Pinus (PROSEA Exudates)
- Protologue: Sp. pl. 2: 1000 (1753).
- Family: Pinaceae
- Chromosome number: x= 12; 2n= 24 (for most species)
Major species and synonyms
Pinus kesiya Royle ex Gordon, Loudon, Gard. Mag. 16: 8 (1840), synonyms:
- P. insularis Endl. (1847),
- P. khasya Royle ex Hook.f. (1888).
Pinus merkusii Jungh. & de Vriese, Pl. Nov. Ind. Bat. Or.: 5, t. 2 (1845), synonyms:
- P. sumatrana Jungh. (1846),
- P. merkusiana Cooling & Gaussen (1970).
P. kesiya :
- Benguet pine, Khasya pine (En)
- Pin à trois feuilles (Fr)
- Philippines: saleng (general), tapulao (Zambales), bariat (Bontoc)
- Burma (Myanmar): tinyu
- Laos: khoua, mai hing
- Thailand: son-sambai (central), chuang, kai-plueak-daeng (northern)
- Vietnam: thông ba lá, xà nu.
P. merkusii :
- merkus pine, Mindoro pine, Sumatran pine (En)
- Indonesia: tusam (general), damar batu, damar bunga (Aceh, Sumatra)
- Philippines: tapulau (Sambali, Tagalog)
- Thailand: son-songbai, son-haang-maa (central), kai-plueak-dam (northern)
- Vietnam: thông nhựa, thông hai lá.
Origin and geographic distribution
Pinus comprises slightly more than 100 species. Its evolutionary origin has been located in the early Jurassic or late Triassic period. The earliest fossil records are all from eastern Siberia. The present-day centres of diversity are located in Mexico, the eastern United States, and the mainland of eastern Asia. Only 2 species occur naturally in the Malesian region: P. kesiya (eastern India, Burma (Myanmar), Indo-China, southern China, northern Thailand and the Philippines (northern Luzon)); and P. merkusii (eastern Burma (Myanmar), Indo-China, southern China, northern Thailand, the Philippines (Mindoro, western Luzon), Sumatra (Aceh, Tapanuli region, Kerinci mountain)). Thus P. merkusii is the only Pinus occurring south of the Equator. P. kesiya is planted throughout the tropics, in South-East Asia in Thailand, the Philippines, Malaysia and Papua New Guinea whereas P. merkusii is mainly planted in South-East Asia.
Pines are tapped worldwide for the resin the sapwood exudes when only the cambium or both cambium and sapwood are injured. "Gum rosin" and "gum turpentine" are produced from this so-called "crude resin" by steam distillation. Rosin and turpentine can also be obtained as a by-product of the sulphate or Kraft process in pulping pine wood ("tall oil rosin" and "sulphate turpentine") and by extracting from the stumps of pines long after they have been felled, which yields "wood rosin" and "wood turpentine". Rosin, a brittle, transparent, glossy, faintly aromatic solid, has a wide range of applications, such as in the manufacture of adhesives, paper-sizing agents, printing inks, solders and fluxes, various surface coatings, insulating materials for the electronic industry, synthetic rubber, chewing gums, soaps and detergents. Whereas the use of rosin for paper size is decreasing, it is increasing for the manufacture of printing inks. Turpentine, a clear liquid with a pungent odour and bitter taste, is used either as a solvent for paints and varnishes, or as a raw material for fractionation and value-added derivative manufacture of fragrances, flavours, vitamins, polyterpene resins and adhesives. Its use as a solvent has now largely been replaced by "white spirit" derived from petroleum. The biggest single turpentine derivative, synthetic "pine oil", is used in disinfectants, cleaning agents and other products with a "pine" odour. Other derivatives including isobornyl acetate, camphor, linalool, citral, citronellol, citronellal, and menthol are used either on their own or in the elaboration of other fragrance and flavour compounds. The resin of P. merkusii, known as "gondorukem" is one of the ingredients in the wax used for the manufacture of batik fabric.
Pine is a good general-purpose timber, although in woodworking and finishing aspects its resinous nature requires special attention. It is an excellent construction material. In the mining area of P. kesiya in northern Luzon, the Philippines, it is used as mine props. It is also used as piles, posts, Christmas trees, and as raw material for pulp and paper. Pine trees also make good fuel, both for cooking and heating. The wood of Pinus grown in Malesia is moderately hard to hard, but the heartwood is not very durable.
P. kesiya is also planted as a soil stabilizer to prevent erosion.
Production and international trade
"Naval stores" is the commercial name for a number of pine-derived products including gum rosin, wood rosin, tall oil, turpentine, tar, pitch, pine oil and terpene isolates. The name dates back several centuries, to when tar and pitch were used for caulking and weatherproofing the timbers and rigging of wooden ships. The 1994 world production of rosin was 1.2 million t annually of which 60% was gum rosin (valued at US$ 420 million), 35% tall oil rosin and 5% wood rosin. The annual world production of turpentine is 330 000 t of which an estimated 30% is gum turpentine (valued at US$ 50 million) and the remainder mainly sulphate turpentine. Early in the 1990s the annual turpentine production of China was 50 000 t (of which 5 500 t was exported), that of Indonesia 12 000 t (of which 7 500 t was exported). Indonesia produces about 10% of the total crude resin worldwide and in 1993, it produced 69 000 t of rosin of which 46 000 t was exported. In Vietnam the annual production of crude resin was 2500 t over 1986-1990. Crude resin is obtained by tapping, which is labour-intensive and has therefore declined in recent decades, especially in the United States, Portugal, Spain, France and Brazil, due to high labour costs. In 1995 the price of gum rosin from Indonesia was US$ 650-670/t. The average price of gum turpentine early in the 1990s was US$ 1-1.5/kg, that of sulphate turpentine US$ 0.15-0.30/kg. The use of turpentine for aroma chemicals is currently growing by 3-5% per year and for resins and adhesives by 2-3%. Its use for pine oil manufacture and as solvent has halved since 1970, but still accounts for half of the total annual consumption. Of the total annual turpentine consumption 35% is absorbed by the flavour and fragrance industry, which in 1998 commanded prices over US$ 6/kg, and some 15% is used in the manufacture of resins and adhesives, where it costs US$ 2/kg (1998).
The Gayu region (central Aceh, Indonesia) has been an important area of production from natural forest; since 1925 the area under exploitation (and hence production) has risen sharply. In 1941 production in this region reached 12 000 t. In Java, production from plantations only started in 1947.
Nowadays turpentine and rosin are facing intense competition from synthetic, petroleum-based resins and derivatives.
Crude resin obtained by tapping living pine trees is a thick, sticky, but usually still fluid material. It is opaque (due to the presence of occluded moisture) and milk-grey. Typically, crude resin comprises 70-75% rosin, 15-20% turpentine and 10% foreign matter (pine needles, insects, etc.) and rainwater. Rosin is the brittle solid remaining as the involatile residue after crude resin has been steam distilled to obtain turpentine. It is insoluble in water but soluble in many organic solvents and consists primarily of a mixture of acids of abietic and pimaric type, with smaller amounts of neutral compounds. Since rosin is an acidic material and the manufacturer of downstream derivatives depends on its acid functionality, a high acid number (and saponification number) is also an indication of good quality. The better quality rosins usually have an acid number in the range 160-170. Rosin derived from P. merkusii has a higher acid number (190 or more) due to the presence of merkusic acid, a rather rare resin acid with two carboxylic acid groups. Rosin from P. merkusii in Indonesia is pale brown, has a softening point of 75-78°C, an acid number of 160-200 and a saponification number of 170-210. Anything above about 10% unsaponifiable matter would be considered a poorer quality rosin. The resin acid composition of rosin from P. merkusii is as follows: 10% sandaracopimaric acid, 15% isopimaric acid, 38% palustric acid, 16% abietic acid, 3% neoabietic acid, 8% dehydroabietic acid and 10% merkusic acid. Rosin from P. kesiya is dark red-brown; its acid number is 166-168.
Turpentine is a clear, flammable liquid, with a pungent odour and bitter taste. It is immiscible with water and has a boiling point over 150°C and consists of a mixture of organic compounds, mainly terpenes, and its composition can vary considerably (more so than rosin), depending on the species of pine it came from.
Theα-pinene andβ-pinene constituents of turpentine, in particular, are the starting material for synthesis of a wide range of fragrances, flavours, vitamins and polyterpene resin; β-pinene is favoured over α-pinene. Δ3-carene is a constituent of turpentine which is not preferred as it is difficult to manipulate. Turpentine from P. merkusii provenances from Tapanuli (North Sumatra) consists of almost pureα-pinene, various Aceh provenances contain more Δ3-carene, whereas samples from some provenances from Indo-China have a more complex composition with large amounts of α-pinene and Δ3-carene and significant amounts of limonene, β-pinene, myrcene and longifolene. Turpentine obtained from P. kesiya from Aceh (Sumatra) contains 90%α-pinene. The average α-pinene content, Δ3-carene content and the turpentine yield for 11 Thai provenances of P. merkusii were found to be 43-90%, 1-36% and 28-37% respectively. For 5 Philippine provenances the α-pinene and Δ3-carene content were 95-96% and 0-1.3% respectively. Provenances from Assam (India) of P. kesiya have a high β-pinene content (26-43% of the turpentine) whereas other provenances usually only contain 1-2% β-pinene and more. In Orissa, the composition of turpentine from P. kesiya is 44% α-pinene and 45% β-pinene.
"Sulphate naval stores" are the by-products recovered during the conversion of pine wood chips to pulp by the sulphate (kraft) pulping process. "Sulphate turpentine" is retrieved by condensation of the alkaline liquors. "Crude tall oil" is fractionated into various products including "tall oil rosin" and "tall oil fatty acids".
"Wood naval stores" are obtained from resin-saturated pine stumps long after the tree has been felled. When the sapwood has decayed, the stumps are uprooted, chipped and extracted with solvent to give "wood turpentine", "wood rosin", dipentene and "natural pine oil". Crude tall oil contains 30-50% resin acids and 25-40% fatty acids.
- Usually medium-sized, monoecious evergreen trees of 15-45(-70) m tall, usually with a straight bole and a diameter of up to 100(-140) cm; bole without buttresses but distinctly broadened at base in solitary trees; bark usually thick; branches in regular whorls, branchlets glabrous, with a leafless base.
- Leaves in mature trees of two kinds: scale leaves which are triangular-lanceolate, early deciduous, bearing the short shoots in their axils, and needle-like leaves, in clusters of 2-4(-5), the latter persistent for two or more years, either semicircular or triangular in cross-section and the margin often minutely toothed.
- Male strobili cylindrical, produced in clusters around the base of the young shoot, yellow or reddish, consisting of numerous scales, arranged spirally, each with 2 inverted pollen sacs.
- Female cones usually terminal or subterminal, very variable in outline, consisting of scales arranged spirally which are thickened at the apex (called the apophysis), and bearing a stout prickle, mucro or hook (the umbo); each scale bearing 2 ovules.
- Seed often egg-shaped with a coat of varying hardness, usually having a large papery wing.
- Seedling with hypogeal germination; cotyledons plumose; the primary leaves (scale leaves) appearing within a few weeks and secondary leaves (needle-like leaves) usually appearing during the second year; root system consisting of a taproot with fine roots near the soil surface and near the root tip.
P. kesiya :
- A large tree up to 45 m tall and up to 100 cm in diameter, bark thick, reticulately and deeply fissured, branchlets often pruinose with a waxy bloom.
- Needles in bundles of (2-)3(-4), very slender and flexible, (10-)12-21(-25) cm long, bright grass green.
- Mature cones up to 3 together, pendulous, ovoid to ovoid-conical, (4-)5-8(-10) cm long, subsessile or on a short stalk up to 10 mm long; apophysis beaked or flattened with a short, blunt, deciduous umbo.
- Seed small with a short wing 1.5-2.5 cm long.
P. merkusii :
- A large tree up to 50(-70) m tall and up to 55(-140) cm in diameter, bark thick forming plates and grey-brown underneath, but scaly and more reddish tinged upwards, branches heavy, horizontal or ascending.
- Needles in pairs, slender but rigid, 16-25 cm long, with persistent basal sheaths.
- Cones solitary or in pairs, almost sessile, cylindrical, 5-11 cm long, after opening twice as thick and ovoid, generally falling off soon; apophysis broadly tetragonal with a smooth, almost depressed umbo.
- Seed small with a deciduous wing of about 2.5 cm long.
Growth and development
Young trees of mainland provenances of P. merkusii take 3-5 years to pass through a so-called "grass stage" which is characterized by densely clustered and slightly longer needles and short shoots and minimal height growth. Their cones are less cylindrical, and the seeds nearly twice as heavy. However, Sumatran provenances of the same species have no "grass stage" and they develop rapidly in height. This improves their chances in the competition with weeds which grow vigorously in the moist climate. Mycorrhiza are required for successful growth and allow seedlings to survive in more adverse sites. Generally, pines grow according to Rauh's architectural model. The trunk is monopodial and grows rhythmically, and develops tiers of branches; the formation of cones does not affect shoot formation. P. merkusii sometimes develops "foxtails", plants without branches and without growth rings in the wood. In early stages of growth, trees of P. kesiya are prone to fire damage. The annual increment of P. kesiya in the Philippines is 1-2 cm in diameter and 0.5-1.4 m in height.
In plantations, trees of P. merkusii reach sexual maturity when about 20 years old. They bear cones every year, although seed production varies.
Pollination and seed dispersal is by wind. Sometimes birds, rodents and people who gather the seeds for food, also disperse them.
Other botanical information
On a world scale, 10 pine species are tapped commercially. P. massoniana Lamb. is the most important one yielding the majority of crude resin produced in China. The union of P. khasya and P. insularis into P. kesiya has been argued, because of their different field characteristics and products, and some authors contend that P. kesiya has not been properly described. In Sumatra three different strains of P. merkusii have been recognized (the Aceh, Tapanuli and Kerinci strains) which differ markedly in e.g. stem form, branching, bark, resin content and susceptibility to attack by the caterpillars of the moth Milionia basalis.
The naturally occurring pines of South-East Asia (P. kesiya and P. merkusii) inhabit a wide range of forest and savanna habitats. They are pioneers and their natural range is extended by colonization following disturbances such as fire. They grow, for instance, scattered in fire-prone grassland and woodland. The trees increase in number in recently disturbed areas. They are strongly light-demanding and habitually grow in pure stands. Pines grow naturally in South-East Asia only in strongly seasonal environments.
P. kesiya grows in areas with a mean annual rainfall of 700-1800 mm and a pronounced dry season. Mean annual temperature in the area of distribution is 17-22°C, mean maximum temperature of the hottest month 26-30°C, mean minimum temperature of the coldest month 10-18°C. It generally grows naturally above 1000 m altitude. It is locally common in northern Luzon, often occurring in open pure stands on steep slopes at elevations of 300-2700 m. The best stands are found in moist well-drained localities at high altitudes where the soil is rich enough for hardwoods but because of the elevation the commercial hardwood species cannot thrive.
P. merkusii occurs in areas with a mean annual rainfall of 1000-2800(-3500) mm, mean annual temperature 21-28°C, mean maximum temperature of the hottest month of 24-32°C, and mean minimum temperature of the coldest month 18-24°C. It mostly occurs below 1000 m altitude, in Mindoro it grows naturally as low as 60 m above sea-level. It is locally common in northern Sumatra up to 2000 m altitude.
Propagation and planting
Successful natural regeneration of pines is only possible where a relatively large amount of sunlight reaches the ground. In Sumatra ripe seeds are produced most abundantly between July and November, but viable seeds are produced throughout the year. Only cones that have just changed their colour from green to brown should be collected and air dried; in the Philippines P. kesiya cones can be harvested in November-January. The viability of seeds harvested from P. kesiya trees is not affected by tapping. Therefore seeds can be collected from superior seed trees, provided such trees are not tapped on more than 2 faces and not longer than 3 years. Per kg there are 55 000-62 500 dry seeds of P. kesiya and 58 000 seeds of P. merkusii from Sumatran provenances and 42 000-55 000 seeds from continental provenances. P. merkusii seeds can be stored after sun-drying for 5 days when the moisture content has decreased to 5-8%. They can be stored in polythene bags for 2 years in a refrigerator (4-6°C) or for 6 months in an airconditioned room (16-17°C) without appreciable loss of viability. Seeds germinate in 8-12(-21) days, and need no pretreatment. However, they are often soaked in cold water overnight before sowing. For P. merkusii seeds, a germination rate of 40-60% may be expected. When seedlings are 5-10 cm tall they are transplanted from the nursery bed to polythene bags.
Vegetative propagation of pines has had only minimal success. Marcotting of P. kesiya has been found possible with Sphagnum moss, pine sawdust and pine topsoil as marcotting medium. Marcotting should be done in May-June when pine trees are in a dormant growth stage. Branches in the middle of the crown with a diameter of 2-3 cm are best for marcotting. During dry periods the marcots should be watered.
Seedlings need ectomycorrhiza for optimal growth. Natural infection may occur locally, but a reliable method of inducing seedlings to form mycorrhizal associations is to expose them to saplings of 30-80 cm tall which are already infected. The "mother trees" are planted in the nursery beds a year before sowing, at a spacing of 1 m × 1 m. Another method of obtaining mycorrhiza is to mix ordinary topsoil from pine forests with potting medium (in a ratio of 1 : 4-10), or to inoculate with vegetative mycelia, spores, mycorrhizal capsules or tablets. The latter methods will probably gain importance in the near future. The fungi used for inoculation of pines in South-East Asia include Pisolithus tinctorius, Scleroderma sp., Thelephora terrestris, Cenoccoccum graniforme and Rhizopogon sp. Root pruning is done when the seedling height is 10-15 cm to reduce shoot growth and to boost root development. After about 8 months the seedlings of P. merkusii in nursery beds are 20-25 cm tall and ready for planting out in the field. Seedlings of P. kesiya may already be suitable for transplanting after 4-6 months. Planting out in the field is carried out at the onset of the rainy season at spacings of 4 m × 4 m (for resin production) or 3 m × 1-2 m (for timber production).
Virtually all crude resin production in Indonesia is based on extensive areas of P. merkusii plantations in Java. In 1991 the production came from about 100 000 ha, but the total area planted to this species in Java is about 400 000 ha and pine plantations are increasing on Sumatra, Kalimantan and Sulawesi. In the Philippines, P. kesiya is planted at 3 m × 3 m as a shade tree for coffee plantations.
Plantation establishment is generally easy, as pines are pioneer species and can be planted in the open. Weeding is done 2-4 times during the first year after planting, the frequency decreasing with increasing size of the trees.
For plantations in Aceh a tapping and thinning schedule has been worked out in which the trees to be thinned are heavily tapped 2-4 years prior to being felled. Between 7 and 19 years 4 thinnings take place, in which 75 trees for the first 2 thinnings and 50 trees per ha in the second 2 thinnings are tapped and removed.
Diseases and pests
Generally, damping-off in pines caused by different fungi in the nursery can be controlled by proper nursery techniques, especially by avoiding over-watering. Stain disease, possibly caused by Trichoderma koningii, has been observed in 80% of the 21-38-year-old trees in a P. kesiya plantation in Bukidnon (the Philippines). In the Philippines, bark beetles (Ips calligraphus), pine shoot moths (Dioryctria rubella) and pine tip moths (Petrova cristata) cause problems in plantations of P. kesiya and P. merkusii. Pine shoot moths have infested almost all young pine plantations. Their larvae tunnel and feed inside the shoots, thus reducing the quality of the timber. Moreover, they also attack the young cones of P. kesiya , thus reducing seed production. Pine shoot moths can be effectively controlled by using the insecticides fenitrothion (0.1%) and fenvalerate (0.2%), or by Bacillus thuringiensis when applied before the larvae bore into the shoots, although their effectiveness to control is also reported to be not significant. The main pests in northern Sumatra are members of the Psychid and Geometrid families (e.g. Milionia basalis), shoot- and stem-boring Pyralids, and local squirrels.
Pine trees in plantations can be tapped 10-15 years after planting when they have attained a diameter of at least 17 cm. In the Philippines, it is recommended to tap only P. kesiya trees with a crown length of at least 35% of the total height, as tapping other trees would not be economical. In Thailand, P. merkusii is tapped, but P. kesiya is not, as its resin yield is too small to be economically viable. Some countries have regulations which limit tapping to those trees with a diameter greater than about 20-25 cm. Different methods of harvesting have been experimented with, such as a reversed U-shape or V-shape (herringbone) in the bark or by drilling holes into the wood. However, the best and easiest method to apply is the "koakan" or "quare" method in which a rectangular tapping panel of 10 cm high, 9-12 cm wide and 1-2 cm deep is made, removing only bark and no or very little sapwood. A container is fixed to the tree to collect the viscous exudate. The panel is enlarged every 3 days by removing a strip of 0.5 cm of bark on the upper side of the panel. Resin flow stops after 3 days, hence every 3 days "streaking" or "rechipping" is done. The term "streaking", however, is occasionally also used to indicate the application of stimulant on freshly made cuts. It has been suggested to make streaks at an angle, to encourage the resin to flow faster into the cup, thus reducing contamination, but it is doubtful whether this is being applied on a larger scale. A stimulant is usually applied only where the bark and the sapwood meet, i.e. the cambium layer. Stimulant should never be applied to the sapwood, as this causes the sapwood tissue to die. In Indonesia, a stimulant composed of sulphuric acid and nitric acid at a concentration of 7.5% or 15% proved to be effective. Stimulant is not applied every 3 days when the trees are streaked, but every 8-10 days, when resin is collected. "Ethrel" added to the stimulant has been found to enhance resin yield. Tapping without the application of stimulants is more labour-intensive, as it requires more frequent visits. Scrape, the solidified resin on the wood surface of the panel, should only be removed towards the end of the tapping season, as it protects the bole from decay. Its quality is lower than that of resin collected in the containers and is processed separately.
It is fairly common practice to tap trees 3-5 years before being felled, including those to be felled in thinning operations. Tapping of these trees is more intense, with more and wider panels, than tapping trees destined to produce for a prolonged time. Tapping may continue for 20 years. Although even when little sapwood is removed, tapping does not impede the vigour of the tree; when acids are used as stimulants it does retard growth. High temperatures are conducive to good resin flow, while prolonged periods of high rainfall are not, and the extent of seasonal changes in climate will largely determine the period during the year for profitable tapping. In the tropics and subtropics tapping may be done all year round, although seasonal heavy rains may interrupt it.
The most important and obvious factor affecting resin yield of pines is the diameter of the trees tapped. There is a linear relationship between tree basal area and resin yield. Moreover, the bigger the proportion of the live crown, the greater the resin yield. The average annual yield of P. merkusii is 1.4-2.7 kg/tree, for plantations in Java it is 3 kg/tree for P. merkusii and 1.5 kg/tree for P. kesiya. The annual yield of P. kesiya trees with an average diameter of 50 cm in the Philippines is 1.6 kg without the application of a stimulant, and up to 4.1 kg when 60% sulphuric acid is used as a stimulant. The annual resin yield of young P. merkusii plantations (7-19 years) in Aceh by tapping the trees to be thinned is 340-520 kg per ha, the increase corresponding with the age of the trees. The production of 520 kg of resin is obtained from 50 trees. The minimum acceptable yield is around 2 kg/tree, as lower yields make the operation economically unviable.
Per t wood processed by sulphate pulping 15-20 kg of crude tall oil, i.e. 5-10 kg of tall rosin and 3-5 l sulphate turpentine are obtained.
Handling after harvest
Rosin is graded and sold on the basis of colour, the palest shades of yellow-brown being better quality and commanding higher prices. Commercial grades most often traded are WW ("water-white") and WG ("window-glass"), X is a superior grade sometimes traded, whereas darker grades are N, M, K, I, H and lower. Most rosin is used in a chemically modified form rather than in the raw state. Like rosin, turpentine is also a very versatile material chemically, and nowadays it is used mostly after further processing. It usually undergoes distillation to isolate the desirable chemicals (mainlyα-pinene andβ-pinene) which are then transformed into value-added derivatives.
The standard seed source areas for P. merkusii are Sumatra and Thailand. Seedlings raised from Sumatran seeds often miss the "grass stage" and are thus better suited for plantations. The sources of genetically superior P. merkusii seed in Sumatra should be protected. Natural stands of P. kesiya in the Philippines should be earmarked for seed collection and gene conservation. The natural areas of distribution of both pines in Malesia are comparatively small, and therefore their protection should be guaranteed.
The genetic variation has been studied in natural populations of P. kesiya and P. merkusii in Thailand and Vietnam. In P. kesiya considerable variability was found between individuals within a population, but only weak variability between populations. Remarkably, the opposite was true for P. merkusii, with very low variability between individuals of a population but high variability between populations.
International provenance trials of P. kesiya and P. merkusii have been established throughout South-East Asia and also in northern Australia; they are coordinated by the Oxford Forestry Institute (Oxford, United Kingdom). P. merkusii seed orchards have been established in Indonesia.
In the Philippines, P. merkusii logging and tapping heve been banned since the early 1970s.
In Thailand, trials on provenance hybrids of P. merkusii showed that hybrids of Thailand and Papua New Guinea provenances had better survival and height-growth than local provenances. There are no known breeding programmes for pines aimed at higher resin production.
While Chinese production of gum naval stores is unlikely to increase further, Indonesia has an ample (and growing) number of pine trees available for tapping and the potential to increase production significantly in the years to come.
- Coppen, J.J.W. & Hone, G.A., 1995. Gum naval stores: turpentine and rosin from pine resin. Non-wood forest products 2. Natural Resources Institute, Chatham, United Kingdom & Food and Agriculture Organization of the United Nations, Rome, Italy. 62 pp.
- de Laubenfels, D.J., 1988. Coniferales. In: van Steenis, C.G.G.J. & de Wilde, W.J.J.O. (Editors): Flora Malesiana. Series 1, Vol. 10. Kluwer Academic Publishers, Dordrecht, Boston, London. pp. 447-452.
- Greenalgh, P., 1982. The production, marketing and utilisation of naval stores. Report G170. Tropical Products Institute, London, United Kingdom. 117 pp.
- Kasmudjo, 1992. Usaha stimulansi pada penyadapan getah Pinus [A stimulation trial on tapping of Pinus for resin]. Duta Rimba 149-150: 15-20.
- Lange, W., 1997. Natürliche Baumharze - potentielle Erzeugnisse einer forstlichen Nebennutzung. Koniferenharze. - 4. Mitteilung: Kiefernharze [Natural tree resins - potential minor forest products. Conifer resins. Fourth communication: pine resins]. Holz-Zentralblatt 123(25): 356, 358.
- Lopez, F.R. & Valbuena, R.R., 1970. Improved pine oleoresin production and its prospects in the Philippines. Philippine Lumberman 16(2): 18-20.
- Plocek, T., 1998. Turpentine: a global perspective. Perfumer & Flavorist 23(4): 1-2,4,6.
- Suhardi, Sosef, M.S.M., Laming, P.B. & Ilic, J., 1993. Pinus L. In: Soerianegara, I. & Lemmens, R.H.M.J. (Editors): Plant resources of South-East Asia No 5(1). Timber trees: major commercial timbers. Pudoc Scientific Publishers, Wageningen, the Netherlands. pp. 349-357.
- van der Kloot, W.G., 1951. De winning van de balsem uit Pinus merkusii en de verwerking tot hars en terpentijn [The exploitation of Pinus merkusii resin and the production of rosin and turpentine]. Tectona 41: 259-285.
- von der Heyde, B., 1979. Multiple-use forest management. Resin-tapping of Pinus kesiya in the Upper Agno district, Region 1 - Luzon. Food and Agriculture Organization, Rome, Italy. 61 pp.