Resin

RESIN

Most conifers will exude resin if wounded. Others will exude resin spontaneously from branches and cones. Several genera of conifers produce resin in copious quantities, which are then harvested and put to a wide variety of uses. These have made resin one of the most important non-wood products from conifers. The following sections describe some of the more important sources and uses of conifer resins.
RESIN FROM PINES
The resin harvested from various species of Pinus is undoubtedly the oldest and most important of the non-wood products from conifers. This subject has been discussed in-depth in a previous paper in this series (Non-Wood Forest Products Series nr. 2: Gum Naval Stores: turpentine and rosin from pine resin, Coppen and Hone 1995). Therefore, only a brief review will be given in this paper on pine resins, complemented by a review of resins obtained from other conifers. Resins obtained from non-coniferous trees are described in Non-Wood Forest Products Series nr. 6: Gums, resins and latexes of plant origin, Coppen 1995b.
Pines that are important commercial sources of resin
Species
Countries where important
P. brutia P. caribaea P. elliottii P. halepensis P. kesiya P. massoniana P. merkusii P. oocarpa P. pinaster P. radiata P. roxburghii P. sylvestris
Turkey Kenya*, South Africa*, Venezuela* Argentina*, Brazil*, Kenya*, S.Africa* Greece China China China, Indonesia, Vietnam Honduras, Mexico Portugal Kenya* India, Pakistan Lithuania, Poland, Russia

Sources
Resin products from pines are commonly called naval stores. This term dates back to the days when the British Royal Navy used large quantities of resin products from pines to waterproof ships (Mirov and Hasbrough 1976). Today, three classes of naval stores are recognized based on their source (Coppen and Hone 1995):
1. Gum Naval Stores - These are obtained by tapping the trunks of living pine trees. This is the traditional source of resin and is a labour intensive process.
2. Sulphate Naval Stores - Are obtained during the conversion of pine wood chips to pulp via the sulphate or Kraft pulping process. Sulphate turpentine is condensed from the cooking vapours. A product known as tall oil is obtained from alkaline liquors and fractionated into products such as tall oil rosin and tall oil fatty acids.
3. Wood Naval Stores - Are obtained from resin saturated pine stumps long after a tree has been felled.


Primary products
Distillation of pine resin yields two products: turpentine and rosin.
Turpentine It is a clear liquid with a pungent odour and bitter taste and is composed of a number of organic compounds, primarily a series of volatile fractions known as terpenes. The chemical composition of turpentine can vary significantly depending on the species of Pinus from which it is harvested. In some pines, the terpene composition is relatively simple and consists mainly of two common terpenes: alpha and beta pinenes. Other pine species contain different terpenes, which may significantly affect the composition and use of the turpentine. The resin of the North American pine, P. contorta, contains phellandrene, a terpene contained in plants of the parsley family and has a grassy fragrance. The resin of the Mediterranean species, P. pinea, and some North American species contain limonene. P. ponderosa resin contains a sweet smelling terpene, known as 3-carene. Two pines endemic to Pacific coastal regions of North America: P. sabiniana and P. jeffreyi, have no terpene components in their resin. Instead, they contain aldehydes which are much diluted with a gasoline-like material heptane which has no fragrance but is explosive (See textbox - "The gasoline tree"). Aldehydes mixed with heptane provide the characteristic vanilla-like odour associated with P. jeffreyi forests (Mirov and Hasbrough 1976).

THE GASOLINE TREE
At the beginning of the American Civil War, when Union forces were cut off from their normal turpentine sources in south-eastern United States, turpentine production was started in the pine forests of the California foothills. All went well if the resin was taken from ponderosa pine, Pinus ponderosa, but what turpentiners did not know was that the resin of Jeffery pine, P. jeffreyi, contained heptane, the same inflammable product found in petroleum. Even a trained forester or botanist can have difficulty separating these two species. Firing up primitive turpentine still loaded with pitch from Jeffrey pine was like building a fire under a gasoline truck. Heptane had to be distilled very carefully.
In 1890, a California druggist named D.F. Fryer, distilled heptane from Jeffrey pine in his laboratory and sold it as "Abietine" (oil of fir). In the 1900s, chemists determined that Jeffrey pine turpentine is 95 percent n-heptane (C7H16 ).
In 1924, the gasoline industry began tests that would ultimately result in smoother gasolines. A supply of heptane was needed for the research. Heptane from Jeffery pine was used in these tests for about two years, then a less complicated method of testing motor fuels was discovered. However, it was with the help of a pine tree that Dr Graham Edgar, then Research Director of the Ethyl Corporation, devised his now famous "octane" scale for measuring knocking qualities of gasoline (Mirov and Hasbrouck 1976).
Rosin It is the major product obtained from pine resin. It is the involatile residue that remains after the distillation of turpentine. Rosin is a brittle, transparent, glassy solid insoluble in water but soluble in a number of organic solvents (Coppen and Hone 1995).
Historical aspects
Pine resin has been an important commodity at least since biblical times, as attested to by the story of Noah receiving instructions from God to "pitch the ark within and without with pitch". The Roman statesman and poet Ausonius wrote about the tapping of pines for resin in Aquitania in the south-eastern part of France. The pine he referred to is Pinus pinaster.
The importance of pine resin to the British shipbuilding industry has already been mentioned. During the fifteenth and sixteenth centuries, when America was a series of British Colonies, the capacity of two indigenous pines: Pinus elliottii and P. palustris, to produce resins of excellent quality and quantity was recognized and naval stores became an important export commodity from the South Carolina and Georgia colonies. The tapping of resin from these pines was, until recently, a major industry in south-eastern United States when high labour costs reduced its profitability. Today, resin is produced in this region either via the sulphate pulping process or by extraction of resin from saturated pine stumps.
Pine resin was used in California long before the territory became part of the United States. The origin of the name "California" may be linked to pine trees and the resin they produced. Padre Arroyo, one of the early priests who converted the indians of California to Christianity and ultimately wrote a vocabulary of the California Indian languages, told an officer of Captain Beechey’s expedition in 1826 that the word "California" was a corruption of the Spanish word colofón meaning "resin" and that it was suggested by the numerous pines, Pinus radiata, that produced resin around the old Spanish capital of Monterrey (Mirov and Hasbrouck 1976).
In India, commercial tapping of resin from pines began in 1896 following a series of preliminary experiments from 1890 to 1895. The development of resin tapping in India has been entirely the work of the State Forest Departments but the idea for tapping the indigenous pine forests of the Himalayas originally arose after observing the extraction of crude resin by local people (Chaudhari 1995). In Bhutan, tapping of pines is often combined with the extraction of the essential oil "citronella" from lemon grass (Cymbopogon flexuosus), common in Chir pine forests (Pinus roxburgii) (Chamling 1996).

Species
Virtually all pines will yield resin if tapped. Key factors that determine feasibility for tapping are the quality (terpene content) and quantity of resin obtained. Today, only the diploxylon (hard) pines are commercially tapped. Both plantations and natural stands are tapped for resin and in some tropical or Southern Hemisphere countries where pines are not native, extensive pine plantations have proven to be excellent resin sources. Species, which are important resin sources today, are summarized in Table 6.1.
Effects of resin tapping on pines
If done properly, using methods which involve removal of bark only, tapping trees causes no damage to pines and they may be tapped for up to 20 years or more. Even the more traditional methods of tapping which involve some removal of woody tissue may not affect tree survival and trees can be seen in the wild with old tapping scars that seem otherwise quite vigorous. The risk of damage is heightened if excessive wood tissue is removed (Coppen 1995a).
In south-eastern United States, two insects are attracted to turpentine scars. The black turpentine beetle, Dendroctonus terebrans (Coleoptera: Scolytidae) is attracted by terpenes released by stumps and injured trees. Trees weakened by fire, logging or adverse climatic conditions or which have exposed resin due to naval stores operations are highly prone to attack. The turpentine borer, Buprestis apricans (Coleoptera: Buprestidae) deposits eggs on exposed wood, especially at the edges of turpentine faces or fire scars. The larvae tunnel in the sapwood and heartwood. This insect was very destructive when turpentine orchards were common in the United States. Borer riddled trees were so weakened that they became subject to wind breakage. The lumber value of these trees was virtually destroyed and gum production was reduced. Acid treatment to increase gum flow in naval stores operations eliminated dry faces that were attractive to these insects; thus preventing attacks (Drooz 1985). * Introduced species. Sources: Coppen (1995a), Coppen and Hone (1995), Author’s observations.
Uses
Unprocessed resin Whole, unprocessed resin has a number of traditional uses.
In Asia there are numerous records of the use of pine resin for medicinal purposes.
In the Karnali Zone of Nepal, the resin of Pinus roxburghii, known locally as Ahule sallo, is used to relieve the symptoms of a cough. About two grams of resin and an equal amount of common salt are boiled in 250 -300 ml of water and drunk warm before bedtime for 2-4 days.
The resin from Pinus wallichiana is used as a plaster for bone fractures. The resin is also mixed with an equal amount of butter and is warmed to make a paste. This ointment is applied to the affected parts regularly before bedtime to soften scar tissue (Bhattarai 1992).
In Uttar Pradesh State, India, the resin of P. roxburghii was applied to boils, heel cracks and on either side of the eye to reduce swelling (Singh et al. 1990).
A report from northern Thailand describes a traditional remedy for urinary problems. This consists of pitch from Pinus merkusii, mixed with the fruit of screw pine, Pandanus lucratus, and three river rocks collected from underneath a bridge. The mixture was boiled and drank (Anderson 1986).
In south-western United States, the Pueblo and Navajo Indians used the resin of various species of piñon pines to give their stone griddles a non-sticking surface, something like the Teflon of today. The Hopi Indians, of American south-west, used resin to repair broken ceramic pottery (Lanner 1981).
The Paya Indians of Honduras use the resin of Pinus oocarpa to kill "worms", presumably the larvae of bot flies which burrow into the skin of humans and domestic animals (Lenz 1993).
In Greece, the addition of pine resin to white wine (retsina) is a national tradition (see textbox).
Rosin and Turpentine For many years, both rosin and turpentine were used in an unprocessed form in the manufacture of soaps, papers, paints and varnishes. Today, they are the raw material used in the production of a wide range of products (Table 6.2).
Most rosin is presently modified and used in paper sizing, adhesives, printing inks, rubber compounds and surface coatings (Coppen and Hone 1995). Rosin is also applied to the bows of string instruments and to belting to reduce slipping. It is also used in brewing and mineral beneficiation (Chaudhari 1995).
A number of chemical products are derived from turpentine and rosin (Forbes and Meyer 1956).

RESIN ADDED TO WHITE WINE: A GREEK TRADITION
To a non-Greek, the first sip of retsina usually has a mysterious, sometimes unpleasant, taste. One must acquire a taste for this traditional Greek wine. Retsina is made as all wines except that it is lightly resinated, 2 parts/1 000 of pine resin is added to the must at the start of fermentation.
Retsina is a traditional appellation by law. No other country in the world is allowed to produce it.
Adding resin to wine is a process that dates back to antiquity when either pitch, pine resin or a combination of plaster and resin was used to make impermeable clay vases (amphorae) in which wine was transported. Ancient Greeks observed that pine resin not only helped seal the amphorae from moisture, but also helped to preserve the wine within. Pine resin may have also been used to squelch the scent of goatskin, in which wine was locally transported.
Cone wine is mentioned frequently in ancient Greek literature and Dionsysus is sometimes depicted with a pinecone at the end of his staff.
The resin is collected from aleppo pine, Pinus halepensis. The best resin comes from the Attica Region, near Athens. Approximately 85 percent of retsina is made from two varieties of grapes: Savtiano and Rhoditis. Retsina accounts for about 40 percent of total wine production in Greece. Most retsinas come from the wine growing regions that dominated the ancient trade: Euboea, Attica, Boeotia and Peloponnisos.
Retsina production has been declining slightly because more growers realize that the exotic, sometimes bitter-tasting Greek speciality, is not always welcomed by foreign palates. There has been a trend to produce lighter retsinas, well-crafted white wines with just a hint of resin (Kochilas 1990).
These include: Alpha pinene Terpene alcohols: Beta pinene Terpineol Camphene Borneol Dipentene Geraniol Maleopimaric acid Linalool Maleic and phenolic resins Modified rosins Metallic resinates
As has already been mentioned, the composition of turpentine can vary considerably according to the species of pine from which it is harvested and this greatly influences its value and end use. The alpha and beta pinene constituents of turpentine are the starting materials for the synthesis of a wide range of fragrances, flavours, vitamins and polyterpene products and form the basis of a substantial and growing chemical industry. The biggest single turpentine derivative is synthetic pine oil, which is used in disinfectants, cleaning agents and other products with a "pine" odour. Other derivatives include isobornyl acetate, camphor, linalool, citral, citronellol, citronellal and menthol and are used either alone or in the elaboration of other flavour compounds (Coppen and Hone 1995).
Table 6.2 Principle uses of turpentine and rosin
Turpentine
Rosin
Chemicals and pharmaceuticals Gums and synthetic resins Paint, varnish and lacquer Products for railroads and shipyards Shoe polish and related materials Rubber Printing inks Adhesives and plastics Asphaltic products Furniture Insecticides and disinfectants
Paper and paper sizing Chemicals and pharmaceuticals Ester gums and synthetic resins Paint, varnish and laquer Soap Linoleum and floor coverings Adhesives and plastics Oils and greases Rubber Printing inks Shoe polish and related materials
Source: Forbes and Meyer (1956).
Production and trade
Total world-wide production of rosin is currently about 1.2 million tonnes annually. Of this total, approximately 720 000 tonnes, about 60 percent, is gum rosin (valued at around US$420 million at first half 1994). Most of the remainder is tall oil rosin (35 percent) and the rest is wood rosin. World production of turpentine currently stands at 330 000 tonnes from all sources. Of this total, almost 100 000 tonnes (30 percent) is estimated to be gum turpentine (valued at US$50 million) and the bulk of the remainder is sulphate turpentine (Coppen and Hone 1995). The United States and China are currently the world’s largest producers and consumers of turpentine. Most United States requirements are presently met by domestic sulphate turpentine production but some gum turpentine is also imported for fractionation and conversion into derivatives. Chinese requirements are met by the country’s own production of gum turpentine.
As labour in the developed countries has become more expensive and fewer workers are willing to undertake the jobs of tapping, gum naval stores production has declined and its centres of production have shifted. During the early 1960s, the United States and former USSR were leading producers of resin and several European countries (France, Greece, Poland, Portugal and Spain) were also major producers (Table 6.3) (Chaudari 1995). Presently, China and Indonesia are leading producers and only one European country, Portugal, is still regarded as a major producer (Table 6.4).
Today the focus of naval stores production is Asia. The People’s Republic of China has been the world’s dominant producer for a number of years. In the early 1980s, Indonesia had a dramatic increase in resin production and today is the second largest producer of gum rosin and turpentine in the world. In 1993, Chinese gum naval stores production accounted for approximately 430 000 tonnes (60 percent) of world gum rosin production; Indonesia accounted for an additional 69 000 tonnes or about 10 percent of world production. Chinese production is unlikely to increase further. However, Indonesia has sufficient area of pine forests available for tapping and the potential to increase production significantly in the future, if it wished to do so (Coppen and Hone 1995). Abnormally high rainfall in Indonesia in 1995 and 1996 led to reduced production in those years but it is hoped that production will recover (personal communication, Coppen, 1997).
The People’s Republic of China and Indonesia also dominate world trade in gum rosin and turpentine. Chinese exports of gum rosin during 1993 was approximately 277 000 tonnes (70 percent of world trade) and Indonesian exports amounted to about 46 000 tonnes. Portugal is the third largest exporter of gum rosin and exports most of its production. A much smaller proportion of turpentine produced in the People’s Republic of China is exported (about 5 500 tonnes). Both Indonesia and Portugal export more turpentine (Table 6.5) (Coppen and Hone 1995).
Resin tapping has become an important industry in a number of developing countries where labour costs are low. In Vietnam, resin tapping is often a women’s enterprise (Fig 6.2). In addition to providing a source of income for women, local resin tapping enterprises also provide an incentive to not over-exploit pine plantations for fuelwood, which is a scarce commodity in this country (Author’s observation). In Cuba, three species of pine, P. caribaea, P. tropicalis and P. cubensis, are tapped for resin. During the period 1989-1993, US$1 028 000 of resin products were exported (Ruiz 1995). In Honduras, resin tapping is conducted in five Departamentos by 29 individual enterprises. During 1993, this industry employed nearly 2 000 people and provided direct benefits to an additional 9 800 individuals (Table 6.6) (Barcenas 1995). In Lithuania, commercial resin tapping started in 1935 and was constantly increasing from 200 tonnes to 1 830 tonnes in 1965. Then it started decreasing to 146 tonnes in 1994. In 1995 resin tapping stopped for economic reasons. The potential resin production by pine tapping in Lithuania is estimated at about 1 500 tonnes per year (Rutkauskas 1998).

In Africa, several countries now produce turpentine and rosin, all of relatively recent origin. Zimbabwe began resin tapping operations in 1976, Kenya in 1986 and South Africa in 1986. Between the three countries, they produce about 4 000 tonnes of crude resin a year (Coppen 1993). Other African countries have extensive areas of untapped pine plantations including Malawi, Uganda, Tanzania and Zambia which have the potential to provide resin and provide employment for a number of people (Coppen and Hone 1995).
RESINS FROM OTHER PINACEAE
Resins from Abies spp.
Abies balsamea is noted for producing a resin rich in terpenes. This resin is known commercially as Canada balsam, Strasburg turpentine, Canada turpentine and balsam of fir. It can be harvested by puncturing and draining resin blisters which form on the smooth bark of young trees with a hollow metal tube about 10 mm in diameter through which the balsam drains into a can.
After purification by straining, the resin is sold as Strasburg turpentine of commerce. It is used in the preparation of finer varnishes, artist colours, etc. A fine oil of turpentine is distilled from the crude material. The residue forms coarse rosin. Canada balsam is a transparent liquid, pale yellowish green in colour and slightly fluorescent. A thin, colourless film is present. It is completely soluble in ether, chloroform, carbon tetrachloride, benzol and turpentine and partially soluble in absolute alcohol, and is used in the manufacture of medicinal compounds and varnish, as a mounting medium in the preparation of microscope slides and for cementing lenses in optical instruments. Canada balsam was of importance in optics because of its refractive index (1.53 for the sodium D lines), being close to that of glass (Tang-Shui Liu, 1971). Collection of liquid resin from bark blisters of Abies balsamea was once an important local enterprise in certain sections of eastern Canada (Harlow and Harrar 1950) but now appears to have declined.
Figure 6.1: Resin collection on Pinus massoniana, Anhui Province, China
Figure 6.2: A woman collects resin from Pinus merkusii, Vinh Province, Vietnam
The Coastal Salish of Vancouver Island, British Columbia, Canada, collected resin from the blisters of Abies grandis. This was rubbed on canoe paddles and other wooden articles. The articles were then scorched to provide a good finish. One group of Coastal Salish mixed the resin of A. grandis and other conifers with venison suet to make an ointment. This was rubbed on the skin to cure psoriasis and other skin problems and as a salve for cuts and bruises (Turner and Bell 1971).
Abies spectabilis, a tree native to the eastern Himalayas, yields a resin that is mixed with oil of roses and applied externally to relieve symptoms of neuralgia
Resins from Picea spp.
Resin collected from Picea abies in Europe was known as Burgundy pitch (Hora 1981).
The indigenous forest dwelling people of north-eastern United States and Canada used the resin exudations from various species of Picea as a chewing gum. Early European settlers to the region quickly adopted this habit. Lumps of spruce gum were sold commercially during the early 1900s making it the first commercial chewing gum sold in the United States. In the Fort Yukon area of Alaska, United States, the Gwich’in Athabaskan Indians chew lumps of resin from Picea glauca. If chewed regularly, it is said to prevent toothaches and headaches (Holloway and Allexander 1990). The Coastal Salish indians of British Columbia, Canada, used gum from Picea sitchensis for chewing and for cementing tools such as harpoons (Turner and Bell 1971).
Resins from various species of Picea have also been used as traditional medicines world-wide. In Uttar Pradesh, India, the resin of Picea smithiana is applied on cracks in heels to promote healing (Singh et al. 1990). In Alaska, United States, the Athabaskan Indians use the resin of Picea glauca to prevent infections in cuts and sores. The resin is heated gently, then poured on cloth, caribou skin or adhesive bandages and applied to the wound. Sometimes the resin is mixed with the foliage of Artemisia frigida to make a poultice for cuts. In the past, pitch was melted onto a large cloth and placed on legs to soothe the pain of arthritis. It was also spread on the chest for a week or more to relieve pain (Holloway and Allexander. 1990).
In the New England States of the United States, local indians used the pitch from several indigenous spruces, Picea glauca, P. mariana and P. rubens, to caulk their canoes (Hussey 1974).
Other resins
Resin once harvested from eastern hemlock, Tsuga canadensis, was known as Canada pitch (Hora 1981).
Small quantities of resin are harvested fromDouglas-fir, Pseudotsuga menziesii. The resin, known as Oregon fir balsam, is collected from felled trees by placing a small drum under the ends of freshly cut logs or from natural wounds by inserting a tube into the wound. This resin is used occasionally in perfumery as a faintly fragrant fixative or in low-cost lemon perfumes for soaps (Good Scents Company 1997).
Indigenous tribes and early European settlers in New England, United States, used resin exuding from the cones of Larix laricina to heal wounds (Hussey 1974).
The resin of Cedrus libani, a tree indigenous to the Near East, was often used in embalming and to coat coffins and papyrus (Chaney and Basbous 1978).
SANDARAC
Sandarac is obtained primarily from the resin of Tetraclinis articulata (synonym - Callitris quadrivalis) (Cupressaceae) (Good Scents Company 1996, Hora 1981), a tree endemic to the mountainous regions of North Africa (Algeria, Tunisia, Morocco) with isolated populations occurring in Malta and near Cartagena, Spain (Vidakovic 1991). An Australian sandarac is produced from various species of Callitris: C. calcarta and C. preissi (=C. verrucosa) (Audas 1952).
The resin is obtained by making incisions in the trunk and branches, causing the viscous sandarac to flow out and quickly solidify when exposed to air. The hardened resin can be then harvested by peeling it from the trees. Sandarac is used in the production of fine lacquers and varnishes (Good Scents Company 1997).
An essential oil can be obtained by steam distillationof this resinor by dissolving the resin in a solution of potassium hydroxide. It is also possible to isolate the essential oil from a neutralized alcoholic solution of sandarac. The alcohol is then evaporated and the alkaline solution is extracted with ethyl ether. After removal of the ether, a small amount of essential oil is left. Sandarac oil is pale yellow or almost colourless and has a slightly balsamic odour (Good Scents Company 1997).
MANILA COPAL
The genus Agathis consists of about 20 species that occur in Australia, south-east Asia, New Caledonia and New Zealand. This genus of Southern Hemisphere conifers, known collectively as Kauri pines, has the most tropical distribution of all of the conifers. A characteristic of the trees of this genus is to exude copious quantities of resin, either spontaneously or from injuries. The resin accumulates on branches, trunks and at the base of trees (Hora 1981). This resin is known in world trade as manila copal (Whitmore 1980). Other names for this product include copal damar, dammara and kauri gum (Hora 1981). Manila copal is white to yellow to dark brown in colour. It hardens with age and eventually becomes brittle. It is soluble in alcohol to a varying degree, has a melting point between 115 and 135o C and is a complex mixture of mono-, di- and sesquiterpenes (Whitmore 1980).
Before wide-scale use of oil-based synthetics, manila copal was an important component of varnishes and, when mixed with linseed oil, was widely used in the manufacture of linoleum. There is still a steady demand for manila copal for specialized uses, for example, varnishes for labels on food tins, for colour prints, as an ingredient in the paint used to paint lines on roads and for fluxes. Besides production for export, there has been a local demand for Agathis resin nearly everywhere trees of this genus are found (Whitmore 1980).
The first production of resin from Agathis spp. was in New Zealand. This was largely the harvest of a so-called fossil gum dug out of the ground, mainly in the Northern Peninsula of the North Island, a region where A. australis occurs (see following section on fossil resins). The New Zealand resin industry reached its peak in 1905 when some 11 000 tonnes were recovered. By 1924, production had declined to 7 000 tonnes and finally ceased in 1950. New Zealand’s "gum lands" are estimated to have yielded a total of 500 000 tonnes of raw material (Whitmore 1980). Today, resin production in New Zealand is of historic interest only.
Production of Manila copal from Agathis dammara, a tropical rain forest species, peaked during the late 1930s and then declined considerably. Before World War II, trade in Manila copal was through Makassar (presently known as Ujungpandang), on the island of Sulawaesi, Indonesia, Ternate, on the island of Halmahera, Indonesia, or Singapore. In 1926, production totalled 18 000 tonnes of which approximately 85 percent came from the Dutch East Indies (now Indonesia) and by 1941, production in the Dutch East Indies increased five times over the 1931 level. During 1936-38, world production was 43 396 tonnes but by 1957-1959, production had dropped by 65 percent to 19 830 tonnes. In 1973, Indonesia exported approximately 2 500 tonnes of Manila copal (Whitmore 1980). See Non-Wood Forest Products Series nr. 6: Gums, resins and latexes of plant origin (Coppen 1995b), p. 64, for more recent data.
Some Manila copal was obtained by probing the ground below Agathis trees with long rods. It was obtained mainly, however, by tapping the tree, usually the bole though in Sabah and New Zealand, cuts were also made on the limbs so that huge, pendulous masses of resin developed. Average annual yields of 10-12 kg/tree can be obtained. Yield increases during the first six months of tapping and, as is the case with pines, resin flow can be stimulated with the application of sulphuric acid (Whitmore 1980).
Manila copal has been an important cash crop for many rural people in the tropical Far East. In response to strong demand from industrial nations, destructive tapping increased production. There were reports of Agathis trees being killed over large areas of Indonesia and attempts were made to introduce controls in the 1930s. Trees respond to intensive tapping by forming cancerous growths. As of 1980, the island of Irian Jaya was the principal Indonesian source of Manila Copal. Trees are utilized only for resin. Small plantations have been established and the Forest Department controls the industry that has developed a non-damaging tapping system. A resin tapping industry is also being developed in the Sepik River drainage in north-western Papua New Guinea (Whitmore 1980).
Copal is one of three non-wood forest products gathered and sold as a cash crop by the Tagbanua, an indigenous group of about 7 000 forest dwelling people on the island of Palawan in the Philippines. As early as the turn of the century, the Tagbanua had become dependent on cash received from the sale of copal, beeswax and rattan to pay off their debts. What had once been a moderate activity, carried out only during the dry season when it was easier to reach sites producing these commodities and agricultural activity was at a low ebb, had become a year round activity. This forced many Tagbanua to abandon their farming activities (Conelly 1985).
Agathis dammara occurs mostly on well-drained slopes at higher elevations on Palawan. Walking time to these sites is from 2 to 5 hours. Collectors use machetes to make incisions in the sides of trees from which the copal resin slowly leaks into sacks. As of mid 1980s, this was a reasonably profitable endeavour, averaging 18 Philippine pesos (approximately US$2.25) per day, more than could be earned by working in agricultural areas (Conelly 1985).
By 1984, collection of copal and the other non-wood forest products on Palawan Island had become so intense that two communities had exhausted their sources of beeswax and copal in the surrounding forest areas. Other factors contributing to the problem was a rapid increase in the Tagbanua population and resource extraction by large-scale mining and logging concessions. Although it is a valuable timber species, logging of A. dammara is illegal. Many trees are cut, however, during the course of road construction and/or land clearing for mineral extraction. One, presumably overly pessimistic, report predicted that the population of A. dammara could be eliminated from the island within a five-year period. Older Tabanua confirm that productive copal bearing trees are becoming more difficult to locate. The productive copal sites, 1-3 hours walk from the villages, are now over exploited. Some trees have died and the remaining are said to produce inadequate amounts of resin. Consequently, copal gatherers must travel to more distant trees in the interior of the island; a 4 to 5 hour walk (Conelly 1985).
MINOR SOURCES OF RESIN
In Brazil, as of the late 1970’s, the resin of Araucaria angustifolia was a locally important material for varnishes, turpentine, acetone and other chemical products (Reitz, et al. 1979).
Resin of Agathis vitiensis, known in Fiji as dakua, is an alternative ingredient to the resin of Canarium harveyi var. harveyi , known as "Fijian glue," a material used in the construction of ocean going canoes. The resin is extracted from pieces of bark by heating the bark in a can over an open fire. The glue is applied hot and the excess is stirred and reheated for later use. A. vitiensis resin is used primarily on the island of Vitu Levu where the tree occurs naturally (Banack and Cox 1987).
FOSSIL RESIN
Amber, or resinite, consists of solid, discrete, organic materials derived from resins of higher plants. These materials are found in coals and other sediments as macroscopic and microscopic particles that have been incorporated into these sediments. The chemical properties of amber are a consequence of both its biological origins and the geologic environment onto which the resin has been deposited and where it has subsequently matured. Various types of amber frequently carry geologic names based on their locality, chemical composition or discoverer. Examples include bitterfieldite, burmite, chemanwinite, glessite, schilerseeite, settlingite, simetite and succinite. As a material of organic origin, amber is unique because of its exceptional preservation, and for the preservation of living organisms within it (e.g. insects, plants parts) (Anderson and Crelling 1995).
The point at which resin becomes amber is a controversial and still unanswered question. Modern resins are continuously deposited into sediments world-wide but have not been considered part of the fossil record. There are products known as "young amber" or "sub-fossil resin" (Anderson and Crelling 1995).
Sources
Resins from both Gymnosperms (conifers) and Angiosperms are known to produce amber. According to Langenheim (1995), five families of conifers and 12 families of Angiosperms are either known or potential sources (Table 6.7). Of the five families of conifers known to produce resin which can eventually become amber, only two families: the Araucariaceae and the Pinaceae, are known to be important sources. There is some evidence that small pieces of amber, deposited in the late Cretaceous and Pliocene Periods, may be derived from the family Taxodiaceae (Metasequioa, Sequoia or Sequoidendron). Mid Eocene amber from Washington State, United States and British Columbia, Canada may have originated from Metasequoia (Langenheim 1995).

Table 6.7 Families of resin producing plants that are sources of amber
Gymnosperms
Angiosperms
Pinaceae* Araucariaceae* Taxodiaceae* Cupressaceae Podocarpaceae
Leguminoseae* Zygophyllaceae Burseraceae* Euphorbiaceae Dipterocarpaceae* Rubiaceae Hamamelidaceae* Guttiferaceae Anacardiaceae* Palmaceae Styraceae Betulaceae
* Good evidence of amber production, for other families, limited evidence. Source: Langenheim (1995).
In most plants of the family Pinaceae, abietane and pimarine diterpenoid acids dominate trunk resins. These compounds tend to be subject to oxidative degradation or dehydrogenation. Consequently, they are not good candidates for production of amber. Members of the family Araucariaceae, on the other hand, contain labdatriene communic acid that readily polymerizes. The conifer genus Agathis is particularly interesting from the standpoint of amber production because it produces resin in great quantity and several species have been tapped for commercial resin production (see previous section on Manila copal).
Agathis spp. may be a significant source of the world’s amber for the following reasons:
Chemical similarities of ambers from different origins and different geographic locations to resin of Agathis australis, a tree which presently occurs in New Zealand.
Several species of Agathis produce copious amounts of resin with diterpenoid labdatrienes that polymerize into durable material, similar to leguminoid genus Hymenaea resulting in massive accumulations of amber.
Several characteristics of Agathis resins suggest involvement of Agathis, or a relative, as the botanical source of the predominant amber Succinite from the Baltic Sea Region of northern Europe.
Amber from Agathis spp. is reported from Australia and New Zealand and Oliocene and Miocene amber deposits in New Zealand have been determined to be derived from the resin of A. australis. In addition, deposits of Agathis-derived amber have been reported from several locations in Austria and France (Langenheim 1995).
It has been hypothesized that the extensive deposits of amber in the Baltic Region of Europe, known as Succinite, may be the result of prehistoric forests of Agathis or an Agathis-like tree. Arguments in favour of this hypothesis include:
The chemistry of Baltic amber is generally similar to that of the resin from extant A. australis in New Zealand.
The Baltic amber deposits consist of massive accumulations with many large pieces. This is similar to the character of amber deposits underneath from extant A. australis forests in New Zealand.
Baltic amber deposits contain fossil evidence of plant life similar to that that occurs in some extant Pacific subtropical-tropical forests where Agathis occurs today.
Arguments against Agathis spp. being the source of Baltic amber include:
Baltic amber contains succinic acid. This compound is absent in extant Agathis resin.
The only resin producing plant parts included in Baltic amber deposits or associated with it are from other coniferous sources.
Wood from the Baltic region with enclosed succinite is considered to be "Pinaceous." Yet pine resins do not have constituents that readily polymerize.
The genus Agathis appears to have been a significant source of amber from the early Cretaceous through the Tertiary in various locations throughout the world, based on chemical evidence, which is corroborated in a few cases with associated plant parts of Agathis. The botanical source of succinite in Baltic amber is an enigma. The possible involvement of Agathis is supported by the considerable chemical similarity of succinite and resin from extant A. australis, the massive accumulation of A. australis resin and Asian and tropical affinities of numerous floral inclusions in the amber. However, the lack of succinic acid in extant Agathis or Agathis plant remains in the amber make this source questionable. The many pinaceous remains in the amber lead to a hypothesis that it could have been derived from an araucarian type ancestor or common progenitor and that the araucarian chemical properties of the resin were carried along with other characteristics as pinaceous plants evolved (Langenheim 1995).
Geographic occurrence
The most extensive deposits of amber (succinite) discovered to date are located in the Baltic Sea region of northern Europe, including portions of Denmark, Norway, Sweden, Germany, Poland, Russia, Lithuania, Latvia and Estonia. A small outlier of Russia, an area called the Samland in the Kaliningrad Oblast has the largest known concentration of Baltic amber. Kaliningrad is believed to have supplied over two-thirds of the world’s amber and 99 percent of the Baltic amber in recent years.
The amber deposits of the Baltic region of Europe have been known since prehistoric times and had a significant influence on early European history. Amber of Baltic origin has been found in Egyptian tombs that date back to 3200 BC, suggesting that barter and trade routes between Egypt and northern Europe were established at that time. Germany, Poland, Lithuania, Latvia and Estonia have Neolithic burial sites in which amber has been included. Amber "The Gold from the North" was a major trade item when the Vikings dominated European Sea trade between 800 and 1000 AD. As amber became an increasingly valuable commodity in the Baltic Region, dukes, kings and Teutonic knights tried to control its collection and sale. Recovery rights were granted and rescinded by the "Amber Lords" as early as 1264 AD. When amber was collected without the supervision of a "Beach Master" or "Beach Rider," the violators were hung. Amber guilds were formed in the fourteenth century to create rosaries and other works of art from material supplied by the Amber Lords.
The most plentiful source of amber outside of the Baltic region is the Dominican Republic. This amber is known as retinite and contains no succinic acid.
Small quantities of amber have also been found in the United Kingdom along the English coast of Kent, Essex and Suffolk. This material is usually golden or cloudy yellow in colour and its plant source is not known.
Several Asian sources of amber are known. Chinese amber is highly favoured because of its reddish colour. Burmite, an amber found in Myanmar, has been used by Chinese craftsmen as early as the Han Dynasty (206 BC to 220 AD). In Japan, amber is found in coal beds. Other sources of amber include Canada, Greenland, Mexico, Romania, Sicily (Italy), Tanzania and the United States.
Uses
The finished products of amber are jewellery, smoking articles, objects of art and religious articles. Jewellery includes necklaces, bracelets, brooches, earrings, pendants, rings, cufflinks etc. Smoking articles include cigar/cigarette holders and mouthpieces for pipes. During the 1920s, about one-half of the production of amber was used for the manufacture of articles for smokers. Objects of art include carvings, jewellery boxes, cups and dishes, writing utensils, ornaments, chess sets, mosaic pictures and chandeliers. Religious items include rosaries and prayer beads, sacred figures and amulets.
Amber is also used in the production of varnish and lacquers. In ancient times, it was burned as incense to camouflage the odour of spoiled food. Fine amber varnish is applied to violins. Balls of amber can be used to remove lint from clothing because of its ability to generate static electricity by rubbing.
Occasionally, plant and animal materials are preserved in amber. These are of great scientific value. Insects and insect remains, in particular, are often found preserved in amber and represent the finest fossil remains of prehistoric insects known. These provide opportunities to study evolution, biogeography, environmental reconstruction and extinction. A range of information about past insect faunas, as well as other plants and animals, of particular global areas, can be extracted from fossil amber. Insects preserved in amber are normally preserved with such clarity that they can be compared in minute detail with closely related groups living today. Amber fossils provide the earliest known records of some insect orders and families plus numerous genera and species. These are important in reconstructing insect phylogenic lines. Insects preserved in amber show irrefutably what characteristics were present at particular times in the earth’s history. They can also provide data on the behaviour of extinct insects, the structures of their biological communities and past symbiotic associations. Fossil amber provides the scientific community with a unique opportunity to discover many details of the past world of small organisms that is unavailable through other types of fossils (Poinar 1993).
_________________________ 12/. Botanists subdivide the genus Pinus into two broad groupings: the soft or haploxylong pines and the hard or diploxylon pines. The soft pines have deciduous needle sheaths, most species have needles in fascicles of five (exception, the piñon pines, which have needles in fasciles of one to three needles), soft, unarmed cone scales and relatively soft white-coloured wood. The hard pines have persistent needle sheaths, most species have needles in fascicles of two to three (rarely five-eight), hard cones scales, mostly armed with spines an dwood that is relatively hard and of a yellowish colour (Harlow and Harrar 1950). 13/. Information provided by Dr. M. P. Shiva, Centre of Minor Forest Products, Dehra Dun, India. 14/. Information obtained from the William Wrigley Jr. Company via the World Wide Web. 15/. Information provided by Gordon Hosking, New Zealand Forest Research Institute, Rotorua, NZ