative propagation of Malaysian trees. Malaysian Forester 41: 219-223.
Ng, F.S.P., 1980. Flowering of Vatica wallichii at 5 years. Malaysian Forester 43: 393-394.
Santoso, E., 1989. The effect of mycorrhiza on the stem diameter and dry weight of dipterocarp seedlings. Buletin Penelitian Hutan 504: 11-22.

Selection of species

Authors

R.H.M.J. Lemmens (general part, selection of species),
I. Soerianegara (general part),
W.G. Keating (properties),
W.C. Wong (properties),
J. Ilic (wood anatomy)