Gnetum domestication for livelihood improvement and conservation

Charles Tekwe, Nouhou Ndam and Joseph Poteh Nkefor 1


Gnetum (Gnetum africanum and G. buchholzianum), is a climbing vine in the tropical rainforest of West and Central Africa. The leaves are highly valued as a nutritious green vegetable and today, as an article of considerable cross-border trade, extending to Europe and America. This trade has recently increased drastically into a multimillion dollar trade involving a wide range of people resulting in significant increased in the demand for the species from the wild. This increase in demand, coupled with the absence of a good management system, seriously threatens the resource base. This is mainly as a result of poor harvesting practices, over-exploitation, and the gradual replacement of the habitat in which the species thrive. If nothing is done, Gnetum will not continue to be a source of livelihood to thousands of people, most of whom are women.

This paper sets out to share the efforts of Limbe Botanic Garden to save the two species of Gnetum through developing systems that will permit its cultivation by local farmers. Silvicultural practices were developed for the species, and rural farmers trained and this has led to integration of the species into existing agroforestry systems. Gnetum produced from farms will contribute to maintaining the Gnetum trade, ensure the flow of benefits to the rural poor, and reduce the pressure on the wild population. A gene bank has been established to support the domestication process.

However, to ensure sustainability of the species, the domestication programme needs to go along with the development of sustainable management systems for the wild population, and the enactment of an effective legal system to guide the harvesting and trading of the species. Certainly, experiences from the domestication process would inform this process. In this way Gnetum can continue to be a source of livelihood for the many people that depend on it.

1. Introduction

Gnetum africanum Welw. and G. buchholzianum Engl. generally called Eru are non-timber forest species whose leaves are edible as vegetables. The two species occur in S.E. Nigeria, Cameroon, Central African Republic (CAR), Gabon, Congo, Democratic Republic of Congo and Angola (Lowe 1984, Mialounda 1993). In Central African Republic, Gabon, Congo, DR Congo, and Angola the two species are locally called koko (Bahuchet 1990). In the Anglophone Cameroon, they are known as Eru, while in the Francophone Cameroon they are known as okoko. In Nigeria the two species are called ukasi by the Igbo tribe, while the Efik/Ibiobo call them afang (Shiembo 1998). These two species are very similar and can only be distinguished by the shape of the leaves and character of the male reproductive parts (Lowe 1984, Carlquist & Robinson 1995). For commercial purposes, the two species are not distinguishable.

2. Importance of Gnetum

The leaves of Gnetum africanum and G. buchholzianum are highly valued as a nutritious green vegetable across Centre and West Africa (Shiembo 1998). Traditional dishes prepared with these leaves have provided the cultural identity for some tribal groups in this region. The traditional harvesting practices posed no threat to the resource base, but of recent, these species are an article of considerable cross-border trade. This multimillion trade with Gnetum leaves has significantly increased their exportation to European countries and America where Africans resident in those countries consume it. The upsurge in demand has mounted enormous pressure on the wild population thereby threatening its continuous existence. The species has completely disappeared in some areas where it used to be commonly found.

Gnetum leaves are values as a tasty vegetable when finely shredded and incorporated into soup or stew, or made into condiments, or even taken raw. Nutritionally, Gnetum is very rich in proteins and minerals. The leaves contain high nutritional values as both species contain eight essential amino acids in significant quantities (Mialoundama 1993). This suggests the potential role of these species in the fight against malnutrition in poor rural areas with limited sources of meat. In areas where local population depends on a dwindling wildlife population as a source for protein intake, Gnetum provides an affordable alternative to maintain the nutritional values of their meals. Today, dishes based on Gnetum leaves are prominent on the menu list in many restaurants in Centre and West Africa, and in special eating places offering African dishes in Europe and USA.

The socio-economic value can not be over-emphasised. Dishes prepared of Gnetum leaves gives the cultural identity of some tribes in this region. For example the Bayangi in Cameroon that consider their traditional meals prepared with Gnetum leaves as very unique to them.

Economically, Gnetum leaves sustain an active cross-border multimillion trade stretching from West and Centre Africa to Europe and America. This provides employment to a wide range of persons, most of who are women. Most of the middlemen are young adults whose major source of income is from Gnetum trade (Nkefor 2000; unpublished report). In a single local market in Limbe, Cameroon, Gnetum trade has an annual turnover of over one hundred thousand US dollars. While at a border market - Idenau, the turnover is in the tone of one million US dollars. Fundamentally, thousands of people depend on the harvesting and marketing of Gnetum leaves for their living - women constitute more than 80 percent (Nkefor, 2000).

Gnetum as an economic crop has an important role to play in the fight against rural poverty. If compared with other highly valued forest products as timber, Gnetum trade touches the life of more people in the rural areas. It generates income for a wide range of people in the villages who otherwise are left out from benefiting from exploitation of the forest. It provides jobs for the youths that are involved at all stages of the process - harvesting, loading, transportation etc. Women dominate the marketing of Gnetum leaves in both internal and cross-border markets. For the rural woman it provides an opportunity for her to earn money that contributes in the well being of her household. The marketing of this product in local markets has so far not attracted government interest hence, is not taxed.

Medicinally, Gnetum africanum is used in the treatment of a variety of illnesses. In Nigeria the leaves are used for the treatment of enlarged spleen, for sore throat and as a cathartic (Ndam et al 2000). In Ubangi (DR Congo), it is used to treat nausea and is considered to be an antidote to some form of poison (Burkill 1994). In Congo - Brazzavile, the leaves of both species are used as a dressing for warts and boils, a tisane of the cut-up stem is taken to reduce pains at childbirth (Bouguet 1969).

3. Nature of threat to Gnetum resource base in the wild

The both species of Gnetum in their natural habitat are seriously under threat of disappearing. This is mainly due to the following causes: a) current harvesting practices are destructive; b) current off-take level is more than what the forest can naturally replenish; c) the habitat is converted into other uses such as agriculture; d) the lack of an effective legal framework for the management of NTFPs; and e) the lack of a good management systems for the wild population of the species.

Gnetum africanum and G. buchholzianum thrive in a wide range of habitats, including farm fallows, secondary forests, and closed forest. The vines of both species need support to climb on such as small and big trees, saplings, shrubs, other climbing vines, and other types of materials where they grow to produce quantities of leaves (Shiembo 1994). In the wild, the species grow and form underground tuber or root that forms food reserves. The underground tuber can remain alive for so many years when the vegetation and the Gnetum vines above have been cleared and the surface soil is laid bare.

The harvesting of the leaves involves cutting the whole plant from the base, or completely uprooting, and then the vines are pulled down from the canopy. The vines are then stripped of their leaves and bailed into bundles for transporting by buses to the various markets. In most cases, the harvesting completely eliminates the plant and sometime the underground tuber that has the potential of regenerating is damaged and later attacked by fungal infection or root rot disease (Shiembo 1994), which completely kills it. Hence the current harvesting practices do not encourage the growth and supply of future Gnetum leaves (regeneration). This harvesting practice is destructive and is the major cause for the shrinking population of Gnetum in the wild.

The amount of Gnetum taken out of the forest now is more than what the forest can naturally replenishes. In some cases, the harvesters will completely exhaust an area of the species before moving on to another area. In other areas, much of the forest in which Gnetum grows is being degraded or converted into other uses. This includes uncontrolled timber exploitation, road construction, farming and other forms of economic development. Farming practices that involves slash and burn totally destroys the underground tuber, hence reduces the chances of any re-growth of the Gnetum vine in the area. In these situations the areas will require some active interventions if Gnetum is to grow there again.

In Cameroon, the forestry legislation allows the harvesting of both species of Gnetum for household consumption for free. Harvesting for commercial purposes attracts some taxes through a special permit that is obtained from the relevant government ministry. The permit is for one year and specifies the volume. This fails to specify where this volume should be obtained and what practices must be respected in obtaining the required volume. What prevails on the field is exploiters totally exhaust the areas where they can find the leaves in other to make-up the volume. The volume allocated to harvesters has no bearing on the amount that can be sustainably taken out of the forest without damaging it. This is partly due to the fact no inventory has been conducted to know what is available and very little research has been done to develop off-take levels. Most governments are still grappling with this to come up with what can be recommended as sound management systems for most of the NTFPs in the wild.

4. Efforts towards the domestication of Gnetum

As Gnetum species become increasingly endangered as a result of the poor harvesting practices, over-exploitation and erosion of the habitat, there is growing concern from the local population on the scarcity and difficulties to find the leaves. This has drawn some conservation concerns and independently, several initiatives have been started in some countries geared towards domesticating the two species of Gnetum. These initiatives have registered varying degree of success and today, it is certain that Gnetum can be successfully domesticated and with a high potential of being integrated into existing farming systems.

The Limbe Botanic Garden, Cameroon, has over the recent years dedicated a lot of resources towards understanding the requirement for domestication of the two species of Gnetum, and training of local farmers to be able to take-up this new technology. This involves developing methods of propagating Gnetum in farm situations, transfer cultivation methods to farmers, monitoring of farm harvest, consumption, and marketing of the Gnetum from the farm and the establishment of a gene bank to support the domestication process.

4.1. Development of methods for propagating Gnetum spp for cultivation

Limbe Botanic Garden has developed methods for the propagation and cultivation of the two species of Gnetum. This involves researching how best to produce seedling, understanding the performance of variety of genotype under different soils and light (shade) conditions. The results have been very positive and indicate that it is easier to produce seedlings from cutting than from seeds. Gnetum will grow better under shaded conditions - shade tolerant. Different techniques have been developed to suit different growers - on farms and gardening set-ups. Emphasis has been more towards producing a technology that is simple, affordable and acceptable to farmers - to enable the cultivation to be integrated into the existing farming systems. Gnetum cuttings rooted very well with the use of a propagator constructed with easily available materials (Indian Bamboo, polythene plastic and nails). Farmers can easily afford these materials.

4.2. Transfer of cultivation techniques to farmers

The emphasis of the domestication process was to develop a technology that can be integrated into the existing farming systems. The Gnetum produced on the farms will supplement that harvested from the wild to feed the home and international markets. This will reduce the pressure on the wild population and also ensure that benefits reach the rural poor. Selected pilot farmers received a two-week training on the technology and this led to the establishment of pilot farms. The selection of pilot farmers and the pilot sites was with the agricultural extension staff. At each pilot farm a propagator was constructed to produce seedlings to serve a number of farmers. Three different staking conditions - life woody stake, dead stake, and no staking was experimented. Monitoring of the performance of Gnetum plants was monthly with the participation of the farmers and the agricultural extension staff.

The trial plots registered over 90% survival rate. Gnetum with stakes performed better than that without stake. No difference in performance was registered between life and dead staking. A planted Gnetum plant can produce about 1.9kg of leaves every six months. The Gnetum produced through cultivation taste the same as that from the wild and can be traded. Farmers are now beginning to experiment on their individual farms with the cultivation of Gnetum. Other farmers are today visiting these pilot farms. So far the supply of Gnetum leaves from the farm is relatively very low compared with what comes from the forest. A manual was also produced on how to cultivate Gnetum for the farmers and the extension workers.

4.3 Establishment of a gene bank of Gnetum spp from different provenances.

The habitat in which Gnetum grows is gradually disappearing and the species becoming very scarce to find. The need to create a gene pool from the wild population was identified. This will provide opportunities in the selection of high performance taxa for the domestication process. The selection is for characteristics such as leaf size, colour, texture, and flavour. The careful selection of the more favourable genotypes will determine the cultivation success and market desirability of the Gnetum from the farm. The pool will ensure supply of diverse germplasm and the conservation of a viable population at the domestication level. The creation of this gene bank is an on-going process as new provenances are introduced as funds are made available. So far 19 provenance have been collected, all within Cameroon, and planted in the Limbe Botanic Garden. There is limited and requires that similar initiatives in countries where Gnetum naturally occurs so that the genetic variation can be secured. Funding remains a limiting factor to the realisation of this initiative.

Discussion and Conclusion

It is certain that Gnetum is not just another climbing vine in the tropical forest of Africa - it is a source of living to thousand of people stretching from Central and West Africa to Europe and America. The pressure on the wild population of Gnetum from increased demand for commercial purposes is eminent. The trade presence a huge opportunity if the threats can be managed. Cultivation provides a feasible approach to manage some of the threats. Cultivation of Gnetum is possible, and can be integrated into existing agroforestry farming systems to increase Gnetum production to meet this increased demand by the market. This will generate income for rural farmers thereby contributing to the reduction of rural poverty.

However, there is still need to develop sustainable management systems for the Gnetum population in the wild. A more supporting and effective legislation is still required in most of the countries where Gnetum naturally occur. More work still needs to be done to create gene pools for the two species in other countries.

The multimillion trade in Gnetum leaves provides employment to a wide range of people, mostly women, and has a place in the fight against malnutrition and poverty alleviation. Certainly, today Gnetum is a source of life to many, and with a little more effort towards its conservation, it can continue to support the thousand it already does - giving more meaning to the tropical rainforest.


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1 Former Programme Manager, Mount Cameroon Project, Limbe, Cameroon. ctekwe@yahoo.com