Published Date
NON-WOOD FOREST PRODUCTS 6
FAO - Food and Agriculture Organization of the United Nations
The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
M-37
ISBN 92-5-103757-4
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Although it has had miscellaneous minor uses as a gutta percha substitute, chicle's economic importance has arisen from its use in the manufacture of chewing gum, where it imparts the "chewing" properties to the product. An inferior, little-used "chicle"-type of gum is crown gum.
The United States chewing gum industry was traditionally the major consumer of chicle but as they have moved towards using a greater proportion of synthetic gums, imports of chicle have fallen, and the Far East has become the major market, particularly Japan. In 1930, at the peak of production, over 6 000 tonnes of chicle were imported into the United States. In the period 1963-66, American imports of chicle from Mexico, the leading producer, averaged just over 1 000 tonnes/year. In the three years 1988-90, exports of chicle to the United States from Mexico (Table 30) averaged 10 tonnes.
Imports of chicle, balata, gutta percha and guayule are recorded as a single group in Japanese trade statistics. However, they have been separated, here, into the component gums as judged by the country origins, and data for the period 1988-94 are given in Table 32. Total imports of chicle into Japan are estimated to have been around 800-1 000 tonnes annually in recent years.
In Europe, at least as far as Mexican exports of chicle are concerned (Table 30), Italy has been the major importer. Total annual imports into Italy may amount to 100-200 tonnes.
Other, minor producers include Belize (see Table 31 for exports in 1989 and 1990), Honduras, Venezuela and Colombia.
Family Sapotaceae:
Manilkara zapota van Royen Chicle (gum),
(syn. M. achras Mill., sapodilla, chico,
M. zapotilla Gilly, Achras sapota L., zapote
A. zapote L., Sapota achras Mill.).
M. chicle Pittier Crown gum
M. williamsii Standley Venezuelan chicle
However, it is also widely cultivated for its fruit, both in tropical America and further afield in India, Sri Lanka, Malaysia, Thailand and the Philippines. MORTON (1987) states that in Mexico, 1500 ha are devoted to fruit production, while 4000 ha are grown primarily for chicle.
A larger member of the genus, M. chicle, has been exploited in Belize in a minor way as a source of crown gum, an inferior form of chicle.
Starting about 1 m from the base of the tree, the chiclero makes a series of diagonal cuts up the trunk (climbing to a height of up to 10 m with the aid of ropes), each cut alternating in direction to the previous one so as to form an ascending zig-zag line, down which the latex flows. A common fault in earlier days was to extend the cuts to two?thirds or more round the trunk, which eventually led to the death of the tree. A bag is attached to the tree at its base and the chiclero returns to collect the accumulated latex either later the same day or the following morning.
The tree can only be tapped again when the laticiferous vessels in the bark have been renewed and this may take up to five years or more. Up to three tappings can be carried out.
The freshly collected latex is boiled in an open vessel, with constant stirring, until it reaches a concentration such that when it is poured into wooden moulds and set aside to cool it solidifies. The blocks of chicle are then transported after sale to the factory for further processing.
The economic viability of chicle production from cultivated sources depends on the continued market for chicle as a natural chewing gum ingredient, as well as production factors such as labour costs. If the market can be maintained and production costs can be held stable, then some increase in the area under cultivation can be justified. Providing the price of "cultivated" chicle remains attractive compared with "wild" chicle, the market always prefers to meet its requirements from renewable, sustainable resources rather than from wild trees which become increasingly less accessible.
BOLT, A. (1961) Chicle. World Crops, 13, 58-59.
DUPAIGNE, P. (1979) [Masticatories and tropical fruits] (in French). Fruits, 34(5), 353-358.
EGLER, F.E. (1947) The role of botanical research in the chicle industry. Economic Botany, 1, 188-209.
HUGUET, L. (1952) [The chewing gum tree] (in French). Revue Forestière Française, 4(12), 803-812.
MORTON, J.F. (1987) Sapodilla. pp 393-398. In Fruits of Warm Climates. 505 pp. Miami, USA: JF Morton.
NAS (1981) Natural masticatory substances. pp 191-192. In Food Chemicals Codex. Third edition, 735 pp. Washington, DC: National Academy Press.
SMITH, E.H.G. (1940) Chicle, jelutong and allied materials - a review. Bulletin of the Imperial Institute, 38, 299-320.
TESSIER, A.M., NOLOT, P. and DELAVEAU, P. (1976) [Critical review of the latexes of Apocynaceae, Euphorbiaceae, Moraceae and Sapotaceae used in masticatories] (in French). Plantes Medicinales et Phytotherapie, 10, 203-212.
TESSIER, A.M., NOLOT, P. and DELAVEAU, P. (1977) [Modern masticatories] (in French). Medecine et Nutrition, 13(3), 171-199.
WILLIAMS, L. (1962) Laticiferous plants of economic importance. I. Sources of balata, chicle, gutta percha and allied guttas. Economic Botany, 16, 17-24.
Table 30. Chicle: exports from Mexico, and destinations, 1988-90
(tonnes)
Source: National statistics
Table 31. Chicle: exports from Belize, and destinations, 1989-90
(tonnes)
Source : National statistics
Table 32. Chicle, balata,gutta percha, and guayulea: imports into Japan, and sources, 1988-94
(tonnes)
Source: National statistics
Notes: a "... and similar natural gums in plate, sheet or strip".
b Judged to be main product according to origin.
Before Hevea plantations were developed in Southeast Asia, jelutong was produced and exported for the manufacture of inferior rubber items, in which elasticity was not a prime consideration. With the advent of large-scale rubber production, exploitation of jelutong ceased almost completely. In the 1920s it regained importance as a basic ingredient in chewing gum, sometimes in admixture with chicle, and since then (at least into the 1960s, when WILLIAMS (1963) reviewed it) this has been its main use. It has a consistency comparable to that of chicle, but the additional advantage that its properties also make it suitable for "bubble" gums.
Exports of jelutong from Indonesia for the six years up to 1993 (Table 33) averaged just over 3 600 tonnes/year, with a peak of 6 500 tonnes in 1990. Most, or all of it, has been exported to Singapore and it is not known how much of this has been re-exported to the United States. Some jelutong is exported directly to Japan, and in Europe, Italy is the main importer.
Unlike the other masticatory gums, therefore, there appears to have been some upturn in use of jelutong in the recent past, at least compared with thirty years ago. It remains to be seen whether the downward trend of the last four years continues.
Average FOB export values for raw, pressed and refined Indonesian jelutong were in the range US$ 720-750/tonne in 1993, compared to US$ 980-1 060/tonne two years earlier.
Family Apocynaceae:
Dyera costulata (Miq.) Hook. Hill jelutong
D. lowii Hook. Swamp jelutong
D. costulata is found in the flood-free lowland and upland areas (up to about 800 m), while D. lowii occurs in the low-lying swamplands.
The term jelutong is used to describe both the tree and the coagulated latex. Pontianak is an older term for the coagulated product.
Recognizing the need to abandon such damaging practice, regulations were gradually introduced from the 1930s describing methods based on a "herring bone" system. V?shaped cuts are made in the trunk, commencing at a height of about 1.5 m, with a central, vertical channel leading to a bamboo cup or cloth bag placed at the base of the trunk, into which the latex flows. A narrow strip of bark is removed from the lower surface of the cut and repeated at 2-3 day intervals down the trunk of the tree. In Malaysia, tapping was restricted to trees of 70 cm diameter and greater, on a panel not to exceed half the trunk circumference. Size restrictions on the smaller D. lowii were slightly reduced. Dyera trees have a moderately good bark recovery, although not as rapid as rubber (Hevea brasiliensis) and the same panel may be retapped after a rest period of about two years.
After first straining the freshly collected latex through a fine-mesh sieve, it is coagulated in one of two ways. In the cold method, dilute phosphoric acid is added to the latex, which is then set aside to stand for 3 days; at the end of this time coagulation is usually complete. In the hot method, which usually gives better results, phosphoric acid is added to the latex and the mixture is boiled with stirring; coagulation is usually complete within 2-3 minutes.
Before shipping to the factory for further processing, the initial coagulant is subjected to some preliminary treatment. This usually entails repeated boiling in hot water to remove soluble impurities; the coagulant is then pressed into blocks in readiness for shipment. If there is likely to be some delay before transportation the blocks are stored under water to prevent oxidation, discolouration and mould formation.
SMITH, E.H.G. (1940) Chicle, jelutong and allied materials ? a review. Bulletin of the Imperial Institute, 38, 299-320.
STANISLAUS, P.R. (1955) Jelutong: a Sarawak latex and timber tree. Wood, 20(4), 169.
WILLIAMS, L. (1963) Laticiferous plants of economic importance. IV. Jelutong (Dyera spp.). Economic Botany, 17, 110-126.
Table 33. Jelutong: exports from Indonesia, and destinations, 1988-93
(tonnes)
Source: National statistics
Sorva is traded in the form of large balls or blocks, produced by the tapper from the latex by a process of boiling and coagulation. Further processing may take place either before or after export, although final processing is undertaken by the ultimate consumer industries.
Processed sorva has traditionally been used as a natural base for chewing gum. It competes in this application with other natural masticatory gums such as chicle and with synthetic gums.
Brazil is currently the only supplier of sorva to the market and the decline in international demand is indicated by the downturn in Brazil's exports from 3 500 tonnes in 1978 to an estimated 500 tonnes in 1992 (see Table 34).
In 1978, sorva exports were valued at almost US$ 10 million (Table 34) and for Amazonas State it was the most important export product (and marginally more valuable than Brazil nuts). The most recent value of sorva exports from Brazil is probably of the order of US$ 1.5-2 million.
Brazil has a large chewing gum industry but this, too, is based principally on synthetic gums and there is, therefore, effectively no domestic market for sorva.
Amazonas State has been the centre of Brazilian production, accounting for 90% or more of the total throughout the period 1978-89. Roraima has been the only other source of sorva of any significance and in recent years has accounted for all of the balance.
Recent price data are not available but some FOB export values are included in Table 34. In 1988, the average value of exported sorva was US$ 3 315/tonne.
Family Apocynaceae:
Couma macrocarpa Barb. Rodr. Sorva, sorveira, sorva grande, cumã-açu, leche-caspi
C. utilis (Mart.) Muell. Arg. Sorvinha
C. guianensis Aubl.
All parts of the tree exude a white latex when cut. Until relatively recently the usual practice for collecting the latex was destructive: a single, oblique channel was cut in the trunk to a height of about 1 m and after draining the liquid into a cup the tree was felled. A series of further cuts was then made the entire length of the tree, sometimes including the branches, to obtain additional quantities of latex. This form of sorva harvesting, undertaken by commissioned groups of sorveiros, is not "extractivism" in the sense applied to the non-destructive collection of rubber or Brazil nuts. Instead, the destructive felling of the natural resource parallels that of Aniba rosaeodora, which is felled for rosewood oil production.
During a recent study of selected non-wood forest products in Brazil (COPPEN et al., 1994), traders stated that Couma is now tapped, although much less frequently than rubber; three times a year was claimed by one trader. It was reported that the recommended tapping interval is between 6 months and 2 years in Rondônia.
On returning from the forest, the collector strains the latex to remove any forest debris and then boils it over a fire for a short time to induce coagulation. Alternatively, the latex is first mixed with water, salt added and the mixture left to stand overnight; this initial coagulum is then boiled in water.
The crude sorva is removed from the water and formed into large balls or blocks. These are usually brown on the outside where they are exposed to the air. The sorva is then wrapped in banana or palm leaves and placed in baskets for transportation and sale to the trader or further processor.
In Rondônia, an average of 2.5 litres of latex per tree can be obtained from sorvinha [C. utilis] and the sorveiro can tap up to 14 trees in a day. For "sorva mole" [C. macrocarpa], where the trees are more widely scattered, four trees per day are said to be tapped, producing an average of 20 kg per tree. LESCURE (1990) has stated that 1.5-2.0 litres of latex are obtained on average from one C. utilis tree by tapping and that a skilled man can collect 50-60 kg per day; the frequency of tapping is not stated.
However, any foreseeable increase in the volume of demand for sorva could be met by harvesting of the wild resource. A network of collectors, intermediate market buyers and exporters is in place and there appears to be no immediate pressure on the wild tree resource. Research and development work on sorva production by cultivation in an agroforestry context, either solely for the latex or in combination with fruit production, is therefore difficult to justify. Moreover, the indications are that the economics of production would not be attractive or competitive with the present form of extractivism.
However, if future demand for sorva is judged to warrant the investment in research, technological improvements to the present tapping methods are desirable. Such improvements should be possible by drawing on more recent experience with other latex and resin-yielding species (such as rubber and pine trees), and should be aimed at improving yields and reducing the risk of permanently damaging the trees.
LESCURE, J.P. (1995) [Extractivism in Amazonia. Viability and Development] (in French). Final Project Report. ORSTOM/INPA/Aarhus University.
LESCURE, J.P. and CASTRO, A. (1990) [Extractivism in central Amazonia. An outline of economic and botanical aspects] (in French). Paper presented at UNESCO-IUFRO-FAO Workshop "L'Aménagement et la Conservation de l'Ecosystème Forestier Tropical Humide", Cayenne, 10-19 May.
WILLIAMS, L. (1962) Laticiferous plants of economic importance. III. Couma species. Economic Botany, 16, 251-263.
Table 34. Sorva: production and exports from Brazil, 1978 and 1986-92
(tonnes; US$/tonne)
Source: National statistics (taken from COPPEN et al., 1994, and LESCURE, 1995)
In contrast to rubber, which is an elastic material, gutta percha is non-elastic; it becomes plastic when heated but retains its shape when cooled. The differences between the two materials arise from their different chemical compositions: rubber and gutta percha both contain a large proportion of the polymeric hydrocarbon polyisoprene, but in the former it is the cisisomer while in the latter it is the trans isomer. The presence of trans polyisoprene in balata-like materials originating from tropical America is referred to elsewhere (BALATA and MAÇARANDUBA), and confers on them their non-elastic properties.
Towards the middle of the last century it was discovered that gutta percha had excellent insulating properties which were retained under water, and its most important use was in providing the insulating material for submarine and underground cables. It was also used (as was balata) for the manufacture of golf ball covers and other moulded products. However, the advent of synthetic resins and other, petroleum-based polymeric materials led to the rapid decline in use of the natural material.
In the 1960s, the United States was by far the largest importer of gutta percha; average annual imports from Indonesia over the 10 years 1963-72 were 1 140 tonnes (LOCKHART-SMITH, 1972). Recent US data are not available.
It is not easy to draw conclusions about present day consumption of gutta percha on the basis of trade statistics alone. Gutta percha is not always disaggregated from other non-elastic gums, and although an attempt has been made to do this in the case of recent imports into Japan of "chicle, balata, gutta percha and guayule" (Table 32), the average annual figure of about 970 tonnes for assumed gutta percha imported from Indonesia is much greater than total recorded exports of gutta percha out of Indonesia for the same period (Table 35, annual average 190 tonnes). Furthermore, of these total exports, only 6 tonnes (in 1993) went directly to Japan.
Indonesia is believed to be the largest producer and exporter of gutta percha today, although it is not clear whether the quantities given in Table 35 are a true reflection of the size of this trade.
FOB export values for gutta percha of Indonesian origin have been quite steady for the last three years of data (1991-93): approximately US$ 1 200/tonne. In 1990 it was about US$ 1 900/tonne.
Family Sapotaceae:
Palaquium gutta (Hk. f.) Baillon
Other Palaquium spp., including P. obovatum (Griffith) Engler, P. oblongifolium,
P. oxleyanum Pierre and P. treubii.
Payena leerii (Teys. et Binn.) Kurz
The main gutta percha-yielding trees are found in Indonesia and Malaysia, particularly the islands of Sumatra and Borneo and smaller surrounding ones. However, they occur as far north as the Philippines and mainland Southeast Asia, and as far east as Papua New Guinea.
Palaquium species are amenable to cultivation and plantations were established in Java for gutta percha production as early as the 1890s. Commercial plantations were also being worked in Malaysia in the 1950s, but the last of these ceased operation in 1967. LOCKHART-SMITH (1972) reported that the plantation at Cipetir, West Java, was the only active one in the early 1970s; its status today is not known. Although P. gutta produces the highest quality gutta percha, P. oblongifolium is the species most suited to planting.
Usually these methods entailed making a series of V-shaped cuts in the bark of the tree about 20-30 cm apart, with a central, vertical channel. Most of the latex coagulated in the cuts and was collected by rolling it into small balls along the cuts; the remainder flowed into small cups fixed to the tree. A rest period of at least two years was said to be necessary between successive tappings to keep the tree economically productive. Unlike rubber trees, which contain laticiferous tubes in the bark, Palaquium spp contain irregular cavities which are not connected, and tapping cannot be done in a manner similar to that for rubber.
In plantations, extraction of gutta percha from the leaves of the trees is more productive than collection of latex by tapping. Harvesting is done partly by plucking (about four times a year) and partly by collecting prunings (which comprise leaves, twigs and small branches).
Primary processing of the latex entails pressing the partially formed coagulum into blocks after first softening it in hot water and removing larger pieces of foreign matter. The blocks are then transported to the factory for further processing; if they need to be stored for any length of time before transportation they are best kept under water to avoid spoilage by aerial oxidation.
Extraction of the gutta percha from leaves is briefly described under VALUE-ADDED PROCESSING, since some aspects of it are similar to methods used for further processing of the crude gutta percha blocks.
The gutta percha content of leaves increases with the age of the leaf: results reported in the older literature state about 3% (dry basis) in young leaves, 8% in medium-aged leaves and 10% in old leaves.
Solvent extraction of gutta from harvested leaves follows the same principles as above, but involves pulverized leaf material instead of chopped crude gutta percha. Bleaching earth is added to the hot mixture to remove unwanted leaf pigments.
An alternative method of processing the leaves involves digesting the leaf pulp in hot water, and collecting and pressing the coagulated latex which separates out into blocks.
READER, D.E. (1953) Gutta-percha. Colonial Plant and Animal Products, 3(1), 33-45.
SERIER, J.B. (1986) [Tree secretions] [includes balata and gutta percha] (in French). Bois et Forets des Tropiques, (213), 33-39.
STERN, H.J. (1939) Gutta percha and balata: purification in the factory. The Rubber Age, (Oct.), 245-249 and 258.
TONGACAN, A.L. (1971) Gutta Percha. FPRI Technical Note No. 106. 2pp. Laguna, the Philippines: Forest Products Research and Industries Development Commission.
WILLIAMS, L. (1962) Laticiferous plants of economic importance. II. Mexican chilte (Cnidoscolus): a source of gutta-like material. Economic Botany, 16, 53-70.
Table 35. Gutta percha: exports from Indonesia, and destinations, 1988-93
(tonnes)
Source: National statistics
Balata is sometimes described as the South American gutta percha. Its non-elastic, insulating properties made it, in the past, a valuable export commodity, used for covering submarine and telephone cables, and in the manufacture of machine belting. Its most well-known use was in providing the outer covering for golf balls. Today, its use in Brazil, once the major world source of balata, is limited to a number of small applications such as the manufacture of souvenir figures and surgical implants.
In the 1970s, synthetic substitutes were developed which immediately displaced balata's role in world markets, and this remains the case today. Table 36 indicates that only small or nil amounts of balata have been exported from Brazil in recent years.
The Brazilian domestic market remains a very small one. Balata finds some use in dentistry and for surgical implants. Its most visible application is its use in the cottage crafts industry for making model animals and other figures, mostly for sale to tourists.
Neither domestic nor international markets offer any prospect for substantially increased use of balata.
Brazilian data indicate a steady and severe decline in production over the last 30 years, consistent with world market trends. Production in Pará state, the main source of balata, was almost 1 500 tonnes in 1961. By 1978 (Table 36), total Brazilian production was down to 400 tonnes and by the latter half of the 1980s recorded production was only around 20 tonnes annually; it was 18 tonnes in 1990.
No price information is available on balata.
Family Sapotaceae:
Manilkara bidentata (DC.) A. Chev. Balata,
(syn. Mimusops bidentata DC., balata verdadeira
Mimusops balata Gaertn.) bulletwood tree
Genuine balata comes from M. bidentata although the term balata is sometimes used in a wider sense to include other non-elastic gums such as maçaranduba (from M. huberi) and coquirana (from Ecclinusa balata).
Tapping methods that are now used for balata involve making a series of circular incisions round the trunk of the tree, eventually extending to the lower branches, which the balateiro reaches by climbing. Each circular incision meets a vertical channel, down which the latex flows to a receiver fixed to the tree.
The frequency with which trees can be tapped appears to be very low and dependent on renewal of the bark which has been removed during the first tapping; different sources state this to be only about once every 3-5 years or every 8-10 years. LOPES (1970), citing views expressed by the "patrons" of several commercial operations in Brazil, says that a 15-20 year rest period is necessary. Furthermore, this is only possible for those trees that survive the first tapping - survival rates were reported to be anything between 80% and 25%.
In a similar manner to sorva, the collected latex is boiled in a large galvanized vessel and the resulting coagulated material then removed, washed with cold water and placed in wooden boxes to form blocks. After removal from the boxes, the gum is left for 2-3 days to harden.
Average yields of 18-20 litres of latex per tree have been reported for tapped trees, and in Brazil, in a 6-month period, one person is said to be able to tap 200-300 trees, producing a total of 800-2000 kg of balata (i.e., of the order of 4-7 kg of balata per tree). Reports of balata production in Guyana in the 1930s describe yields of 5 litres of latex (producing 2.5 kg of balata) per tree as being good, although up to five times these yields can be obtained in exceptional cases.
COPPEN, J.J.W., GORDON, A. and GREEN, C.L. (1994) The developmental potential of selected Amazonian non-wood forest products: an appraisal of opportunities and constraints. Paper presented at the FAO Expert Consultation Meeting on Non-Wood Forest Products, Santiago, Chile, 4-8 July.
FANSHAWE, D.B. (1948) Forest Products of British Guiana. Part II. Balata. pp 16-21. In British Guiana Forestry Bulletin No. 2.
LESCURE, J.P. (1995) [Extractivism in Amazonia. Viability and Development] (in French). Final Project Report. ORSTOM/INPA/Aarhus University.
LESCURE, J.P. and CASTRO, A. (1990) [Extractivism in central Amazonia. An outline of economic and botanical aspects] (in French). Paper presented at UNESCO-IUFRO-FAO Workshop "L'Aménagement et la Conservation de l'Ecosystème Forestier Tropical Humide", Cayenne, 10-19 May.
LOPES, J.R. (1970) [Contribution to the Study of the Exploitation of Balata in Amazonia Region] (in Portuguese). 8pp. Ministry of Agriculture, Pará, Brazil.
MORS, W.B. and RIZZINI, C.T. (1966) Latex-yielding plants. pp 1-12. In Useful Plants of Brazil. San Francisco/London: Holden-Day.
OLIVEIRA, F.A., MARQUES, L.C.T. and FERREIRA, C.A.P. (1992) [Non-Wood Products of the National Forest of Tapajos, Santarem, Para, Brazil] (in Portuguese). Preliminary report TCP/BRA/0154/FAO for IBAMA. 20 pp.
SERIER, J.B. (1986) [Tree secretions] [includes balata and gutta percha] (in French). Bois et Forets des Tropiques, (213), 33-39.
STERN, H.J. (1939) Gutta percha and balata: purification in the factory. The Rubber Age, (Oct.), 245-249 and 258.
WILLIAMS, L. (1962) Laticiferous plants of economic importance. I. Sources of balata, chicle, guttapercha and allied guttas. Economic Botany, 16, 17-24.
Table 36. Balata: production and exports from Brazil, 1978 and 1986-92
(tonnes)
Source: National statistics (taken from COPPEN et al., 1994, and LESCURE, 1995)
Maçaranduba, like sorva, has been used mainly for chewing gum manufacture, though in slightly different formulations.
In the 1950s, recorded exports from Brazil, the major producer, were around 300-400 tonnes/year; most of it went to the United States. More recent data (from the early 1980s onwards, including that shown in Table 37) are somewhat incomplete but indicate exports of less than 10 tonnes/year for most years. Unofficial, trade sources indicate that the level of exports in the early 1990s has been around 20-30 tonnes annually.
Levels of exports from other countries in the region, if any, are not known.
Use of natural gums by the Brazilian chewing gum industry is believed to be very small, and no significant shift in this direction is anticipated which would offer prospects for substantial increases in domestic consumption of maçaranduba.
Production in other countries is not known but it is likely to be small.
Family Sapotaceae:
Manilkara huberi (Ducke) Stand./Chev. Maçaranduba
MORS and RIZZINI (1966) regard M. huberi as a synonym of M. elata (Fr. All.) Monac.
In Brazil, traders' perceptions of how the latex is collected in the forest differ (COPPEN et al., 1994). Some believe that earlier, destructive methods of obtaining the latex have given way to those involving tapping, while others explain that, unlike sorva and balata, which can be tapped, maçaranduba is always obtained by first felling the tree. This may be related, however, to the fact that the wood of M. huberi is very resistant to fungal attack and so highly valued as a source of timber.
In Brazil, the final processing and export of maçaranduba, like sorva, is concentrated in the hands of one or two Manaus-based companies. These companies notify traders based in small river towns of their need for certain products. Such traders, in turn, finance extractivists for a period of up to several months to search for the commodity in question. The costs of this search, and of looking after the families whilst the men are away, are met by the middleman as a partial advance payment for the commodity.
As noted above, the timber is also highly valued. Maçaranduba wood is very dense and resistant to biodeterioration, and is used for making railway sleepers.
COPPEN, J.J.W., GORDON, A. and GREEN, C.L. (1994) The developmental potential of selected Amazonian non-wood forest products: an appraisal of opportunities and constraints. Paper presented at the FAO Expert Consultation Meeting on Non-Wood Forest Products, Santiago, Chile, 4-8 July.
LESCURE, J.P. (1995) [Extractivism in Amazonia. Viability and Development] (in French). Final Project Report. ORSTOM/INPA/Aarhus University.
LESCURE, J.P. and CASTRO, A. (1990) [Extractivism in central Amazonia. An outline of economic and botanical aspects] (in French). Paper presented at UNESCO-IUFRO-FAO Workshop "L'Aménagement et la Conservation de l'Ecosystème Forestier Tropical Humide", Cayenne, 10-19 May.
MORS, W.B. and RIZZINI, C.T. (1966) Latex-yielding plants. pp 1-12. In Useful Plants of Brazil. San Francisco/London: Holden-Day.
OLIVEIRA, F.A., MARQUES, L.C.T. and FERREIRA, C.A.P. (1992) [Non-Wood Products of the National Forest of Tapajos, Santarem, Para, Brazil] (in Portuguese). Preliminary report TCP/BRA/0154/FAO for IBAMA. 20 pp.
Table 37. Maçaranduba: production and exports from Brazil, 1978 and 1986-92
(tonnes)
Source: National statistics (taken from COPPEN et al., 1994, and LESCURE, 1995)
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NON-WOOD FOREST PRODUCTS 6
FAO - Food and Agriculture Organization of the United Nations
The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
M-37
ISBN 92-5-103757-4
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying or otherwise, without the prior permission of the copyright owner. Applications for such permission, with a statement of the purpose and extent of the reproduction, should be addressed to the Director, Publications Division, Food and Agriculture Organization of the United Nations, Viale dells Terme di Caracalla, 00100 Rome, Italy.
LATEXES
CHICLE
DESCRIPTION AND USES
Chicle is the coagulated latex obtained from Manilkara zapota, and is produced on a commercial scale in Mexico and certain parts of Central America. Chicle is to be distinguished from sapote gum, the hard, gummy material which forms slowly over the wound made in the tree to obtain the latex, after the latter has ceased to flow. Sapote gum was once used in Peru as a sizing agent for cloth, and as a glue, but it does not enter world trade and is not considered further here.Although it has had miscellaneous minor uses as a gutta percha substitute, chicle's economic importance has arisen from its use in the manufacture of chewing gum, where it imparts the "chewing" properties to the product. An inferior, little-used "chicle"-type of gum is crown gum.
WORLD SUPPLY AND DEMAND TRENDS
Markets
At one time, chewing gum base consisted almost entirely of natural "gums", of which the principal one was chicle. The most important of the other natural gums was jelutong, although smaller quantities of sorva and maçaranduba have also been used. Nowadays, with the advent of cheaper, synthetic resins with suitable properties, demand for the natural gums for use in chewing gum has declined.The United States chewing gum industry was traditionally the major consumer of chicle but as they have moved towards using a greater proportion of synthetic gums, imports of chicle have fallen, and the Far East has become the major market, particularly Japan. In 1930, at the peak of production, over 6 000 tonnes of chicle were imported into the United States. In the period 1963-66, American imports of chicle from Mexico, the leading producer, averaged just over 1 000 tonnes/year. In the three years 1988-90, exports of chicle to the United States from Mexico (Table 30) averaged 10 tonnes.
Imports of chicle, balata, gutta percha and guayule are recorded as a single group in Japanese trade statistics. However, they have been separated, here, into the component gums as judged by the country origins, and data for the period 1988-94 are given in Table 32. Total imports of chicle into Japan are estimated to have been around 800-1 000 tonnes annually in recent years.
In Europe, at least as far as Mexican exports of chicle are concerned (Table 30), Italy has been the major importer. Total annual imports into Italy may amount to 100-200 tonnes.
Supply sources
Mexico is believed to be the biggest producer of chicle, although if the disaggregation of imported chicle and gutta-type products into Japan - and shown in Table 32 - is correct, Guatemala, which has been a significant producer in the past, may recently have surpassed Mexico: estimated imports from the two countries for the period 1988-94 averaged approximately 400 tonnes (Guatemala) and 370 tonnes (Mexico) each year. Exports of chicle from Mexico for 1988-90 are shown in Table 30.Other, minor producers include Belize (see Table 31 for exports in 1989 and 1990), Honduras, Venezuela and Colombia.
Quality and prices
Recent quality and price information on chicle is not available. General requirements of natural masticatory substances, including chicle, are specified in the Food Chemicals Codex of the United States and these detail limits on arsenic, lead and heavy metals.PLANT SOURCES
Botanical/common namesFamily Sapotaceae:
Manilkara zapota van Royen Chicle (gum),
(syn. M. achras Mill., sapodilla, chico,
M. zapotilla Gilly, Achras sapota L., zapote
A. zapote L., Sapota achras Mill.).
M. chicle Pittier Crown gum
M. williamsii Standley Venezuelan chicle
Description and distribution
M. zapota is a tree which reaches a height of 20?25 m in the wild, with a dense rounded or conical crown and a hard timber. It is indigenous to Central America in the region extending from southern Mexico to northern Colombia, but grows best in the Yucatan peninsula, embracing the southern states of Mexico and the northern parts of Belize and Guatemala ? these form the principal chicle-producing areas.However, it is also widely cultivated for its fruit, both in tropical America and further afield in India, Sri Lanka, Malaysia, Thailand and the Philippines. MORTON (1987) states that in Mexico, 1500 ha are devoted to fruit production, while 4000 ha are grown primarily for chicle.
A larger member of the genus, M. chicle, has been exploited in Belize in a minor way as a source of crown gum, an inferior form of chicle.
COLLECTION/PRIMARY PROCESSING
Details of tapping methods used on plantation-grown trees are not known, but in the wild, methods have probably changed little from the early days of production. Contemporary descriptions given by BOLT (1961) are essentially the same as earlier ones by EGLER (1947).Starting about 1 m from the base of the tree, the chiclero makes a series of diagonal cuts up the trunk (climbing to a height of up to 10 m with the aid of ropes), each cut alternating in direction to the previous one so as to form an ascending zig-zag line, down which the latex flows. A common fault in earlier days was to extend the cuts to two?thirds or more round the trunk, which eventually led to the death of the tree. A bag is attached to the tree at its base and the chiclero returns to collect the accumulated latex either later the same day or the following morning.
The tree can only be tapped again when the laticiferous vessels in the bark have been renewed and this may take up to five years or more. Up to three tappings can be carried out.
The freshly collected latex is boiled in an open vessel, with constant stirring, until it reaches a concentration such that when it is poured into wooden moulds and set aside to cool it solidifies. The blocks of chicle are then transported after sale to the factory for further processing.
Yields
At the first tapping, mature wild trees yield about 1 kg (and up to 2 kg) of latex; the second tapping yields about half this quantity, and the third one less still. However, as would be expected, there is considerable tree-to-tree variation, and the older literature describes methods used by chicleros to test whether it would be profitable to tap individual trees. Yield data for cultivated trees are not available.VALUE-ADDED PROCESSING
Further processing (before mixing with other ingredients to form a chewing gum base) entails drying, melting and centrifuging to remove extraneous matter.PRODUCTS OTHER THAN LATEX
The tree is grown widely for its fruit and, where it has been cultivated as an exotic, this is its primary or sole commercial use. Sapodilla wood is strong and durable but felling of the tree is prohibited in Yucatan because of its value as a source of chicle.DEVELOPMENTAL POTENTIAL
Methods for propagation and cultivation of M. zapota are well established for production of fruit, and a large number of cultivars have been developed. Unlike many of the other latex-producing trees discussed in this report there is, therefore, a firm foundation of knowledge and practical experience on cultural aspects on which to build. Furthermore, in Mexico this experience extends to commercial cultivation for chicle.The economic viability of chicle production from cultivated sources depends on the continued market for chicle as a natural chewing gum ingredient, as well as production factors such as labour costs. If the market can be maintained and production costs can be held stable, then some increase in the area under cultivation can be justified. Providing the price of "cultivated" chicle remains attractive compared with "wild" chicle, the market always prefers to meet its requirements from renewable, sustainable resources rather than from wild trees which become increasingly less accessible.
Research needs
Efforts have been made to extract chicle from the leaves and unripe fruits of the tree, but yields have been too poor to make such production economic. Research should focus on ways of increasing yields of latex from the trunk, either by using improved planting stock or through use of better tapping methods:- Populations of trees throughout the natural range of M. zapota should be screened to determine the intrinsic (genetic) variability in latex yield between and within provenances, with a view to identifying high-yielding trees.
- The development of improved tapping methods should include an investigation of the possible benefits of using chemical stimulants to increase yields of latex; such methods have been used to improve rubber yields in Hevea.
SELECTED BIBLIOGRAPHY
ANON. (1967) A note on the market for chicle. 3 pp. Unpublished memorandum of the Tropical Products Institute, London [now Natural Resources Institute, Chatham].BOLT, A. (1961) Chicle. World Crops, 13, 58-59.
DUPAIGNE, P. (1979) [Masticatories and tropical fruits] (in French). Fruits, 34(5), 353-358.
EGLER, F.E. (1947) The role of botanical research in the chicle industry. Economic Botany, 1, 188-209.
HUGUET, L. (1952) [The chewing gum tree] (in French). Revue Forestière Française, 4(12), 803-812.
MORTON, J.F. (1987) Sapodilla. pp 393-398. In Fruits of Warm Climates. 505 pp. Miami, USA: JF Morton.
NAS (1981) Natural masticatory substances. pp 191-192. In Food Chemicals Codex. Third edition, 735 pp. Washington, DC: National Academy Press.
SMITH, E.H.G. (1940) Chicle, jelutong and allied materials - a review. Bulletin of the Imperial Institute, 38, 299-320.
TESSIER, A.M., NOLOT, P. and DELAVEAU, P. (1976) [Critical review of the latexes of Apocynaceae, Euphorbiaceae, Moraceae and Sapotaceae used in masticatories] (in French). Plantes Medicinales et Phytotherapie, 10, 203-212.
TESSIER, A.M., NOLOT, P. and DELAVEAU, P. (1977) [Modern masticatories] (in French). Medecine et Nutrition, 13(3), 171-199.
WILLIAMS, L. (1962) Laticiferous plants of economic importance. I. Sources of balata, chicle, gutta percha and allied guttas. Economic Botany, 16, 17-24.
Table 30. Chicle: exports from Mexico, and destinations, 1988-90
(tonnes)
| Total | |||
| Of which from : | |||
| Japan | |||
| Italy | |||
| USA | |||
| Canada | |||
| Korea, Rep of |
Table 31. Chicle: exports from Belize, and destinations, 1989-90
(tonnes)
| Total | ||
| Of which from : | ||
| Japan |
Table 32. Chicle, balata,gutta percha, and guayulea: imports into Japan, and sources, 1988-94
(tonnes)
| Total | |||||||
| Of which from : | |||||||
| Chicleb | |||||||
| Mexico | |||||||
| Guatemala | |||||||
| Belize | |||||||
| Honduras | |||||||
| Balatab | |||||||
| Brazil | |||||||
| Gutta perchab | |||||||
| Indonesia | |||||||
| Singapore | |||||||
| Thailand | |||||||
| Hong Kong | |||||||
| Otherb | |||||||
| USA |
Notes: a "... and similar natural gums in plate, sheet or strip".
b Judged to be main product according to origin.
JELUTONG
DESCRIPTION AND USES
Jelutong is the coagulated gutta-like material obtained from the latex of wild trees of Dyera species which are indigenous to certain parts of Southeast Asia.Before Hevea plantations were developed in Southeast Asia, jelutong was produced and exported for the manufacture of inferior rubber items, in which elasticity was not a prime consideration. With the advent of large-scale rubber production, exploitation of jelutong ceased almost completely. In the 1920s it regained importance as a basic ingredient in chewing gum, sometimes in admixture with chicle, and since then (at least into the 1960s, when WILLIAMS (1963) reviewed it) this has been its main use. It has a consistency comparable to that of chicle, but the additional advantage that its properties also make it suitable for "bubble" gums.
WORLD SUPPLY AND DEMAND TRENDS
Markets
The United States has traditionally been the major importer of jelutong, although it is almost all shipped via Singapore rather than direct from source. During the period of peak production in the early 1900s, consumption averaged almost 14 000 tonnes annually. For the five years 1957-61, US imports averaged approximately 1 300 tonnes, a ten-fold decrease.Exports of jelutong from Indonesia for the six years up to 1993 (Table 33) averaged just over 3 600 tonnes/year, with a peak of 6 500 tonnes in 1990. Most, or all of it, has been exported to Singapore and it is not known how much of this has been re-exported to the United States. Some jelutong is exported directly to Japan, and in Europe, Italy is the main importer.
Unlike the other masticatory gums, therefore, there appears to have been some upturn in use of jelutong in the recent past, at least compared with thirty years ago. It remains to be seen whether the downward trend of the last four years continues.
Supply sources
In the past, Indonesia (principally Kalimantan) has been the most important supplier, followed by Malaysia (especially Sarawak). Today, Indonesia is believed to be the main source of jelutong, with the level of production indicated by the exports cited above (and Table 33).Quality and prices
. costulata appears to furnish an intrinsically better quality product than D. lowii, although in former times the method of coagulation of the latex and subsequent handling were also important factors; the moisture content of the jelutong was another important determinant. The proportion of gutta-type material is about 20% (on a moisture-free basis), most of the balance being resin.Average FOB export values for raw, pressed and refined Indonesian jelutong were in the range US$ 720-750/tonne in 1993, compared to US$ 980-1 060/tonne two years earlier.
PLANT SOURCES
Botanical/common namesFamily Apocynaceae:
Dyera costulata (Miq.) Hook. Hill jelutong
D. lowii Hook. Swamp jelutong
Description and distribution
Both species grow to be very large trees with a straight trunk, up to 50-60 m tall and 2 m in diameter in fully developed trees. They are widely distributed in the Malay Peninsula, and the islands of Sumatra and Borneo. D. costulata is the only species found in Malaysia and extends into the southernmost part of Thailand. Both species are found scattered throughout Sumatra and Borneo.D. costulata is found in the flood-free lowland and upland areas (up to about 800 m), while D. lowii occurs in the low-lying swamplands.
The term jelutong is used to describe both the tree and the coagulated latex. Pontianak is an older term for the coagulated product.
COLLECTION/PRIMARY PROCESSING
Older, indiscriminate methods of tapping entailed making a series of cuts around the trunk and removing the bark. The trees were retapped above the first cuts approximately every 8 days until the whole of the bark had been removed from near the ground to as high as the tapper could reach.Recognizing the need to abandon such damaging practice, regulations were gradually introduced from the 1930s describing methods based on a "herring bone" system. V?shaped cuts are made in the trunk, commencing at a height of about 1.5 m, with a central, vertical channel leading to a bamboo cup or cloth bag placed at the base of the trunk, into which the latex flows. A narrow strip of bark is removed from the lower surface of the cut and repeated at 2-3 day intervals down the trunk of the tree. In Malaysia, tapping was restricted to trees of 70 cm diameter and greater, on a panel not to exceed half the trunk circumference. Size restrictions on the smaller D. lowii were slightly reduced. Dyera trees have a moderately good bark recovery, although not as rapid as rubber (Hevea brasiliensis) and the same panel may be retapped after a rest period of about two years.
After first straining the freshly collected latex through a fine-mesh sieve, it is coagulated in one of two ways. In the cold method, dilute phosphoric acid is added to the latex, which is then set aside to stand for 3 days; at the end of this time coagulation is usually complete. In the hot method, which usually gives better results, phosphoric acid is added to the latex and the mixture is boiled with stirring; coagulation is usually complete within 2-3 minutes.
Before shipping to the factory for further processing, the initial coagulant is subjected to some preliminary treatment. This usually entails repeated boiling in hot water to remove soluble impurities; the coagulant is then pressed into blocks in readiness for shipment. If there is likely to be some delay before transportation the blocks are stored under water to prevent oxidation, discolouration and mould formation.
Yields
Although there can be significant tree-to-tree variation, and yields of latex also depend on the method of tapping which is used, D. costulata is generally regarded as being a higher latex yielder than D. lowii. D. costulata trees growing in Malaysia have been found to average about 11 litres of latex a month when tapped daily, and to yield about 3.5 kg of coagulated jelutong. Some old studies have found that upward tapping is more productive than tapping in a downward direction.VALUE-ADDED PROCESSING
Further processing entails repeated washing (sometimes with boiling) and drying to bring it to a lower, more consistent moisture content and pressing into sheets. Recent trade statistics for Indonesian jelutong indicate that it may be exported in the raw, pressed, refined or "other" form, but the nature of modern-day refining or other treatment that it may receive is not known.PRODUCTS OTHER THAN LATEX
Apart from minor timber use, there are no other products of commercial value.DEVELOPMENTAL POTENTIAL
Information acquired in Sarawak shows that D. costulata takes nearly 60 years to attain a girth of about 1.8 m, and until it reaches this size yields of latex are such that it is not worth tapping. On this time scale, plantations established for latex production could not possibly be economic. D. lowii has been tested as a plantation crop in Sarawak, and although it reaches a size at which it can be tapped rather more quickly than D. costulata, 30-35 years of age, this is still too long for a tree in which the latex would be the principal product.SELECTED BIBLIOGRAPHY
BROWNE, F.G. (1952) Jelutong. pp 2-6. In Sarawak Forestry Department Leaflet No. 1.SMITH, E.H.G. (1940) Chicle, jelutong and allied materials ? a review. Bulletin of the Imperial Institute, 38, 299-320.
STANISLAUS, P.R. (1955) Jelutong: a Sarawak latex and timber tree. Wood, 20(4), 169.
WILLIAMS, L. (1963) Laticiferous plants of economic importance. IV. Jelutong (Dyera spp.). Economic Botany, 17, 110-126.
Table 33. Jelutong: exports from Indonesia, and destinations, 1988-93
(tonnes)
| Total | ||||||
| Of which : | ||||||
| Raw | ||||||
| Pressed | ||||||
| Refined | ||||||
| Other | ||||||
| Of which to : | ||||||
| Singapore | ||||||
| Japan | ||||||
| Italy | ||||||
| France | ||||||
| Korea, Rep. of | ||||||
| China (Taiwan) | ||||||
| Malaysia | ||||||
| Hong Kong |
SORVA
DESCRIPTION AND USES
Sorva is collected as a milky white latex from the trunks of certain Amazonian Couma species.Sorva is traded in the form of large balls or blocks, produced by the tapper from the latex by a process of boiling and coagulation. Further processing may take place either before or after export, although final processing is undertaken by the ultimate consumer industries.
Processed sorva has traditionally been used as a natural base for chewing gum. It competes in this application with other natural masticatory gums such as chicle and with synthetic gums.
WORLD SUPPLY AND DEMAND TRENDS
Markets
Sorva has now largely been replaced by synthetic gums in chewing gum manufacture and this has led to a drastic decline in demand. The United States used to be the major importer of sorva but the main international market now is the Far East, with some limited interest in Europe.Brazil is currently the only supplier of sorva to the market and the decline in international demand is indicated by the downturn in Brazil's exports from 3 500 tonnes in 1978 to an estimated 500 tonnes in 1992 (see Table 34).
In 1978, sorva exports were valued at almost US$ 10 million (Table 34) and for Amazonas State it was the most important export product (and marginally more valuable than Brazil nuts). The most recent value of sorva exports from Brazil is probably of the order of US$ 1.5-2 million.
Brazil has a large chewing gum industry but this, too, is based principally on synthetic gums and there is, therefore, effectively no domestic market for sorva.
Supply sources
Brazil is the sole world exporter of sorva. National statistics (Table 34) show a five-fold reduction in Brazilian sorva production over a 12-year period, from something of the order of 5 500 tonnes in 1978 to just over 700 tonnes in 1990. Peak production occurred in 1976 (just over 6 000 tonnes), having risen steadily from about 1 500 tonnes in 1960.Amazonas State has been the centre of Brazilian production, accounting for 90% or more of the total throughout the period 1978-89. Roraima has been the only other source of sorva of any significance and in recent years has accounted for all of the balance.
Quality and prices
There are no international specifications for sorva and no formal grading system appears to exist for material which is exported.Recent price data are not available but some FOB export values are included in Table 34. In 1988, the average value of exported sorva was US$ 3 315/tonne.
PLANT SOURCES
Botanical/common namesFamily Apocynaceae:
Couma macrocarpa Barb. Rodr. Sorva, sorveira, sorva grande, cumã-açu, leche-caspi
C. utilis (Mart.) Muell. Arg. Sorvinha
C. guianensis Aubl.
Description and distribution
C. macrocarpa is a tree up to 30 m high. It is the most widely distributed of the species - found in Peru, Venezuela, Ecuador, Colombia and the Brazilian Amazon, particularly Amazonas - and is the main source of sorva. The smaller C. utilis (Amazonas and the upper Orinoco basin, Venezuela) and C. guianensis (eastern Amazonia and the Guianas) are other species that yield a sorva-type latex. Some hold the view that C. guianensis is a synonym of C. utilis.COLLECTION/PRIMARY PROCESSING
Sorva processing and export in Brazil is based in Manaus, a major town on the Amazon. The raw material is collected from intermediary traders based in medium-sized river towns, who in turn commission collection by groups of sorveiros; these make trips of up to three months to find and extract the gum. The trader finances both the expedition and the extractors' families whilst they are away.All parts of the tree exude a white latex when cut. Until relatively recently the usual practice for collecting the latex was destructive: a single, oblique channel was cut in the trunk to a height of about 1 m and after draining the liquid into a cup the tree was felled. A series of further cuts was then made the entire length of the tree, sometimes including the branches, to obtain additional quantities of latex. This form of sorva harvesting, undertaken by commissioned groups of sorveiros, is not "extractivism" in the sense applied to the non-destructive collection of rubber or Brazil nuts. Instead, the destructive felling of the natural resource parallels that of Aniba rosaeodora, which is felled for rosewood oil production.
During a recent study of selected non-wood forest products in Brazil (COPPEN et al., 1994), traders stated that Couma is now tapped, although much less frequently than rubber; three times a year was claimed by one trader. It was reported that the recommended tapping interval is between 6 months and 2 years in Rondônia.
On returning from the forest, the collector strains the latex to remove any forest debris and then boils it over a fire for a short time to induce coagulation. Alternatively, the latex is first mixed with water, salt added and the mixture left to stand overnight; this initial coagulum is then boiled in water.
The crude sorva is removed from the water and formed into large balls or blocks. These are usually brown on the outside where they are exposed to the air. The sorva is then wrapped in banana or palm leaves and placed in baskets for transportation and sale to the trader or further processor.
Yields
Yields of latex obtained by destructive means have been stated to be up to 6 litres from an adult tree of C. macrocarpa. Average production per man-day has been reported to be 15 litres of latex from three trees. More recently, it has been claimed that a C. macrocarpa tree of 50 cm diameter could yield up to 20 litres of latex after felling.In Rondônia, an average of 2.5 litres of latex per tree can be obtained from sorvinha [C. utilis] and the sorveiro can tap up to 14 trees in a day. For "sorva mole" [C. macrocarpa], where the trees are more widely scattered, four trees per day are said to be tapped, producing an average of 20 kg per tree. LESCURE (1990) has stated that 1.5-2.0 litres of latex are obtained on average from one C. utilis tree by tapping and that a skilled man can collect 50-60 kg per day; the frequency of tapping is not stated.
VALUE-ADDED PROCESSING
Further processing (in Manaus) entails digestion of the crude sorva in water, blending of the various lots to produce a more consistent product, and drying to a moisture content of less than 1%; a little wax is added as a preservative. Although plans were made in the early 1970s to produce refined sorva, resin and trans polyisoprene ("gutta") at Manaus from a feedstock of sorva, balata and maçaranduba, the plant for doing this is not believed to have been built.PRODUCTS OTHER THAN LATEX
C. utilis is amenable to cultivation for fruit production and it is grown for this purpose in parts of Amazonas. Some research has been undertaken on this aspect and one Brazilian institution (FCAP, Faculdade de Ciencias Agrarias do Para, in Belém) has a 16-year old trial plot at one of its field stations. However, no research appears to have been carried out on tapping and its effects on fruit production.DEVELOPMENTAL POTENTIAL
The earlier study cited (COPPEN et al., 1994) concluded that although the recent trend was one of marked decline in world markets for sorva, it seemed unlikely that this would continue. Trade sources in Brazil were cautiously optimistic that energetic marketing would lead to a small increase in demand, perhaps to around 800 tonnes/year (but not to historical levels of 3 000 tonnes and more).However, any foreseeable increase in the volume of demand for sorva could be met by harvesting of the wild resource. A network of collectors, intermediate market buyers and exporters is in place and there appears to be no immediate pressure on the wild tree resource. Research and development work on sorva production by cultivation in an agroforestry context, either solely for the latex or in combination with fruit production, is therefore difficult to justify. Moreover, the indications are that the economics of production would not be attractive or competitive with the present form of extractivism.
Research needs
There appears to have been little or no recent systematic research carried out into ways of improving sorva production on a sustainable basis. In the early 1960s, WILLIAMS (1962) carried out tapping trials on C. macrocarpa over a 5-month period. He concluded on the basis of his own work and that of others that it was not economic to recover sorva from this species in a manner analogous to rubber tapping. Furthermore, unlike the rubber tree, bark renewal is very slow and even after several years the channels have not healed sufficiently to allow re-tapping of the original surface.However, if future demand for sorva is judged to warrant the investment in research, technological improvements to the present tapping methods are desirable. Such improvements should be possible by drawing on more recent experience with other latex and resin-yielding species (such as rubber and pine trees), and should be aimed at improving yields and reducing the risk of permanently damaging the trees.
SELECTED BIBLIOGRAPHY
COPPEN, J.J.W., GORDON, A. and GREEN, C.L. (1994) The developmental potential of selected Amazonian non-wood forest products: an appraisal of opportunities and constraints. Paper presented at the FAO Expert Consultation Meeting on Non-Wood Forest Products, Santiago, Chile, 4-8 July.LESCURE, J.P. (1995) [Extractivism in Amazonia. Viability and Development] (in French). Final Project Report. ORSTOM/INPA/Aarhus University.
LESCURE, J.P. and CASTRO, A. (1990) [Extractivism in central Amazonia. An outline of economic and botanical aspects] (in French). Paper presented at UNESCO-IUFRO-FAO Workshop "L'Aménagement et la Conservation de l'Ecosystème Forestier Tropical Humide", Cayenne, 10-19 May.
WILLIAMS, L. (1962) Laticiferous plants of economic importance. III. Couma species. Economic Botany, 16, 251-263.
Table 34. Sorva: production and exports from Brazil, 1978 and 1986-92
(tonnes; US$/tonne)
| Production | ||||||||
| Exports | ||||||||
| FOB unit value |
GUTTA PERCHA
DESCRIPTION AND USES
Gutta percha is the coagulum produced from the latex of certain trees of the Sapotaceae family indigenous to Southeast Asia, particularly those found in the Malay and Indonesian archipelagos.In contrast to rubber, which is an elastic material, gutta percha is non-elastic; it becomes plastic when heated but retains its shape when cooled. The differences between the two materials arise from their different chemical compositions: rubber and gutta percha both contain a large proportion of the polymeric hydrocarbon polyisoprene, but in the former it is the cisisomer while in the latter it is the trans isomer. The presence of trans polyisoprene in balata-like materials originating from tropical America is referred to elsewhere (BALATA and MAÇARANDUBA), and confers on them their non-elastic properties.
Towards the middle of the last century it was discovered that gutta percha had excellent insulating properties which were retained under water, and its most important use was in providing the insulating material for submarine and underground cables. It was also used (as was balata) for the manufacture of golf ball covers and other moulded products. However, the advent of synthetic resins and other, petroleum-based polymeric materials led to the rapid decline in use of the natural material.
WORLD SUPPLY AND DEMAND TRENDS
Markets
Average annual world consumption of gutta percha in the early part of the century (40 years up to 1936) has been stated to be approximately 850 tonnes, of which about 450 tonnes were used for submarine cables, 300-400 tonnes for the manufacture of golf balls, and the remainder for miscellaneous industries such as machine belting (READER, 1953). LOCKHART-SMITH (1972), on the other hand, states that exports of gutta percha and inferior guttas from Singapore averaged nearly 14 000 tonnes annually between 1900 and 1920. By the 1960s/1970s, golf ball manufacture was the only significant end use for gutta percha (and balata).In the 1960s, the United States was by far the largest importer of gutta percha; average annual imports from Indonesia over the 10 years 1963-72 were 1 140 tonnes (LOCKHART-SMITH, 1972). Recent US data are not available.
It is not easy to draw conclusions about present day consumption of gutta percha on the basis of trade statistics alone. Gutta percha is not always disaggregated from other non-elastic gums, and although an attempt has been made to do this in the case of recent imports into Japan of "chicle, balata, gutta percha and guayule" (Table 32), the average annual figure of about 970 tonnes for assumed gutta percha imported from Indonesia is much greater than total recorded exports of gutta percha out of Indonesia for the same period (Table 35, annual average 190 tonnes). Furthermore, of these total exports, only 6 tonnes (in 1993) went directly to Japan.
Supply sources
In past years, Indonesia and Malaysia have been the dominant producers of gutta percha, with minor quantities coming from Thailand and a few other countries in the region. Singapore is often the first destination for exports, which are then re-exported to end-user countries.Indonesia is believed to be the largest producer and exporter of gutta percha today, although it is not clear whether the quantities given in Table 35 are a true reflection of the size of this trade.
Quality and prices
The quality of gutta percha, both in its crude and processed form, depends largely on its hydocarbon (gutta) content, since it is this that confers on gutta percha its thermo-plastic properties. Most of the remaining material is "resin". Gutta percha which has been extracted from leaves by non-solvent methods (see VALUE-ADDED PROCESSING below) contains around 70-75% hydrocarbon and 6-10% resin; the balance is moisture and a few per cent of solid impurities. Fully refined, solvent-extracted gutta percha ("white gutta") contains less than 1% resin.FOB export values for gutta percha of Indonesian origin have been quite steady for the last three years of data (1991-93): approximately US$ 1 200/tonne. In 1990 it was about US$ 1 900/tonne.
PLANT SOURCES
Botanical namesFamily Sapotaceae:
Palaquium gutta (Hk. f.) Baillon
Other Palaquium spp., including P. obovatum (Griffith) Engler, P. oblongifolium,
P. oxleyanum Pierre and P. treubii.
Payena leerii (Teys. et Binn.) Kurz
Description and distribution
Palaquium species are medium to very tall trees. P. gutta is a medium tree, up to 25 m in height and 1.5 m in girth, with small buttresses. Payena leerii grows up to 40 m high.The main gutta percha-yielding trees are found in Indonesia and Malaysia, particularly the islands of Sumatra and Borneo and smaller surrounding ones. However, they occur as far north as the Philippines and mainland Southeast Asia, and as far east as Papua New Guinea.
Palaquium species are amenable to cultivation and plantations were established in Java for gutta percha production as early as the 1890s. Commercial plantations were also being worked in Malaysia in the 1950s, but the last of these ceased operation in 1967. LOCKHART-SMITH (1972) reported that the plantation at Cipetir, West Java, was the only active one in the early 1970s; its status today is not known. Although P. gutta produces the highest quality gutta percha, P. oblongifolium is the species most suited to planting.
COLLECTION/PRIMARY PROCESSING
In the early 1900s, when demand for gutta percha was at its greatest, collection of the latex from wild trees was entirely by destructive means, so as to obtain as much as possible: the tree was felled, the branches lopped off, and a number of wide cuts made through the bark at intervals along the trunk. When it became clear that this was leading to significant losses of forest, such methods were banned and techniques for tapping the living tree were developed.Usually these methods entailed making a series of V-shaped cuts in the bark of the tree about 20-30 cm apart, with a central, vertical channel. Most of the latex coagulated in the cuts and was collected by rolling it into small balls along the cuts; the remainder flowed into small cups fixed to the tree. A rest period of at least two years was said to be necessary between successive tappings to keep the tree economically productive. Unlike rubber trees, which contain laticiferous tubes in the bark, Palaquium spp contain irregular cavities which are not connected, and tapping cannot be done in a manner similar to that for rubber.
In plantations, extraction of gutta percha from the leaves of the trees is more productive than collection of latex by tapping. Harvesting is done partly by plucking (about four times a year) and partly by collecting prunings (which comprise leaves, twigs and small branches).
Primary processing of the latex entails pressing the partially formed coagulum into blocks after first softening it in hot water and removing larger pieces of foreign matter. The blocks are then transported to the factory for further processing; if they need to be stored for any length of time before transportation they are best kept under water to avoid spoilage by aerial oxidation.
Extraction of the gutta percha from leaves is briefly described under VALUE-ADDED PROCESSING, since some aspects of it are similar to methods used for further processing of the crude gutta percha blocks.
Yields
Tapping yields of latex depend on both genetic and environmental factors, as well as the part of the tree which is tapped. In P. oblingifolium, for example, the latex hardens after a few minutes of exposure to the air, and the yield is considerably lower than that from P. obovatum. Cloudy, moist conditions allow the latex to flow more easily than during hot, sunny periods, when there is some loss of water by evaporation. Higher yields are also obtained from the upper portion of the trunk and branches than from the lower part. Yields of gutta percha per tree are also very variable, but about 1.5 kg has been stated to be a good average.The gutta percha content of leaves increases with the age of the leaf: results reported in the older literature state about 3% (dry basis) in young leaves, 8% in medium-aged leaves and 10% in old leaves.
VALUE-ADDED PROCESSING
Preparation of purified gutta percha involves chopping the blocks of crude material into small pieces, removing the resinous ("non-gutta") fraction by dissolution in cold petroleum spirit, and then dissolving the remaining, separated gutta fraction in hot petroleum spirit. This hot extract is drained from any insoluble foreign matter and then allowed to cool, whereupon the purified gutta percha separates out. After separation and distillation of residual solvent the hot, plasticized gutta is rolled into sheets and stored, either in the dark in well sealed tins, or in water.Solvent extraction of gutta from harvested leaves follows the same principles as above, but involves pulverized leaf material instead of chopped crude gutta percha. Bleaching earth is added to the hot mixture to remove unwanted leaf pigments.
An alternative method of processing the leaves involves digesting the leaf pulp in hot water, and collecting and pressing the coagulated latex which separates out into blocks.
PRODUCTS OTHER THAN LATEX
No other products of economic value are believed to come from the gutta-yielding species.DEVELOPMENTAL POTENTIAL
Although recent Indonesian export data show a modest upward trend, there is insufficient information, here, to be able to make an informed judgement as to the developmental potential of Palaquium and gutta percha production. In particular, it is not known whether the gutta percha produced in Indonesia (or elsewhere) comes from plantation or wild sources.SELECTED BIBLIOGRAPHY
LOCKHART-SMITH, C.J. (1972) Market prospects for gutta-percha. Report of the Tropical Products Institute, London [now Natural Resources Institute, Chatham].READER, D.E. (1953) Gutta-percha. Colonial Plant and Animal Products, 3(1), 33-45.
SERIER, J.B. (1986) [Tree secretions] [includes balata and gutta percha] (in French). Bois et Forets des Tropiques, (213), 33-39.
STERN, H.J. (1939) Gutta percha and balata: purification in the factory. The Rubber Age, (Oct.), 245-249 and 258.
TONGACAN, A.L. (1971) Gutta Percha. FPRI Technical Note No. 106. 2pp. Laguna, the Philippines: Forest Products Research and Industries Development Commission.
WILLIAMS, L. (1962) Laticiferous plants of economic importance. II. Mexican chilte (Cnidoscolus): a source of gutta-like material. Economic Botany, 16, 53-70.
Table 35. Gutta percha: exports from Indonesia, and destinations, 1988-93
(tonnes)
| Total | ||||||
| Of which to : | ||||||
| Singapore | ||||||
| USA | ||||||
| Belgium/Luxembourg | ||||||
| Japan |
BALATA
DESCRIPTION AND USES
Genuine balata is obtained as a latex from trees of certain South American Manilkara species, in particular M. bidentata. Like sorva, balata latex is coagulated by boiling and turned into blocks, the form in which it is traded.Balata is sometimes described as the South American gutta percha. Its non-elastic, insulating properties made it, in the past, a valuable export commodity, used for covering submarine and telephone cables, and in the manufacture of machine belting. Its most well-known use was in providing the outer covering for golf balls. Today, its use in Brazil, once the major world source of balata, is limited to a number of small applications such as the manufacture of souvenir figures and surgical implants.
WORLD SUPPLY AND DEMAND TRENDS
Markets
An international market for balata no longer exists. During the 1960s, when Brazil was the main supplier, the United States was the dominant importer. During this period, Brazil exported around 500 tonnes/year to a world market of approximately 800 tonnes.In the 1970s, synthetic substitutes were developed which immediately displaced balata's role in world markets, and this remains the case today. Table 36 indicates that only small or nil amounts of balata have been exported from Brazil in recent years.
The Brazilian domestic market remains a very small one. Balata finds some use in dentistry and for surgical implants. Its most visible application is its use in the cottage crafts industry for making model animals and other figures, mostly for sale to tourists.
Neither domestic nor international markets offer any prospect for substantially increased use of balata.
Supply sources
The extent of balata production today in countries other than Brazil is not known, but it is unlikely to be substantial given the collapse in world markets. Peru, like Brazil, was a significant producer in the 1950s, and in the 1960s and early 1970s Venezuela and Suriname appeared in United States' import statistics as exporting countries for balata.Brazilian data indicate a steady and severe decline in production over the last 30 years, consistent with world market trends. Production in Pará state, the main source of balata, was almost 1 500 tonnes in 1961. By 1978 (Table 36), total Brazilian production was down to 400 tonnes and by the latter half of the 1980s recorded production was only around 20 tonnes annually; it was 18 tonnes in 1990.
Quality and prices
When balata was a significant item of international trade, its quality depended on its "gutta" (trans polyisoprene) content. Commercial balata was said, typically, to contain about 40-50% gutta, most of the balance being resinous material. Genuine balata of Brazilian origin (from M. bidentata) was claimed to be of superior quality, with a gutta content of up to 80%.No price information is available on balata.
PLANT SOURCES
Botanical/common namesFamily Sapotaceae:
Manilkara bidentata (DC.) A. Chev. Balata,
(syn. Mimusops bidentata DC., balata verdadeira
Mimusops balata Gaertn.) bulletwood tree
Genuine balata comes from M. bidentata although the term balata is sometimes used in a wider sense to include other non-elastic gums such as maçaranduba (from M. huberi) and coquirana (from Ecclinusa balata).
Description and distribution
M. bidentata is a tall tree, reaching 30 m or more, and is found mostly in northern Amazonia and the Guianas.COLLECTION/PRIMARY PROCESSING
Traditional methods of collecting the latex have entailed felling the tree and girdling the entire trunk so as to recover as much latex as possible at one time. Such methods are still claimed to be favoured by many balateiros today.Tapping methods that are now used for balata involve making a series of circular incisions round the trunk of the tree, eventually extending to the lower branches, which the balateiro reaches by climbing. Each circular incision meets a vertical channel, down which the latex flows to a receiver fixed to the tree.
The frequency with which trees can be tapped appears to be very low and dependent on renewal of the bark which has been removed during the first tapping; different sources state this to be only about once every 3-5 years or every 8-10 years. LOPES (1970), citing views expressed by the "patrons" of several commercial operations in Brazil, says that a 15-20 year rest period is necessary. Furthermore, this is only possible for those trees that survive the first tapping - survival rates were reported to be anything between 80% and 25%.
In a similar manner to sorva, the collected latex is boiled in a large galvanized vessel and the resulting coagulated material then removed, washed with cold water and placed in wooden boxes to form blocks. After removal from the boxes, the gum is left for 2-3 days to harden.
Yields
As might be expected, latex yields per tree are very variable and not easily predicted, although there appears to be some correlation with bark thickness. Felled trees have been claimed to yield up to 40 litres of latex or 5-8 times as much as a standing tree. Trees which are tapped a second time have been found to produce only a third the quantity of latex obtained from the first tapping.Average yields of 18-20 litres of latex per tree have been reported for tapped trees, and in Brazil, in a 6-month period, one person is said to be able to tap 200-300 trees, producing a total of 800-2000 kg of balata (i.e., of the order of 4-7 kg of balata per tree). Reports of balata production in Guyana in the 1930s describe yields of 5 litres of latex (producing 2.5 kg of balata) per tree as being good, although up to five times these yields can be obtained in exceptional cases.
VALUE-ADDED PROCESSING
Separation of the gutta and resinous fractions of balata is, as far as is known, always carried out in the end-user country and there are few opportunities for value-added processing at source.PRODUCTS OTHER THAN LATEX
Apart from occasional timber use, there has been no other significant exploitation of the balata tree.DEVELOPMENTAL POTENTIAL
The practical difficulties in cultivating and tapping M. bidentata are, if anything, even greater than for Couma spp., the source of sorva. In the absence of any significant market for balata, and the fact that there appear to be no problems in meeting local demand from existing supply sources, at least in Brazil, there is little incentive to undertake research on silvicultural aspects or improved tapping methodologies, and the developmental prospects must be considered negligible.SELECTED BIBLIOGRAPHY
BRULEAUX, A.M. (1989) [Two former products of the Guianese forest: rosewood essence and balata gum] (in French). Bois et Forets des Tropiques, (219), 99?113.COPPEN, J.J.W., GORDON, A. and GREEN, C.L. (1994) The developmental potential of selected Amazonian non-wood forest products: an appraisal of opportunities and constraints. Paper presented at the FAO Expert Consultation Meeting on Non-Wood Forest Products, Santiago, Chile, 4-8 July.
FANSHAWE, D.B. (1948) Forest Products of British Guiana. Part II. Balata. pp 16-21. In British Guiana Forestry Bulletin No. 2.
LESCURE, J.P. (1995) [Extractivism in Amazonia. Viability and Development] (in French). Final Project Report. ORSTOM/INPA/Aarhus University.
LESCURE, J.P. and CASTRO, A. (1990) [Extractivism in central Amazonia. An outline of economic and botanical aspects] (in French). Paper presented at UNESCO-IUFRO-FAO Workshop "L'Aménagement et la Conservation de l'Ecosystème Forestier Tropical Humide", Cayenne, 10-19 May.
LOPES, J.R. (1970) [Contribution to the Study of the Exploitation of Balata in Amazonia Region] (in Portuguese). 8pp. Ministry of Agriculture, Pará, Brazil.
MORS, W.B. and RIZZINI, C.T. (1966) Latex-yielding plants. pp 1-12. In Useful Plants of Brazil. San Francisco/London: Holden-Day.
OLIVEIRA, F.A., MARQUES, L.C.T. and FERREIRA, C.A.P. (1992) [Non-Wood Products of the National Forest of Tapajos, Santarem, Para, Brazil] (in Portuguese). Preliminary report TCP/BRA/0154/FAO for IBAMA. 20 pp.
SERIER, J.B. (1986) [Tree secretions] [includes balata and gutta percha] (in French). Bois et Forets des Tropiques, (213), 33-39.
STERN, H.J. (1939) Gutta percha and balata: purification in the factory. The Rubber Age, (Oct.), 245-249 and 258.
WILLIAMS, L. (1962) Laticiferous plants of economic importance. I. Sources of balata, chicle, guttapercha and allied guttas. Economic Botany, 16, 17-24.
Table 36. Balata: production and exports from Brazil, 1978 and 1986-92
(tonnes)
| 1978 | 1986 | 1987 | 1988 | 1989 | 1990 | 1991 | 1992 | |
| Production t | 407 | 22 | 19 | 21 | 21 | 18 | Na | Na |
| Exports | Na | 5 | - | - | 15 | - | - | na |
Source: National statistics (taken from COPPEN et al., 1994, and LESCURE, 1995)
MAÇARANDUBA
DESCRIPTION AND USES
Sometimes described as an inferior balata, maçaranduba is collected as a latex from trees of the same genus as genuine balata (Manilkara).Maçaranduba, like sorva, has been used mainly for chewing gum manufacture, though in slightly different formulations.
WORLD SUPPLY AND DEMAND TRENDS
Markets
With the development of synthetic gums for making chewing gum, the international market for maçaranduba has declined sharply.In the 1950s, recorded exports from Brazil, the major producer, were around 300-400 tonnes/year; most of it went to the United States. More recent data (from the early 1980s onwards, including that shown in Table 37) are somewhat incomplete but indicate exports of less than 10 tonnes/year for most years. Unofficial, trade sources indicate that the level of exports in the early 1990s has been around 20-30 tonnes annually.
Levels of exports from other countries in the region, if any, are not known.
Use of natural gums by the Brazilian chewing gum industry is believed to be very small, and no significant shift in this direction is anticipated which would offer prospects for substantial increases in domestic consumption of maçaranduba.
Supply sources
Table 37 indicates a general decline in Brazilian production over the last decade or so, and by 1990 it was only just over 100 tonnes. Data from earlier years suggest that production peaked in 1965, at around 1 000 tonnes. Since 1982, all recorded production of maçaranduba in Brazil, like balata, has come from Pará state.Production in other countries is not known but it is likely to be small.
Quality and prices
Maçaranduba has a lower trans polyisoprene (gutta) content than genuine balata, about 25%, and this accounts for its description as inferior balata. Its value (and price) is therefore assumed to be lower than that of balata and this is borne out by Brazilian export values for consignments shipped in the early 1980s: the unit value of balata was approximately 1.5-2.0 times that of maçaranduba.PLANT SOURCES
Botanical/common namesFamily Sapotaceae:
Manilkara huberi (Ducke) Stand./Chev. Maçaranduba
MORS and RIZZINI (1966) regard M. huberi as a synonym of M. elata (Fr. All.) Monac.
Description and distribution
M. huberi, which is generally considered to be the source of maçaranduba, is a tall Amazonian tree, up to 40 m or more in height.COLLECTION/PRIMARY PROCESSING
Methods of collection of maçaranduba are the same as those described earlier for balata, and primary processing is performed in the same way as for sorva and balata, with the latex being turned into balls and blocks.In Brazil, traders' perceptions of how the latex is collected in the forest differ (COPPEN et al., 1994). Some believe that earlier, destructive methods of obtaining the latex have given way to those involving tapping, while others explain that, unlike sorva and balata, which can be tapped, maçaranduba is always obtained by first felling the tree. This may be related, however, to the fact that the wood of M. huberi is very resistant to fungal attack and so highly valued as a source of timber.
In Brazil, the final processing and export of maçaranduba, like sorva, is concentrated in the hands of one or two Manaus-based companies. These companies notify traders based in small river towns of their need for certain products. Such traders, in turn, finance extractivists for a period of up to several months to search for the commodity in question. The costs of this search, and of looking after the families whilst the men are away, are met by the middleman as a partial advance payment for the commodity.
Yields
There is very little published information on yields from M. huberi. OLIVEIRA et al. (1992) state that tapping is carried out at intervals of two years, yielding an annual equivalent of 1 kg of maçaranduba per tree.VALUE-ADDED PROCESSING
As was indicated for balata, no value-added processing is believed to have ever been carried out at source on maçaranduba.PRODUCTS OTHER THAN LATEX
The fruits of M. huberi are edible and are sometimes found in local markets (in Belém, in Brazil, for example).As noted above, the timber is also highly valued. Maçaranduba wood is very dense and resistant to biodeterioration, and is used for making railway sleepers.
DEVELOPMENTAL POTENTIAL
The poor market prospects for maçaranduba and the low yields of latex obtained (at infrequent intervals in its native state), mean that M. huberi has very little potential in developmental terms. It is unlikely that any investment in research would lead to a more favourable conclusion.SELECTED BIBLIOGRAPHY
ALTMAN, R.F.A. (1955) [Analysis of maçaranduba latex from Manilkara huberi] (in Portuguese). Boletim Tecnico do Instituto Agro Norte, 31, 81-95.COPPEN, J.J.W., GORDON, A. and GREEN, C.L. (1994) The developmental potential of selected Amazonian non-wood forest products: an appraisal of opportunities and constraints. Paper presented at the FAO Expert Consultation Meeting on Non-Wood Forest Products, Santiago, Chile, 4-8 July.
LESCURE, J.P. (1995) [Extractivism in Amazonia. Viability and Development] (in French). Final Project Report. ORSTOM/INPA/Aarhus University.
LESCURE, J.P. and CASTRO, A. (1990) [Extractivism in central Amazonia. An outline of economic and botanical aspects] (in French). Paper presented at UNESCO-IUFRO-FAO Workshop "L'Aménagement et la Conservation de l'Ecosystème Forestier Tropical Humide", Cayenne, 10-19 May.
MORS, W.B. and RIZZINI, C.T. (1966) Latex-yielding plants. pp 1-12. In Useful Plants of Brazil. San Francisco/London: Holden-Day.
OLIVEIRA, F.A., MARQUES, L.C.T. and FERREIRA, C.A.P. (1992) [Non-Wood Products of the National Forest of Tapajos, Santarem, Para, Brazil] (in Portuguese). Preliminary report TCP/BRA/0154/FAO for IBAMA. 20 pp.
Table 37. Maçaranduba: production and exports from Brazil, 1978 and 1986-92
(tonnes)
| Production | |||||||||||||||
| Exports | |||||||||||||||
Source: National statistics (taken from COPPEN et al., 1994, and LESCURE, 1995)
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