Subsistence farmers in semi-arid West Africa consider trees as an integral part of agriculture. They have for centuries maintained a traditional land use system known as the agroforestry parkland system, in which trees occur in cultivated or fallowed fields.

Through careful tree selection, farmers have deliberately shaped tree production on their farmland to fulfil their specific needs. But the parkland system is not without its challenges.

Products and beneficiaries

Parkland trees provide basic food commodities and traditional medicines. These include a variety of gums, oils, proteins, fruits and drinks that are of nutritional importance for many people, especially in rural areas.

Agroforestry parklands are also a major source of wood and non-wood products, that provides not only firewood, but also household income when sold. Some products, including gum Arabic (Acacia senegal) and shea nuts (Vitellaria paradoxa), even provide export earnings. In some places in West Africa, agroforestry parklands account for up to 75% of total harvests of wood and non-wood products.

Parkland resources also have social and cultural significance. As gathering and processing of parkland products require no cash investment, women, poor people, immigrants and young adults are often involved in these activities.
Women are also mainly responsible for the marketing of these products, and it generates a higher proportion of income for women than men. This helps mothers provide nutritional food for their children. Most often only a few tree species dominate the parklands, but these contribute to the maintenance of many other species with often 40 to 50 trees being cultivated in a cycle.

Scattered trees also fulfil fundamental ecological functions in soil and water conservation and environmental protection. Most of the agricultural production in areas of the Sahel where populations have settled, occurs under the canopy of parkland trees.

Changing tree density

Tree densities in rural landscapes and even in parklands have significantly declined over the years. The drought in the seventies, as well as shorter fallow periods, may have contributed to this. As a result, these landscapes and parklands are often characterised by old trees and a lack of regeneration.

Since trees take a long time to regenerate, the lack of tree density in parklands can further lead tothe degeneration of these systems. However, the decline of parkland cover is not uniform, and pockets of active parkland do exist, probably because some of the rural communities who respect the value of these trees spontaneously maintain and regenerate these parklands to meet their needs and commercial opportunities.

The Parkia biglobosa, that is also grown in a parkland system, provides an income to women who ferment the seeds to produce nététou, a spicy seasoning. (Source: https://www.senenews.com/actualites/societe/le-netetou-condiment-traditionnel-d%E2%80%99afrique-de-l%E2%80%99ouest-entre-dans-la-modernite_11319.html)

Biophysical determinants

Interactions between trees and crops shape the configuration of parkland agroforestry and the way farmers manage the trees in their fields. The reverse cycle of Faidherbia albida that sheds its leaves during the rainy season, is generally responsible or a substantial increase in grain yield if planted underneath these trees.

In contrast, crop performance under species with a typical cycle that bear leaves during the growing season, reduce the crop yield. This is a result for the sun not reaching the growing crops, so photosynthesis is hampered. This can be rectified by pruning the trees to let more sunlight in to reach the crops underneath the canopy.  The soil underneath the trees is usually more fertile, contributing to a higher yield. However, yields also depend on tree size, parkland density, latitude and annual rainfall variability.

Economic incentives

When the farmers perceive that trees and their products gain in value because of increased economic worth, greater demand or declining availability, they are more likely to work actively to protect and replenish trees in parklands. When other activities yield more income, they may neglect the parkland trees. Factors such as markets, pressure on the village resources, migration and relations with urban centres, strongly influence the relative value of parkland trees. For instance, when the price of shea butter increase, regeneration of shea trees is promoted.

If fuelwood prices outperform those of the tree’s other products, trees tend to be felled and sold as fuelwood despite the economic importance as a source of cooking oil. However, where economic incentives and a tradition for conservation of the species exist, these trees are maintained and used for oil production.

Also, where traditional products from parkland trees can be substituted by cultivated crops or items purchased at the market, farmers may be less motivated to regenerate parklands. Shea butter is often substituted by animal butter where livestock is produced. Vegetable oils, such as groundnut and palm oil, are favoured by some groups who prefer these because they are easier to process and they like the taste better. Another product of parkland trees are the seeds of Parkia biglobosa that are fermented to be used as nététou, a spicy seasoning. This traditional product is however facing competition from industrially processed stock cubes, like Maggi.

The shea fruit must be dehulled and the thin layer of flesh removed to get to the nut that is used to produce shea butter. (Source: http://naturalhomes.org/naturalliving/shea-butter.htm)

Research and development

The labour intensiveness and low efficiency of traditional techniques for processing raw materials into edible products, as well as large amounts of water and fuelwood needed for the processes, are hampering production of both products.

A variety of presses have been developed by projects working with shea that have increased the capacity of women’s groups to produce high-quality shea butter in a shorter time. Also, technology to mechanise the dehulling and cleaning stages of the nuts has made the shea process less labour and time consuming.

Commercial opportunities

Commercial opportunities and market systems for parkland products are also being developed to the advantage of the women who are involved with the processing of these products.

The Shea Project in Uganda has developed an association with a natural cosmetics retailer in California that provides a steady international export market. The company offers double the local price for high-quality packaged shea butter, which allows women’s groups to rapidly generate profits after covering the cost of the press. The project also expands domestic market opportunities of traditional cooking oil that is attractively packaged in containers, in major towns of northern Uganda as well as in the capital city Kampala.

The nététou project in Senegal has developed several new related products, such as paste, powder and cubes in sealed clear plastic bags to overcome urban concerns about the hygiene of the traditional preparation process.
Besides the two examples stated, agroforestry parklands also comprise a large variety of other species, of which most are multipurpose and yield several products that are marketable. Even if some tree products do not have market value, they still have cultural and religious value and contribute to environmental functions.

Impact of agricultural policies

Agricultural policies have strongly influenced the evolution of agroforestry parklands in West Africa. Early agricultural development models advocated single cropping in geometrically shaped fields devoid of woody cover. Also, trees of local origin were ignored or regarded as obstacles for animal traction (donkey or ox-drawn ploughs) and mechanisation and the development of intensive and production systems. In some areas, financial credit was only granted when all trees were cleared from fields.

The promotion of cash crops such as cotton, groundnut and maize, often also led to parkland degradation. These crops displaced staple crops like sorghum, millet and cowpea, and replaced traditional soil fertility restoration of fallowing with chemical fertilisers.

Since fallowing is the main practice responsible for tree regeneration, its replacement with chemical fertilisers has generally been detrimental to agroforestry parklands.

Trees are generally eliminated from plots allocated to cash crops, either deliberately or through animal traction. Tree densities are usually lower on farms that use animal traction, but in some areas, densities actually increased where hand-cultivation and donkey or ox traction were used.

Influence of forest policies

National forest policies in the Sahel often do not promote optimal implementation of improved traditional management practices. A key constraint of Sahelian forest codes for parkland management is that all farmland with trees on it is included in the national forest domain falling under state control, unless the land is registered. However, farmers almost never register their land, because they are generally not well informed, and registration is costly.

There are also regulations controlling the use of trees, and as a result, farmers do not carry out basic management like pruning, coppicing or parasite control. Because of a lack of manpower, most forest services are unable to enforce regulations properly.

Source references

Boffa, J.M. (West African agroforestry parklands: keys to conservation and sustainable management (2000) Unasylva 200, Vol. 51.
https://forest-genetic-resources-training-guide.bioversityinternational.org/fileadmin/bioversityDocs/Training/FGR_TG/additional_materials/Boffa_2000.pdf

Mbow, C., Van Noordwijk, M., Luedeling, E., Neufeldt, H., Minang, P.A., Wowero, G. (2013) Agroforestry solutions to address food security and climate change challenges in Africa. https://doi.org/10.1016/j.cosust.2013.10.014 https://www.sciencedirect.com/science/article/pii/S1877343513001449#bib0075