Agathis (PROSEA Exudates)

Plant Resources of South-East Asia Introduction

List of species

Agathis Salisb.

Protologue: Trans. Linn. Soc., London 8: 311, t. 15 (1807).

Family: Araucariaceae

Chromosome number: x= unknown; A. borneensis: 2n= 26

• Agathis borneensis Warb., Monsunia 1: 184, t. 80 (1900), synonyms: A. beccarii Warb. (1900), A. alba Foxw. (1909), A. latifolia Meijer Drees (1940).

• Agathis dammara (Lambert) Rich., Comm. bot. Conif. Cycad.: 83, t. 19 (1826), synonyms: A. loranthifolia Salisb. (1807), A. celebica (Koord.) Warb. (1900), A. hamii Meijer Drees (1940).

• Agathis labillardieri Warb., Monsunia 1: 183 (1900).

• Agathis philippinensis Warb., Monsunia 1: 185, t. 8E (1900), synonyms: A. regia Warb. (1900), A. dammara auct. non (Lambert) Rich.

• General: kauri, kauri pine (En).
• Pin de kauri (Fr).
• Brunei: bindang, tulong
• Indonesia: damar (Java), damar sigi (Sumatra), damar bindang (Kalimantan)
• Malaysia: damar minyak (general), mengilan (Sabah), bindang (Sarawak)
• Papua New Guinea: kauri pine
• Philippines: almaciga (general), bidiangao (Negros), bagtik (Palawan)
• Thailand: son-khaomao (Bangkok).

A. borneensis :

• Brunei: bindang
• Indonesia: bembueng (south-eastern Kalimantan), damar pilau (Dayak, Kalimantan), hedje (Sumatra)
• Malaysia: damar minyak (general), bindang (Sarawak), tambunan (Sabah).

A. dammara :

• Indonesia: damar raja (general), kisi (Buru), salo (Ternate)
• Philippines: dayungon (Samar).

A. labillardieri :

• Indonesia: kayu damar putih (general), kessi, fuko (Irian Jaya)
• Papua New Guinea: New Guinea kauri.

A. philippinensis :

• Indonesia: goga, solo (Sulawesi)
• Philippines: almaciga (general).

Agathis is the most tropical genus of the Coniferae and the number of species varies with the species concept: the narrow concept recognizes 21 species, the wider concept only 13. Its natural distribution is from Peninsular Malaysia, Sumatra, Borneo, Sulawesi, the Moluccas, the Philippines, New Guinea and New Britain towards western Australia, the Solomon Islands, New Caledonia, Vanuatu, Fiji and northern New Zealand. It has been hypothesized that Agathis invaded the Malesian Archipelago and the Melanesian Islands from two Gondwanic centres, northern Queensland and New Caledonia, and that speciation has since occurred. If a narrow species concept is adopted, a third centre can be recognized in Borneo. The oldest fossil records date from the Upper Cretaceous of New Zealand and the Jurassic of Australia. Agathis is cultivated as a plantation tree and used in enrichment planting and reforestation in various areas within its natural range, especially in Irian Jaya. A. borneensis occurs in Peninsular Malaysia, Sumatra and Borneo. A. dammara occurs naturally in the Philippines (Palawan and Samar), Sulawesi and the Moluccas and is planted on a fairly large scale in Java. A. labillardieri occurs naturally and planted in western and central New Guinea. A. philippinensis occurs naturally in the Philippines, Sulawesi and the northern Moluccas.

Outside its natural range, Agathis has been planted in Java, India, Mauritius, tropical Africa, South Africa and Central America.

The inner bark of Agathis exudes a translucent or clear white resin which is called "copal" or "Manila copal"; "almaciga resin" is the copal from A. philippinensis. Manila was once the most important port of export, hence the name Manila copal. This resin used to be very important as a raw material for varnish as it has good storing quality, and the varnish film is very lustrous, elastic, and has good weathering properties. It has been used in oil and spirit varnishes, lacquers, paper size, paint driers, linoleum, oilcloth, waterproofing compounds, printing inks, adhesives, floor polish, shoe polish and for fluxes. Today, its major use is as a varnish for wood and paper. It is still used in road-marking reflector paints. Local applications of the resin are as varnish, incense, fuel for lamps and torches, sealing wax, as a liniment, as an unguent to deter leeches, smudges against mosquitoes, and in the manufacture of patent leather.

There are several identified uses of Agathis wood such as in the manufacture of veneer and plywood, sawn timber, furniture, panelling, musical instruments, pencil slats, carvings, toys, engineering instruments, household utensils, artificial limbs, and prostheses.

Indonesia is by far the biggest producer and exporter of Manila copal. In 1926 the world production of Manila copal was 18 000 t, 88% of which came from Indonesia, 7% from the Philippines and 5% from Sabah. In 1987 the export of Manila copal from Indonesia was still 2650 t (with a value of US$ 1.7 million), but over the period 1989-1993 exports fell to a remarkably constant level of about 1850 t. Exports in 1995 amounted to 1528 t. In 1982 Sarawak exported just over 50 t. Since then, Malaysia has exported only very small quantities. Production from natural stands and plantations of A. labillardieri in Irian Jaya amounts to several hundred tonnes of copal annually; the average annual export from Irian Jaya in 1954-1958 was 587-748 t. In 1977 the Philippines exported a total of 778 t of Manila copal worth US$ 325 000, in 1984 522 t worth US$ 237 000, in the period 1993-1997 the average annual export was 360 t worth US$ 261 000, and in 1998 355 t were exported with a value of US$ 254 000. The area planted with A. dammara in Java is estimated to be about 8500 ha.

Most Indonesian copal and some from the Philippines is shipped via Singapore. Germany (which also imports directly from Indonesia) is the major onward destination in Europe. India and Japan import modest quantities directly from Indonesia, whereas Taiwan is the largest importer of copal from the Philippines.

Copal from Leguminosae has also been exported from Africa (from Copaifera spp., Hymenaea verrucosa Gaertn. and South America (Hymenaea spp., notably H. courbaril L.).

Manila copal is a translucent or clear white resin, slowly hardening on exposure to a white or yellow to dark brown, hard, ultimately brittle mass. A. labillardieri, however, also yields a copal which remains soft ("papeda" or "Papua syrup").

Generally, three types of Manila copal are distinguished:

• "bua": a very hard, fossil or semi-fossil resin dug from the ground, probably originating from the roots, or collected from forks in the trees;

• "loba": a readily hardening copal obtained by tapping;

• "melengket": a copal remaining somewhat soft with a hard exterior, obtained by tapping.

Whether a tree yields "loba" or "melengket" copal depends on the species and not on the time between tapping and harvesting. The hardening of the resin is caused by evaporation of the essential oils in the resin and oxidation of other compounds. The oxidation process is accelerated when the copal is exposed to light. It is also a measure of the extent of polymerization. One authority states that the copal should be allowed to harden on the tree, as when it is not left on the tree the resin hardens less and yields another product. This phenomenon has not yet been explained.

The resin is a complex mixture of monoterpenes, sesquiterpenes and diterpenes and contains dammaric acid and dammaran. The following monoterpenes have been demonstrated: limonene in A. labillardieri copal and the unstable myrcene in A. borneensis copal. The monoterpenesα-pinene,β-pinene and limonene are found in almaciga resin. The diterpenes in Manila copal are agathal acid, agathol acid and agathis-dicarbon acid; they are present in amounts of 13.5% in hard copal and 6.8% in soft copal. Recent resin and young fossil resin contain 1-11% turpentine. The resin is soluble in ethanol and acetone, but partly soluble in petrol, benzene, terpuntine, and chloroform. The compounds found in the ethanol-soluble fraction are 9% sandaracopimaric acid, 8% acetoxyagathol acid and 38% agathal acid. "Melengket" dissolves easily in ethanol, whereas "loba" dissolves only partly. The solubility in alcohol does not depend on the period between exudation of the resin and harvesting but on the type of copal. Philippine samples from A. philippinensis were 67-97% soluble in 95% ethanol, regardless of their acid and saponification numbers. The melting point of the hardening copal of A. labillardieri is about 100°C and 70-80°C for its soft copal. For other Agathis species the melting point is between 115-135°C and increases with increasing hardness of the samples.

The acid number is an indication of the amount of free acids present per gram of the resin. Resins with high acid numbers are disadvantageous when used for paints and varnishes because of livering or stiffening when combined with basic pigments. They are more suitable for the preparation of paper sizes. The acid number is about 140 for the hardening resin from A. labillardieri and about 120 for its soft resin. A. philippinensis resin samples show a large variation in acid number: 81-170. The saponification number is 147-204 for A. philippinensis samples. Darker specimens of resin gave higher acid and saponification numbers than did lighter-coloured ones. When stored the acid number decreases but the saponification number increases, probably through oxidation. Manila copal is often chemically or thermally modified before it is applied in varnishes and paints. Thermal processing at 315-360°C for 2 hours makes the resin soluble in oils for application in oil varnishes. Esterification with glycerol neutralizes the natural acidity and renders the resin more soluble in drying oils for its use in paints and varnishes. The quality of the copal used for varnish is assessed differently due to different ways of varnish manufacture. Chemical modification of "almaciga resin" by formic acid yielded a product which compared favourably with the sizing performance of commercial rosin size.

Physical properties of the essential oil are: refractive index (20°C) 1.4714 and specific gravity (25°C) 0.8361.

The softer copals have the tendency to "block" when packed and during transport, i.e. the pieces of resin stick together and eventually become one hard block.

• Medium to very large monoecious but strongly dichogamous trees of up to 65 m tall; bole straight and cylindrical, up to 200(-400) cm in diameter, without buttresses but often with swollen superficial roots at base; bark surface at first quite smooth and light grey to reddish-brown, peeling with large, irregular roundish thick flakes leaving a pitted somewhat rough black or purplish-brown to fawn surface with an orange hue on larger trees; crown monopodial, usually eventually sympodial, that of young trees conical, but globular or umbrella-shaped in older ones, large branches often irregularly upturned.
• Foliage buds globular, covered with several pairs of tightly overlapping scales; leaves subopposite to opposite, very shortly petioled, entire, ovate to lanceolate, with a considerable variation in shape even along a single shoot, leathery, with many parallel veins that converge no more than slightly towards the apex, resin canals alternating with the veins.
• Male inflorescences consisting of pollen cones in or slightly above the leaf axils or seldom terminal, sessile or nearly so, more or less cylindrical, subtended by several pairs of scales forming a basal cupule, made up of numerous small spirally placed and narrowly stalked microsporophylls having a more or less peltate head bearing up to 12 pollen sacs.
• Female inflorescences consisting of terminal seed cones, massive, ovoid to spherical, woody; bracts spirally placed, their thickened apical margin blunt or in some species with a projecting flattened "beak", the lateral margins thin and broadly expanded but not membranous; seed scale complex fused with the bract, flat, with a single ovule.
• Seed attached along the base of the seed scale, more or less flattened and oval-shaped, the margin on one side greatly expanded from the basal part into an oval membranous wing, the other margin blunt or more often with a rudimentary and often acute wing.
• Seedling with epigeal germination; cotyledons two, opposite, broad and lanceolate with an acute apex, the first leaves are triangular scales, first normal leaves on lateral shoots.

• A. borneensis. A very large tree of up to 55 m tall; adult leaves ovate, 6-12 cm × 2-3.5 cm, with a more or less acute apex, resin canals paired; mature pollen cones cylindrical, 4-7 cm × 2-2.5 cm, subtended by a 2-10 mm long peduncle, microsporophylls with a spoon-shaped, slightly acute apical part of 5.5-6.5 mm × 4-5 mm, the apex a broad semicircle; mature seed cones ovoid, 6-8.5 cm × 5.5-6.5 cm, seed bracts roughly obtriangular with rounded upper edges and a strongly hooked projection on one side only; seed blunt on one upper corner and with a wing on the other corner.

• A. dammara. A very large tree of up to 65 m tall; adult leaves elliptical, 6-8 cm × 2-3 cm, tapering towards the rounded apex, with solitary resin canals; mature pollen cones ellipsoidal, 4-6 cm × 1.2-1.4 cm, subtended by a peduncle about 3 mm long, microsporophylls with a spoon-shaped apical part of about 2 mm × 2.5 mm, slightly angled at the apex; mature seed cones ovoid, 9-10.5 cm × 7.5-9.5 cm, seed bracts roughly obtriangular with a small projection near the base on one side; seed with a short acute projection on one upper corner and a wing on the other.

• A. labillardieri. A very large tree of up to 60 m tall; adult leaves ovate to ovate-lanceolate, 6-9 cm × 2-2.4 cm, acute, on a petiole 5-7 mm long; mature pollen cones ellipsoidal, 2.5-3.5 cm × 1-1.5 cm, subtended by a peduncle 2-6 mm long, apical part of the microsporophylls prismatic with a series of lateral sides and a flat hexagonal upper face 1-1.5 mm wide and long, the dorsal part sharply angled; seed cones not shattering on maturity, ovoid, 8.5-10 cm × 7.5-9 cm, seed bracts roughly obtriangular with nearly straight lateral margins and a distinct projection on one side and an indistinct one on the other; seed with a small and short, broadly acute projection on one upper corner and a wing on the other.

• A. philippinensis. A very large tree of up to 60 m tall; adult leaves ovate, 4.5-6 cm × 1.5-2 cm, tapering at base into a 5-8 mm long petiole, slightly to distinctly acute at the apex; mature pollen cones 2.5-4.5 cm × 1.0-1.1 cm, microsporophylls with a helmet-shaped and very slightly angled apex of 2-2.5 mm × 1.5-2 mm; seed cones ovoid, 7-9 cm × 12 cm, seed bracts obtriangular-ovate with broadly rounded upper corners and a small projection at the base on one side; seed with a broadly acute projection on one upper corner and a wing on the other.

Seedlings of Agathis need shade and show slow growth during the first years. Afterwards, when released from competition with herbs, growth is rapid. For A. labillardieri, height growth of trees amounts to 0.5-1.5 m annually, depending on soil characteristics and competition. Diameter increment can easily exceed 1 cm annually. Maximum age is unknown, but may be several hundred years.

Young trees have a cone-shaped taproot and thin horizontal lateral roots. In older trees most of the laterals grow vertically from the taproot and sometimes reach a depth of 12 m. Horizontal laterals grow just below the soil surface and may cover an extensive area.

In plantations in Java A. dammara starts to produce cones at the age of 15 years, but viable seeds are usually not produced before 25 years. Viable seeds can be collected from February to April and from August to October. In New Guinea ripe cones of A. labillardieri appear regularly in November and December, probably with more than 18 months between emergence and disintegration of female cones. Mature trees may produce 200-300 cones and approximately 1 kg of seed per year.

Many Agathis species produce seed cones well before pollen cones appear, promoting cross-fertilization. The seed cones usually shatter on the tree at maturity. Seeds are usually carried for only short distances by wind, and they often germinate in large numbers near the parent tree. Pollination is by wind.

Resin is produced and secreted by epithelial cells surrounding the resin ducts of the leaves. The resin formed in the epithelial cell is directly secreted into the resin ducts. A resin duct is a hollow tube that extends from the leaves to the bark of the stems and the roots.

The taxonomy of Agathis is still controversial. The naming adopted in the Flora Malesiana treatment has been followed here, but the name Agathis dammara has been reinstated because the proposal to reject this name was not accepted by the Committee for Spermatophyte Nomenclature.

Species can best be distinguished by the shape and size of the microsporophyll and to some extent by the male cone. Both of these must be studied in their mature stage. A. dammara is sometimes regarded as conspecific with A. philippinensis. A. labillardieri belongs to a group of species formerly known as Dammara alba Lam. or Agathis alba Foxw.

Agathis is the conifer genus par excellence of lowland tropical rain forest. Within the Malesian region Agathis occurs in lowland or lower montane tropical rain forest except for some populations in Peninsular Malaysia which thrive in upper montane rain forest. It occurs from sea-level up to 2000(-2500) m altitude. In Malesia, Agathis is confined to areas with an annual rainfall between 2000 and 4000 mm which is well distributed over the year. On Palawan (the Philippines) several small populations thrive in a climate with a more marked dry period. Agathis grows naturally in almost all of the Philippine mountain ranges on well-drained slopes or at altitudes of 200-2000 m above sea-level. It occurs on a diversity of soils and in many habitats. It has been found in places as divergent as heath forest, on ultrabasics, limestone and in peat-swamp forest. Agathis occurs as a solitary tree as well as a dominant and main or even sole canopy tree. In Malesia large stands are restricted to azonal soils. Agathis is generally least successful in species-rich forest and as a rule does not tolerate waterlogging. A. borneensis occurs scattered in upland rain forest up to 1200 m altitude in Peninsular Malaysia and Sumatra but in Borneo it is often found in pure stands on sandy peat soils at low elevation. A. dammara is scattered but locally common in lowland rain forest up to 1200 m altitude. A. labillardieri is locally common and seems to prefer slightly oligotrophic soils which are often podzolized, but it occurs on a wide variation of soil types from sea-level up to 1700(-2500) m altitude. A. philippinensis occurs scattered and often as an emergent tree in upland rain forest at (250-)1200-2200 m altitude. Generally, Agathis is best adapted to grow in rocky soil.

Agathis can be propagated by seed or by cuttings. Seeds of Agathis are difficult to store for a longer period as they lose their viability within a few weeks. Moreover, it is very difficult and thus expensive to collect seed from these large trees, as their cones disintegrate and it is not recommended to collect fallen seeds. A. borneensis has 4000 seeds/kg and A. dammara 4800-5200 seeds/kg. Seed of A. dammara stored in sealed containers for 6 months at 8°C showed 31% germination. After soaking for 24 hours, seeds are sown in seed-beds and lightly covered with soil. Seed of A. dammara germinates in 5-30 days. A. labillardieri seedlings are ready for planting out in the field when 1-1.5 years old and 25-60 cm tall. Mycorrhizal associations are easily formed with the ubiquitous soil fungus Endogone. Vegetative propagation, to overcome lack of seed, has proven successful, e.g. by root suckers from seedlings in the nursery, and by stem and leaf cuttings assisted by auxin applications. Stem cuttings should preferably be taken from young plants or low branches of young trees. Cuttings taken from plagiotropic branches can only be used for seed-orchard trees, as the resulting trees maintain their plagiotropic growth. Root suckers can be produced several times from potted seedlings and are considered to be the most successful material for vegetative propagation. A. borneensis cuttings 15-20 cm long with leaves left attached to the upper part were successful from coppice shoots but not from the branches of mature trees. Naturally established seedlings in plantations can also be used as planting stock. When A. labillardieri is planted in open terrain, e.g. under taungya systems, with food crops between them for 1-2 years, a shade plant, e.g. Leucaena leucocephala (Lam.) de Wit, should be sown in advance to provide the necessary shade. Planting during the dormant stage of terminal buds is preferable, and transpiration is reduced by clipping branches. Trees for tapping are planted at a wide spacing of about 10 m × 5 m.

Manila copal is collected in natural tracts of forest and, increasingly from planted trees. Agathis plantations, mainly A. dammara, are established for the production of timber or raw material for pulp and paper production. In Irian Jaya it has been reported that the local population has been planting Agathis trees in groups in the forest and collects wildlings to be planted in the villages.

The fungus Aecidium fragiforme causing rust disease in A. dammara has been observed in Ambon, Kalimantan and Java. In Java it is a serious disease on seedlings in areas with over 3000 mm annual rain. In A. philippinensis the following diseases have been observed: seedling dieback caused by Colletotrichum gloeosporoides, leaf blight by Phoma sp. and butt- and heart rot by Fomes pinicola. In Papua New Guinea a seed-eating moth (Agathiphaga) is widespread and may severely damage seeds. Stem rot caused by cutting tapping wounds into the sapwood may result in the tree dying because the stem breaks at the height of earlier tapping.

Most of the resin of Agathis produced nowadays is obtained by tapping rather than by collecting fossilized resin from the ground. Overtapping and incorrect tapping techniques have caused many Agathis trees to die and stands to be depleted in several areas, e.g. in the Philippines, Sabah and Sulawesi. In the Philippines recommendations for tapping without impairing the productivity or killing the tree (A. philippinensis) are as follows. Only trees at least 40 cm in diameter at breast height should be tapped. The bark is then scraped to remove loose material. The first tapping should be at a height no more than 30 cm from the ground. A horizontal cut 30 cm long and 2 cm wide is made; the distance between the cuts should be 60 cm or twice the length of the cut. When cutting, great care must be taken to avoid damaging the cambium, as the resin ducts are only found in the bark. Damage to the cambium and the sapwood first results in attacks by termites, after which wood-rotting fungi further attack the tree. Only if the cambium has not been damaged will the bark regrow and the wound heal. It is recommended to spray 50% sulphuric acid on the cut stem portion, to stimulate resin flow by dissolving the hardened copal on the surface. After 1-2 weeks the resin flow has hardened and a new cut 0.4-1 cm wide is made just above the first one. Be sure to always use a sharp-bladed knife to cut the bark to minimize damaging the cambium. In Indonesia harvesting is still done without the application of acid. Experiments using a 15% hydrochloric acid (HCl) solution increased the resin yield however, whereas higher concentrations changed the colour of the collected resin from transparent yellow to reddish-brown. In Java new incisions in the stems of A. dammara are made every 3-4 days. The resin of Agathis from South Sulawesi usually takes about 1 month to harden. Resin production is more abundant during dry months and can be increased by covering the wound with black polythene sheet. In Kalimantan a special tapping technique has been used for the production of high grade copal ("Pontianak copal"). The technique consists of severing the ends of branches from which the resin exudes. In the Philippines tappers need a licence defining the area and the amount of resin which may be collected.

Large Agathis trees have a higher resin production than smaller ones; however, trees over 1.3 m in diameter become less productive again. Thick-barked trees also yield considerably more than thin-barked ones. Yield also increases after the first few tappings up to one year; sometimes the resin from the first three tappings is not collected at all. The average annual yield of copal from A. philippinensis at several sites in the Philippines ranged from 0.6-5.6 kg/tree, with a maximum of 16 kg for very productive trees. In A. dammara treatment with 15% HCl solution increased the average yield per tree from 15 g to 25 g per collection every 6 days, i.e. from 0.9 kg to 1.5 kg annually. However, the annual yield of large trees can be as much as 10-20 kg. In Papua New Guinea a productive tree yields 20 kg of resin per year. In a survey in Palawan (the Philippines) in 1980, copal collecting raised about US$ 2.3 per man per day, which was considerably more than the agricultural wage rate at that time.

Grading Manila copal is important, because the different grades show fairly large differences in quality with regard to the intended use. The solubility in 95% ethanol is an important grade criterion. Other factors determinig the grade are the amount of impurities (e.g. pieces of bark, soil), and the colour and size of the resin particles. In the Philippines, 8 standard grades have been developed, based on these criteria. The grades formerly used in Indonesia represent three large groups with decreasing ethanol solubility: soft ("melengket"), semi-hard ("loba") and hard (including "bua"). Further grading takes into account the amount of impurities, and the colour and size of the resin particles. Recent Indonesian grades are "clean scraped chips", "medium scraped chips" and "small chips", with indicative prices per t in 1995 of respectively US$ 1500, 1000 and 900. Ethanol extraction and heating under pressure results in a hard and brittle, purified resin which can be formed into blocks. A similar treatment is given to "papeda" resin, yielding a "non-blocking" copal with a higher melting point and higher viscosity, but with a darker colour.

Natural Agathis populations have been seriously depleted. The once huge stands of A. borneensis in South Kalimantan for instance, with a volume of standing timber of 100-400 m³/ha, have been heavily exploited for timber. A. dammara populations have been depleted in the Moluccas and A. philippinensis is declining in the Philippines because of unscrupulous tapping for resin, illegal cutting and deforestation.

Some protected areas contain important gene pools of Agathis, e.g. Badas Forest Reserve in Brunei, Gunung Palung Nature Reserve in Kalimantan, Bukit Barisan Selatan National Park in Sumatra, and Taman Negara National Park in Peninsular Malaysia for A. borneensis. Mount Apo and St. Paul Subterranean River National Parks (the Philippines) have important stands of A. philippinensis. Ex situ conservation is important for A. dammara, which is planted on a fairly large scale in Java.

To improve the resin production of poorly productive stands of A. dammara V-grafting has been applied. It appeared that 2-year-old seedlings can best be used as grafting stock. Breeding of Agathis trees has been included in the national forest tree improvement programme in Indonesia which has 3 aims: improving wood quality and production, improving copal quality and production and improving resistance to diseases and pests.

Although synthetic resins have largely replaced natural ones, Manila copal still retains a sizable market share. In the Philippines recent research has shown its importance for the national economy. Quality control is essential, as mixed grades of Manila copal are hardly accepted by commerce. Although timber from Agathis is a much more important commodity, more attention should be given to resin production in timber plantations.

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A.B. Ella