Abstract
Introduction
Gum naval stores - the production of turpentine and rosin from pine resin
Eucalyptus oil - its production from Eucalyptus leaf
John J. W. Coppen
Natural Resources Institute, Chatham Maritime, Kent ME4 4TB,
United Kingdom
FAO/Commonwealth Science Council Regional Expert
Consultation Meeting on Non-Wood Forest Products, Arusha, Tanzania,
17-22 October, 1993
The production of pine resin (as a source of turpentine and rosin) and eucalyptus oil in different parts of the world is described with the aid of overheads and slides. The social and economic benefits that derive from such activities are noted. Focus is given to their present production in Africa: in Zimbabwe, Kenya, South Africa and Swaziland. In conclusion, the need for research in certain areas - if production is to be improved and extended successfully to other African countries - is discussed.
The term 'Non-Wood Forest Products' embraces a wide range of plant and animal products that may be obtained in one way or another from the flora and fauna growing or living in the forest. It distinguishes non-wood products, or minor forest products as they used to be called, from those such as timber and pulp in which the log of the felled tree is the primary product. The term is often used in connection with traditionally collected products from the natural forest but may be applied equally to those derived from forest plantations or smaller, community or family based plantings.
Two groups of trees that are very widely planted throughout the world, pines and eucalypts, yield products that most certainly fall in the category of 'non-wood forest products': resin obtained by tapping pine trees, which on distillation yields turpentine and rosin, and oil obtained by distilling the leaves of certain Eucalyptus species. The manner in which these products are obtained from the trees, particularly in Africa, the social and economic benefits to be gained from undertaking such activities, problems or gaps in knowledge that exist in meeting the demands of the market or in raising productivity, and the ways in which research needs to be directed in order to provide some answers, are discussed below [and with the use of slides].
Any country with a standing resource of pine trees - whether natural or plantation - has the potential to tap them and obtain a resin which yields, after a process of distillation, turpentine and rosin. These two products enter international trade for eventual use in a wide range of applications, but may also meet important needs of the producing country.
Around 850,000 tonnes of turpentine and rosin are produced annually from tapping pine tress and of this, China accounts for over half. As increasing labour costs have led to a decline in production in countries such as the USA, Portugal, Spain and France, others, such as Brazil and Indonesia, have increased production markedly in recent years to take advantage of the demand for these products.
There are now three producers of turpentine and rosin in Africa, all of relatively recent origin: Zimbabwe (which began tapping about 1976), Kenya (1986) and South Africa (1986). Between them they produce about 4,000 tonnes of crude resin a year. The tapping operation itself is a labour-intensive activity and the employment opportunities thus offered are a major incentive to exploring the potential for naval stores production in a country where none exists. Women can undertake several of the tasks involved. At the national level, gains or savings in foreign exchange can be made through import substitution or exports.
In most countries, older methods of tapping which involve cutting deeply into the wood have been replaced by those which entail simply removing small, horizontal strips of bark at regular intervals and applying a liquid or paste formulation. In this way, the tree is not damaged and the stem, if it is to be felled eventually for timber or pulp, does not suffer any significant reduction in volume or quality. Royalties payable to the Forestry Department or owner of the trees - usually based on the amount of resin collected - provides a valuable source of extra income.
While most pines yield resin of some sort upon tapping, the question of whether it is economic to do so depends on its quality and the quantities that may be obtained. Some generalisations can be made in terms of those species of pine which are most suitable in this regard, although other factors such as provenance origin of the trees and local climatic conditions can have an important influence. Pinus elliottii, P. caribaea and P. radiata are the three species of pine tapped in Zimbabwe, Kenya and South Africa. Countries such as Tanzania, Zambia and Malawi have large areas of P. kesiya, P. oocarpa and P. patula planted. NRI experience is that the first two species are not high yielding in resin, but the good quality of P. kesiya resin and the fact that P. oocarpa is utilised in Honduras and Mexico make them species that are worth investigating in more detail. P. patula, however, is not a species that is ever likely to be exploited for naval stores purposes.
NRI maintains good contacts with the trade and there is no doubt that international demand for turpentine and rosin will remain high for the foreseeable future. Importers and end-users are keen to find new sources, providing price and quality are good. In the first instance, however, new producers will want to meet local demand: turpentine for use by the paint industry as a solvent for paints and varnishes, and rosin for use by the paper industry or for making soap.
The major constraint to increasing production to meet this demand is the shortage of resin. This may be due to the fact that existing production utilises trees that are intrinsically of limited yielding capacity (i.e. they are not the optimum species, variety or provenance), or environmental conditions are not well suited to high resin flow, or the tapping methods used are not optimal. Or there may simply be a shortage of trees, perhaps because replanting is not taking place as fast as trees are felled. Solutions exist for most of these problems, though some are longer term and require investment in research, bath by forestry organisations and institutions, and by agencies that have expertise in these areas. Current work in South Africa on Pinus hybrids holds particular promise for the region.
Better education can also play an important role: heightened awareness amongst foresters and decision makers of the benefits that accrue from gum naval stores production may enable untapped resources to be utilised, whilst the pooling of knowledge among existing and potential producers is to the advantage of bath and is to be encouraged. The case for doing this in Africa is no less strong than elsewhere and, indeed, has already been voiced by producers in the region.
It would not necessary for a new African producer of pine resin to be committed to the installation of a processing plant. Although this may be desirable eventually, crude resin could, in the first instance, be an item of cross-border trade, going some way towards making up the shortfall experienced by existing producers. Kenya, for example, has a requirement of about 1,000 tonnes of rosin for use by the paper industry, but only produces about half of this from its own resources. Countries such as Tanzania, Zambia and Malawi could step in to provide the remainder if the pines were shown to be capable of supporting a tapping operation.
The fast-growing nature of eucalypts makes them ideally suited to the production of wood for pulp, timber (including poles) and fuelwood. They are also, however, an important source of essential oil.
World production of eucalyptus oil is around 3,500 tonnes per year, of which about 2,500 tonnes is the medicinal type of oil. Most of the balance of production is of perfumery-type of oils. China accounts for about 70% of world production of medicinal oil (and the bulk of the perfumery type).
African production of medicinal oil amounts to approximately 250 tonnes and is split between South Africa, Swaziland and Zimbabwe, although the latter provides less than 10 tonnes of this. It is possible that Tanzania will commence production in the near future.
Eucalyptus may be utilised for oil production in one of two ways: it may be grown specifically for oil on a short-rotation coppice system, harvesting the regrowth at intervals of between 6 and 16 months after the first cut; or the 'waste' leaf available after trimming the felled tree destined for the pulp or sawmill may be collected and distilled.
Most of the social and economic benefits that derive from the production of pine resin apply equally to the production of eucalyptus oil. In the case of estate-led production specifically for oil, harvesting of the leaf and loading it on to trailers for dispatch to the distillery is, like pine tapping, labour-intensive. The distillery probably requires rather more people to maintain production (to load and unload the stills) than does a resin distillation plant. In contrast to pine resin, the distillation of eucalyptus oil is something that can be undertaken on a relatively small scale. Stills of 50 kg capacity and less are easily fabricated for village-scale use.
The leaves of most species of eucalypt yield an oil when distilled, but only a few species produce it in sufficient amounts and of a quality to make its distillation practicable and economic. Utilisation of 'waste' leaf, therefore, depends on the species being grown for its wood also being suitable for oil. E. globulus (grown for pulp in Spain and Portugal) and E. citriodora (grown for charcoal production in Brazil) are two such species. In Africa, E. smithii is a particularly fast producer of leaf biomass and is by far the major source of medicinal eucalyptus oil. E. radiata, however, holds much promise as a significant supplementary source of oil in the region.
To date, most African production of oil has bean from trees planted specifically for that purpose. E. camaldulensis (Petford provenance), however, which is suited to more drier areas than E. smithii and E. radiata, has high potential for use as a source of both oil and wood for pole or fuel purposes.
Utilisation of Eucalyptus as a multipurpose tree, as well as meeting a number of different needs, means that the risks associated with low prices or demand for one or other of the products are spread and the effects minimised. Research is needed, however, to define the best harvesting schedule for the species grown so that the returns are maximised. As with pines, other long-term research remains to be done. As well as seeking to increase oil quality and productivity through selection of elite germplasm, improved field management will undoubtedly pay dividends.
