Agathis (PROSEA Timbers)
- Protologue: Trans. Linn. Soc., London 8: 311, t. 15 (1807).
- Family: Araucariaceae
- Chromosome number: x= unknown; A. borneensis: 2n= 26
Kauri: lightweight softwood, e.g. Agathis borneensis Warb., A. dammara (Lambert) Rich., A. labillardieri Warb.
- kauri pine, Amboyna pitch tree (En)
- Agathis indien, 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).
Origin and geographic distribution
Agathis is the most tropical genus of the Coniferae. Opinions differ on the number of species. Some authorities recognize 21 species, 11 of which occur in the Malesian area. Others, applying a broader species concept, distinguish 13 species, with only 4 occurring in the Malesian area. The natural distribution of the genus is from Peninsular Malaysia, Sumatra, Borneo, Sulawesi, the Philippines, the Moluccas, New Guinea and New Britain towards western Australia, the Solomon Islands, New Caledonia, Vanuatu, Fiji and northern New Zealand. There are centres of diversity in western North Queensland and New Caledonia. If a narrow species concept is adopted, a third centre can be recognized in Borneo. 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 subsequently occurred. 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 the natural range, especially in Irian Jaya. Outside the natural range, it has been planted in Java, India, Mauritius, tropical Africa, South Africa and Central America.
The wood of kauri is used as a general-purpose softwood, and has many uses. It is excellent for joinery, boat building (especially masts), construction under cover, household utensils, panelling, turnery, mouldings, packaging and foundry pattern making. More specific purposes are drawing boards and rulers, matches, matchboxes, pencils, furniture, battery separators, piano parts and artificial limbs. As the timber is odourless it was formerly used for food containers such as tea chests and butter boxes. It makes a good peeled veneer with an attractive colour and figure for decorative plywood panelling. Wood-wool boards are manufactured from kauri wood. Kauri is very suitable for the manufacture of wrapping, writing and printing paper and rayon-grade pulp. The wood is also suitable for the manufacture of charcoal and activated carbon.
The inner bark of kauri exudes a translucent or clear white resin which is called "copal" or "Manila copal". This resin used to be an important component of varnish and was used in the manufacture of linoleum. There is still a steady demand in the export market for specialized uses such as in varnishes for labels of food tins and photographic colour prints, reflector paint, as a component of paint for lines on roads and for fluxes. Local demand is still high and applications of the resin for varnish, incense, torches, illumination, for making patent leather, sealing wax, as a liniment and as an unguent to prevent the attacks of leeches have been reported. Kauri is also used in reforestation projects.
Production and international trade
The export of round logs from Indonesia was 425 000 m3in 1970 and increased steadily to 760 000 m3 in 1973. In the early 1980s, Agathis wood accounted for 2.3% of the export of forest products from Indonesia. In 1987 the export of sawn Agathis timber was 67 000 m3 (with a value of US$ 20.1 million) and in 1988 83 000 m3 (with a value of US$ 22.2 million).
Malaysia, especially East Malaysia, is also an important exporter of kauri timber. In 1987 Sarawak exported 22 000 m3 in log form (and only 108 m3 as sawn timber), and Sabah in the same year 130 000 m3 in log form (with a value of US$ 17.3 million, and an average price of US$ 133/m3). In 1992 the export of sawn kauri timber from Sabah was 37 000 m3 and of logs only 9000 m3 with a total value of US$ 18 million. In Peninsular Malaysia the largest export volume was reached in 1967 with 8300 m3 (round logs), and export decreased steadily to 3250 m3 in 1973. In the 1980s the export of sawn kauri from Peninsular Malaysia increased from 800 m3 (worth US$ 230 000) in 1981, to 3300 m3 (worth US$ 740 000) in 1986, to 6000 m3 (worth US$ 2.5 million) in 1989 and amounted to 5500 m3 (worth US$ 3.0 million) in 1990 and 3500 m3 (worth US$ 1.9 million) in 1992.
In the Philippines the log production of kauri was recorded as 7000 m3 in 1988, but no export was reported. There is now a total ban on cutting Agathis trees in the Philippines. The export of kauri logs is banned in Papua New Guinea.
In 1926 the world production of copal was 18 000 t, 88% of which came from Indonesia, 7% from the Philippines and 5% from Sabah. In 1977 the Philippines exported a total of 778 t of Manila copal worth US$ 325 000. In 1987 the export of copal from Indonesia was still 2650 t (with a value of US$ 1.7 million), but it decreased to 1230 t (with a value of US$ 650 000) in 1989. The area planted with kauri in Java is estimated to be about 8500 ha. Elsewhere, kauri is planted on a small scale.
Kauri is a lightweight softwood. The heartwood is pale yellow to straw-coloured, often with a pinkish tinge and not clearly differentiated from the sapwood; it may weather to pale golden-brown or pale pinkish-brown. The density is 360-660 kg/m3 at 15% moisture content. The grain is generally straight, texture very fine and even; the planed surface is lustrous. The wood has no distinct odour and is not resinous.
At 15% moisture content the modulus of rupture is 49-65 N/mm2, modulus of elasticity 9400-12 000 N/mm2, compression parallel to grain 29-34 N/mm2, shear 6-7 N/mm2, cleavage 26-30 N/mm radial and 31-43 N/mm tangential, Janka side hardness 1450-2430 N and Janka end hardness 2200-3060 N.
The rates of shrinkage are small to moderate, from green to 15% moisture content about 1.2% radial and 2.5% tangential, and from green to oven dry about 3.8% radial and 6.2% tangential. The timber air dries satisfactorily without significant defects; slight end checks and splitting are recorded. The air drying of 12 mm thick boards takes about 2 months, of 25 mm thick boards 2.5 months, and of 40 mm thick boards 5 months. The kiln drying of 2.5 cm thick boards to 10% moisture content takes 5 days; the preferred drying temperature is 53-83°C with corresponding relative humidity of 76% to 30%. Care should be taken to prevent blue stain.
The wood is easy to saw and plane. Boring and sawing sometimes give slightly rough surfaces. In general, turning, sanding and mortising give good results. The wood takes varnish well and can be lacquered after filling with putty. The resistance to splitting when nailed is rated as good. Kauri wood can be peeled at a 90° peeling angle without pretreatment to produce veneer of good quality. Sometimes the presence of spiralled grain causes a rough surface. Fine veneer can easily be glued with urea-formaldehyde to plywood, and it is also suitable for face veneer. The wood can be pulped by the sulphate process at a temperature of 150°C, a consumption of chemicals of 16%, and a boiling time of 14 hours. The yield of kraft cellulose is 52%. The pulp is suitable for making kraft paper. The wood can also be pulped by the sulphite process.
Kauri wood is rated as non-durable. Graveyard tests in Malaysia and Indonesia show an average service life in contact with the ground of 6 months to 1.5 year. The wood is very susceptible to subterranean and dry-wood termites and wood-rotting and wood-staining fungi; it is, however, reported to be resistant to powder-post beetle attack. The treatability with preservatives is rated as very easy to moderately difficult. Tests in Malaysia, using the standard open tank treatment and creosote, showed an absorption of 350-630 kg/m3, but tests in Indonesia, using the vacuum-pressure method, showed considerably less absorption. In Malaysia, treated test sticks proved very durable in contact with the ground.
Wood of A. borneensis contains 52% cellulose, 25% lignin, 13% pentosan, 1.1% ash and 0.1% silica. The solubility is 2.0% in alcohol-benzene, 0.6% in cold water, 1.3% in hot water and 7.3% in a 1% NaOH solution. The energy value of the wood is about 19 950 kJ/kg.
Tests on A. borneensis indicate that wood from plantations has a tendency to have thinner fibre walls, smaller fibre diameter and fibre lumen diameter, shorter fibres, less resistance to wood-rotting fungi, but better treatability than wood from natural forest.
Kauri copal is a translucent or clear white resin, slowly hardening on exposure to a white or yellow to dark brown, hard, ultimately brittle mass. It is soluble in alcohol; the melting point is between 115-135°C. It is a complex mixture of monoterpenes, diterpenes and sesquiterpenes, and contains dammaric acid, dammaran and a resin.
- Medium-sized to very large monoecious but strongly dichogamous trees of up to 60(-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, globular or umbrella-shaped in older ones, large branches often irregularly upturned.
- Leaves entire, very shortly petioled, subopposite to opposite, 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. Foliage buds globular, tightly covered with several pairs of overlapping scales.
- 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.
- Seed cones terminal, massive, oval 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.
Sapwood not distinct from the heartwood, whitish, heartwood pale yellow-brown, straw-coloured or buff, sometimes with a pinkish tinge, ageing to a golden brown colour; wood somewhat lustrous, caramel-like odour present. Grain straight. Texture very fine and even. Growth rings barely distinguishable, but backsawn faces generally with some figure; rays very fine, not visible to the naked eye and generally not prominent on the radial surface.
Tracheids irregularly polygonal, rounded to square in cross-section, radial diameter approximately 50μm (up to 70μm in the earlywood), 3-6(-8) mm long, resin plugs abundant; intertracheid pits alternate in 1-2(-3) rows, large and hexagonal to flattened; pits on tangential walls rare and smaller. Rays 6-8/mm, uniseriate, 2-7 cells high, large and open, end walls oblique or rounded, side walls usually not parallel; ray-tracheid pits bordered, small, 2-7 (mostly 4-6) per crossfield.
Species studied: A. borneensis, A. dammara.
Anatomically it is very difficult to distinguish wood of Agathis spp. from wood of Araucaria cunninghamii Aiton ex D. Don. Generally, Agathis wood is slightly denser and free of compression wood; the heartwood is slightly darker. Agathis is devoid of the very small pin knots usually seen in Araucaria. Ray height in Agathis is often less than in Araucaria.
Growth and development
Seedlings need shade and show slow growth during the first years. Afterwards, when released from competition with herbs, growth is rapid, as in most typical primary rain forest trees. 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. Annual volume increment may be 20-30 m3/ha. 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. The root system is sensitive to lack of oxygen and the trees do not tolerate waterlogging.
Kauri is reputed to be a self-pruning tree, but open-grown trees of some species and provenances retain their low branches for some time. In general, the stem form is good.
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.
Other botanical information
The genus Agathis is one of the two genera in the family of Araucariaceae. All recent authors agree that the most useful characters to distinguish species are the shape and size of the microsporophyll and to some extent the male cone, which must both be studied in their mature stage. Agathis is subdivided into three sections, section Prismobracteata Meijer Drees with sharply angled microsporophylls, section Rostrata de Laubenf. with a distinct beak on the seed scale and section Agathis with no such beak. The differences between two recent revisions of Agathis (Whitmore, 1980 and de Laubenfels, 1988) are considerable and it is not possible to make a good synthesis of the two. Here, for the sake of uniformity the Flora Malesiana treatment (de Laubenfels) has been followed, except that the name Agathis dammara has been used again, because the proposed rejection of this name was not accepted by the Committee for Spermatophyte Nomenclature. Whitmore (1980) and de Laubenfels (1988) have distinctly different opinions on the number of species that can be recognized in Agathis. According to Whitmore, A. dammara and A. celebica represent one single species. He concluded that the best taxonomical solution would be to consider A. dammara, A. borneensis, A. australis (Lambert) Steud. and their New Caledonian relatives as infraspecific taxa of one species, but this has not been done because of the radical consequences for established nomenclature.
A. australis from New Zealand is probably the best known Agathis species and has a long history as a timber. A. macrophylla (Lindley) Masters from the Solomon Islands, Vanuatu and Fiji is planted locally in Peninsular Malaysia and Indonesia.
Agathis is the conifer genus par excellence of lowland tropical rain forest. Within the Malesian area kauri 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(-2400) m altitude. In Malesia, kauri is confined to regions 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. Kauri occurs on a diversity of soils and in a wide variety of habitats. It has been found in places as divergent as heath forest, on ultrabasics, limestone and in peat-swamp forest. Kauri 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. Natural stands on sand ridges in swamp forest in Kalimantan contain 1-2.6 m3/ha of standing timber; A. borneensis is there associated with ramin (Gonystylus bancanus (Miq.) Kurz). Kauri is generally least successful in species-rich forest and as a rule does not tolerate stagnant water.
Propagation and planting
Natural regeneration may occur under shade near mother trees, but seedlings are often rare. They seem able to establish in secondary vegetation. Naturally established seedlings in plantations can be used as planting stock. The shade tolerance of several species allows them to be managed under a selective felling system, always maintaining a good forest cover, which is important on erosion-prone soils on steep hills.
Artificial regeneration is mainly by sowing. Seed supply is limited by the very rapid decline in viability and the high costs of collecting seed from species whose cones disintegrate. In Indonesia and Papua New Guinea cones are collected when they have ripened and become blackish-green. It is not easy to collect female cones, as they are produced mainly in the upper parts of the crown at the ends of branches. It is not recommended to collect fallen seeds. The weight of 1000 dry seeds is about 200 g. Seeds must be sown as soon as possible, because the viability drops rapidly, from 90-100% initially to zero after some weeks. Germination starts 6 days after sowing, 80% of the seedlings emerging within 10 days. Storage time can be extended by quick drying without heating, and storage at temperatures below 0°C. Air-dried seeds have a germination rate of 40-50% after 14 days, but this drops to zero after about 9 weeks. After soaking for 24 hours, seeds are directly sown on seed-beds, and covered thinly with soil. Seedlings prefer shade and will survive open planting only if the roots are minimally damaged and soil is moist. Plants are more resistant to exposure when more than a year old.
Potting stock at least 15 cm high, but preferably larger as small stock shows high mortality, is used for planting. The best nursery seedlings for transplanting are those of 1-1.5 years old and 25-60 cm tall. If the taproot is bent sharply when transplanting, the plant dies. Mycorrhizal association is easily formed with ubiquitous soil fungi. When planted in open terrain, e.g. under taungya systems, with food crops between the rows of kauri for 1-2 years, a shade plant, e.g. Leucaena leucocephala (Lamk) 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 side-shoots.
Trees for tapping are planted at a wide spacing of about 10 m × 5 m. Close planting, in Java 3 m × 3 m, encourages the formation of long branchless boles. In Papua New Guinea a spacing of 6 m × 6 m is often practised to make unmerchantable thinnings redundant; the self-pruning ability of the trees makes wide spacing possible.
Vegetative propagation, to overcome lack of seed, has proved 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. Root suckers can be produced several times from potted seedlings and are considered to be the most successful material for vegetative propagation. A. robusta has been propagated successfully by in vitro culture in Australia, using stem segments with 3-5 leaf axils, excised from the upper portion of the main stem of 2-year-old seedlings. The success rate of rooting was, however, only 5-20% on a medium of half-strength Murashige and Skoog inorganic salts plus growth regulators.
Silviculture and management
Commercial plantations should be on gentle slopes on well-drained soils with good aeration. Extensive clearing, often accompanied by burning, is required to prepare the sites. Initially it is preferable to retain some overhead shade from shade trees, but in the sapling period, openings in the canopy are needed for further successful growth. In plantations of A. dammara in Java (with initial spacing of 3 m × 3 m), the first thinning is often at the age of 6 years, and then every 3 years until the age of 20 years, and every 5 years afterwards. In Papua New Guinea, an extremely heavy thinning and tending of the upper canopy, leaving only trees of commercial value, is implemented around the age of 10 years. Selective felling, with a diameter limit, often benefits the natural regeneration of kauri.
Young trees seem to be sensitive to competition from grass and also to overgrowing by vines, so young plantations must be weeded. The usual rotation for pulpwood production is 20 years in Java, but a longer rotation is needed for timber production.
Diseases and pests
The rust Aecidium may infest seedlings in nurseries and young trees in the field. The symptoms are reddish-brown raised lesions on the leaf surface. The disease may slow down growth. Fungi of Gloeosporium are reported to infest young seedlings in seed-beds. Pink disease caused by Corticium salmonicolor may damage twigs, branches and finally whole trees. Several fungal diseases are associated with waterlogging. Diseases reported for kauri in the Philippines are seedling dieback caused by Colletotrichum gloeosporoides, seedling leaf blight caused by Phoma sp., seedling dry rot caused by Fusarium solani, and butt and heart rot caused by Fomes and Ganoderma spp.
In Papua New Guinea a seed-eating moth (Agathiphaga) is widespread and may severely damage seeds. The termite Coptotermes eliseae sometimes attacks trees in Papua New Guinea. Parrots and cockatoos feed on the cones of Agathis trees in New Guinea, and wild pigs and squirrels may destroy young plantations.
In natural stands, trees with a diameter of more than 50 cm or 60 cm are usually harvested for timber. The logs float in water and can be transported by river. Kauri wood must be dried immediately, as it is susceptible to blue stain.
Overtapping and incorrect tapping techniques have caused many kauri trees to die and stands to be depleted in several areas, e.g. in the Philippines and Sabah. To prevent trees from dying the following recommendations have been made in the Philippines: only trees over 40 cm diameter should be tapped, and tapping should not be done less than 30 cm from the ground; the width of vertical tappings should be 1-2 cm, that of horizontal tappings 30 cm; the distance between the cuts should be twice the width of the cut (for vertical tapping 4 cm, for horizontal 60 cm); the cambium should not be cut; hardened resin should be collected 2 weeks after tapping; after collection, a fresh cut should be made immediately above the first one, and the first cut closed; not more than 37.5 kg resin should be collected per tree.
Bigger diameter trees give more resin, and spraying 40% sulphuric acid on the freshly cut streaks of tapped trees increases the resin flow by dissolving the hardened copal on the surface. Resin is more abundant during dry months. Copal production can be increased by making a V-shaped cut and covering it with black plastic sheet.
The annual wood production of kauri planted in Java in a pulpwood rotation of 30 years is reported as 23-32 m3/ha, and in a plantation for veneer production in a 50-year-rotation 22-28 m3/ha. The total yield of pulpwood after 20 years is about 300 m3/ha, and the total yield of timber after 40 years 570 m3/ha.
In Palawan (the Philippines) kauri trees give an average annual yield of copal of 3.6 kg, but in other places in the Philippines annual yields of 1.8 kg and 0.6 kg have been reported. However, the annual yield of large trees can be as high as 10-20 kg.
Genetic resources and breeding
Kauri trees are easy to recognize and are sought for their resin and for timber. Natural populations have been seriously depleted. The once huge stands of A. borneensis in South Kalimantan for instance, with a standing volume of 100-400 m3/ha, have been exploited heavily for timber, and populations of A. dammara have been depleted in the Moluccas. A. philippinensis is declining in the Philppines because of unscrupulous tapping for resin, illegal cutting and deforestation.
Some protected areas contain very important gene pools of Agathis species, 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. In Australia, New Zealand and on the Pacific Islands conservation measures have been introduced to protect several endangered Agathis species.
Ex situ conservation can play an important role for some species, e.g. for A. dammara which is planted on a fairly large scale in Java. In 1979 a worldwide provenance trial was coordinated by the Oxford Forestry Institute (Great Britain); seed from the entire range of distribution of Agathis was sent to 19 countries.
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 improved resistance to diseases and pests.
Much information is available on propagation and silviculture. It shows that certain species of Agathis have good prospects for large-scale planting for timber and copal production. Vegetative propagation is an important field of research because of problems with seed harvesting and storage, and because it will allow mass production of superior provenances. More breeding programmes should be set up.
- Bowen, M.R. & Whitmore, T.C., 1980. A second look at Agathis. Occasional Papers, Commonwealth Forestry Institute No 13. 19 pp.
- de Laubenfels, D.J., 1988. Coniferales, 2. Agathis. In: van Steenis, C.G.G.J. & de Wilde, W.J.J.O. (Editors): Flora Malesiana. Ser. I, Vol. 10. Kluwer Academic Publishers, Dordrecht, Boston, London. pp. 429-442.
- Howcroft, N.H.S., 1987. Phenology and silviculture of New Guinea kauri pine (Agathis sp.). Klinkii 3(3): 53-64.
- Laurent, D., 1986. Kalimantan ramin and agathis, where do you come from and how are you harvested? Revue Bois et Forêts des Tropiques 211: 75-88.
- Martawijaya, A., Kartasujana, I., Kadir, K. & Prawira, S.A., 1986. Indonesian wood atlas. Vol. 1. Forest Products Research and Development Centre, Bogor. pp. 10-14.
- Quiniones, S.S., 1980. The diminishing almacigas in Palawan: a report. Canopy International 6(4): 1, 13-14.
- Smits, W.T.M., 1983. Vegetative propagation of Shorea cf. obtusa and Agathis dammara by means of leaf-cuttings and stem-cuttings. Malaysian Forester 46: 175-185.
- Suriamihardja, S., 1979. Seed characteristics of Agathis loranthifolia. Malaysian Forester 42: 214-220.
- Whitmore, T.C., 1980. A monograph of Agathis. Plant Systematics and Evolution 135: 41-69.
- Wong, T.M., 1981. Malaysian timbers - damar minyak. Malaysian Forest Service Trade Leaflet No 43. Malaysian Timber Industry Board, Kuala Lumpur. 5 pp.
Selection of species
- Agathis borneensis
- Agathis dammara
- Agathis endertii
- Agathis labillardieri
- Agathis lenticula
- Agathis orbicula
- Agathis philippinensis
- Agathis robusta
- Agathis spathulata
- I. Soerianegara (general part),
- N.R. de Graaf (general part),
- J.M. Fundter (general part),
- J.W. Hildebrand (general part),
- A. Martawijaya (properties),
- J. Ilic (wood anatomy),
- C.C.H. Jongkind (selection of species)