Urban and peri-urban forests in sub-Saharan Africa: The Sahel

E.H. Sène

El Hadji Sène is Chief of the Forest and Wildlands Conservation Branch of the Forest Resources Division. FAO Forestry Department.

There is a growing awareness in Africa of the need for peri-urban woodlands and parks to satisfy physical and material needs and for leisure and recreation. This need is changing in accordance with African urbanization which, from a modest 18 to 21 percent between 1950 and 1970, jumped to 32 percent in 1984. The limitations on forest management and sustainability still prevent maximum leisure and recreational use but the situation is rapidly improving, as is forestry's capacity to provide urban populations with products, employment and income.

The development of peri-urban forests in Sahelian Africa

Africa is a "young" continent; the traditional links between populations and their environment, particularly the trees and forests, are very much alive; considering both their food and commodity as well as their spiritual and cultural aspects. These links influence and will continue to influence strongly the provisions and measures introduced by modern administrations to define the status and role of trees and forests in and around urban areas.

The evolution of traditional links

The link between trees and forests and inhabited areas varies according to ecological conditions. In countries characterized by closed forests, the traditional housing pattern was one of dispersed units; the establishment of a village was generally at the expense of trees and woodland. Most villages or small towns in forest areas are conspicuously short of or devoid of trees which are not really felt to be needed, as they are oppressively present in the surrounding environment.

Trees in a large Senegalese Village. Trees form an important part of settlements in the Sahel, regardless of the extent of urban development

The situation, however, is different in open forests, savannahs and steppes. Trees have played an important symbolic role in the establishment of ancestral villages in the Sahelian and Sudanese zones. A tree or cluster of trees was considered propitious for settlement, whether as evidence of water availability, land fertility, abundance of game or simply as a parasol that allowed restful shelter. The names of many towns and large villages in the Sahel stem from trees.

Once the villages have been established, the neighbouring forest serves for agricultural, hunting, fuelwood and medicinal purposes. The spiritual needs of meditation and hidden recesses for initiation rites are the best guarantees of forest conservation near human settlements, which explains the common existence of forest remnants near towns. It also explains the continued existence of trees that no longer fit in a completely urbanized space and environment. A certain tamarind tree (Tamarindus indica) was long venerated in the centre of Kaolack in Senegal, for example. When it died, its stump was left for many years to wear away slowly and naturally.

Trees planted as a visual barrier around a cement factory at the edge of Dakar, Senegal, note the baobab in the foreground

Trees also have an economic role. They are never cut down in the Sahel, where there is a direct dependence on their products for food. The baobab, the shea tree, the borassus (Borassus aethiopum) and the doum palm (Hyphaene thebaica) signal the presence of African villages from afar. The location of old and now-vanished villages is also indicated by clusters of baobab trees, for this calciphile species only occurs naturally in stands over limestone soil; elsewhere, baobab, clusters indicate earlier human settlements. The tree also has an important social role, belying the misnomer "palaver tree", which unfairly implies endless talk and even idleness. In fact, this tree plays a central and noble role in African life, serving as the community meeting place for consultation, discussion, education and also for the lighter side of rest and recreation.

Modern needs induced by urban expansion

Most towns in the Sahel have grown in a relatively unplanned way, with considerable improvisation in response to the influx of rural migrants seeking the mirage of a better life in the city. Town planners and urban populations have gradually come to be increasingly concerned by the following six aspects of trees and forests in an urban context.

Trees, towns and the use of urban ant peri-urban land. The rapid development of towns in developing countries often takes place in areas where land tenure has not been fully settled and where long term or, indeed, medium-term planning is not part of the equation. Conflicts concerning land use are therefore frequent. Problems of peri-urban land-use planning and regulation are particularly important in the Sahel countries.

Urban planners are now, however, trying to make up for lost time. Since the early 1900s, Dakar, a pioneer among Sahel cities, has had a series of master plans to govern the interface between urban and undeveloped land in an attempt to cope with heavy population pressure. Their implementation has been only partial at best, given the swift rise of shanty towns, unauthorized building and the race for the fait accompli, all of which have left little scope for the planning of green areas.

Neem trees line a peri-urban thoroughfare leading towards Dakar, Senegal

The other large towns in the Sahel enjoy relatively open spaces, despite the proximity of natural constraints or difficult settings (the banks of the Niger for Bamako and Niamey and the banks of the Chari for N'Djamena).

Urban sanitation development and plantations. Towns that spring up and grow rapidly usually face severe environmental sanitation problems as population increases far outstrip the development of needed infrastructures. Sahelian towns all have problems of swampy or temporarily flooded land, unstable slopes along coastlines or riverbanks and encroaching sands. All these problems have been encountered in Dakar (see Box): the main objective of the Hann Forest Park was to drain the Hann marshlands and lowlands and protect the aquifer; wells were sunk to provide drinking water to the town of Gorée. The Greater Dakar Urban Development Service (STAGD), the partial forerunner of the Parks and Gardens Service in Senegal, was responsible for stabilizing the coastline by planting trees.

Urban and peri-urban woodlands in Dakar: underutilized and endangered The city of Dakar was founded in 1857. Word has it that the small fishing village at the time owed its name to a little evergreen that is well known in the Sahel, the tamarind (Tamarindus indica). What is more certain is that the picturesque market in the heart of the capital, the "Sandaga", owes its name to another evergreen, the "sand" (Morus mesozygia) and that Portuguese sailors following the coastline noticed that the peninsula was particularly green and called it Cabo Verde. The different concerns of the various administrators of the island of Gorée? Dakar and its peninsula led to early land management, with the result that, today, the city has an excellent although not fully tapped - potential to develop an enviable system of parks, green areas and peri-urban woodlands. · Even at the beginning of the century, the Hann marshland, 7 km from the centre, was essentially developed as a water reservoir for Dakar and Gorée. Permanent wells were subsequently sunk and the 80 ha Hann woodland park was developed to serve as the headquarters of the General Forests Inspectorate of French West Africa. Yet, it also served as a recreational park and featured a small botanical garden and zoo for the benefit of Dakar's residents. In 1943, the colonial governor recognized the need to use brushwood and multispecies plantations to stabilize and embellish the coast to the east and west of the capital. The Dakar coastal headlands (Corniches) area was officially established in 1943 and abundantly planted, particularly in the east. Its western part, facing the Madeleine Islands National Park, is now under careful land-use management. · The Mbao reserve forest was established in 1940 over an area of 770 ha, although it was reduced to some 500 ha in 1970 to make way for Dakar's industrial zone. This prime peri-urban woodland is threatened by strong population pressure and particularly inadequate land-use planning. · The coastal areas. Reforestation was officially introduced over an area of more than 4000 ha along the sandy beach area of the capital in 1950. Its purpose was to fix the sand dunes and protect the coastal system (Malika, Retba, Cambérène). More than 2000 ha have been lost to construction (the Cambérène and Yoff areas) but the attractive filao plantations, which cover more than 1000 ha at a distance of less than 30 km from the city, are prime peri-urban woodlands. · A final belt with peri-urban woodland potential includes the forest of Deny-Youssouph (400 ha), the forest of Sebikhotane (520 ha) and the Dialao hills, which are under threat from quarrying activities. The urban triangle of Dakar-Mbour-Thiès. This triangle of towns less than 80 km from each other will become a megalopolis in 50 years, time. Land-use planning should be introduced now so that a large part of the existing reserved forests, covering more than 10000 ha (Pout, Thiès, Bandia, Nianing and Pointe Sarène), are maintained, reforested and equipped with facilities, and so that the natural stands (particularly of Acacia seyal) are rehabilitated. Tourist development along the Petite Côte and the immense needs foreseen for the future call for rigorous action now, especially along the lines of the extensive plantations, embellishment and road operations undertaken by the Société d'Aménagement de la Petite Côte (SAPCO). The potential for Dakar and the urban triangle is excellent if measures are taken soon - in ten years, time it will be too late.

Sahelian towns have to resist sand and dust encroachment every day. Vegetation buffers the impact of wind and sand, while the planting of stands, clusters and shelter-belts has become a common practice. The so-called green belt plantations in Nouakchott and the sand dune fixation plantations in the southern third of Senegal's Grande Côte are all essentially sand and dust protection devices. In the Niger, the peri-urban plantations of Niamey, of small towns such as Tahoua or of large villages such as Dogondoutchi serve to protect and develop the urban environment while also offering sources of fuelwood and timber.

Fuelwood supplies, pen-urban forests and plantations. While land clearing for rain-fed cultivation is what causes the greatest disturbance to plant formations in the rural Sahel, the need for fuelwood is the decisive factor that influences and governs the continued existence of natural forests, plantations and single trees in the peri-urban environment. The towns have gradually pushed back the forest to meet the greater need for fuelwood and charcoal which has accompanied galloping population growth. In Senegal, urban charcoal consumption alone is officially estimated to be 900000 m³ of wood but is probably more than 1500000 m³, which would correspond to 3000 to 5000 ha of savannah and steppe over a radius of 60 to 600 km from the town! Fuelwood production is therefore an obvious function that cannot be ignored in the design of urban and peri-urban forest systems in this subregion.

Systems to conserve natural forests for fuelwood supply or to plant trees to meet urban fuelwood needs have been the most common components of cooperation agencies and African government forestry and energy strategies during the last 20 years, particularly in arid and semi-arid areas (Leach and Mearns, 1988). Since 1950, forest development in Senegal's Bandia forest in the Dakar-Mbour-Thiès triangle, located less than 50 km from each of these towns, has centred on the production of fuelwood. In all other Senegalese forests that are too remote to be considered peri-urban and where some form of management has taken place, the focus has been on supplying fuelwood to urban areas, particularly Dakar. In Burkina Faso, the inventory and management of natural forests near Ouagadougou for fuelwood, started in 1981, offers a good example of forestry oriented towards both urban energy needs and the promotion of rural community participation.

Just as they would be in rural zones, the leaves of trees in urban areas of the Sahel, particularly parks, are often collected for food

The plantations or peri-urban green belts established around many towns in the Sahel before and particularly after 1970 focus primarily on fuelwood and other "environmental" objectives: eucalyptus plantations around Ouagadougou; plantations around Bamako (the Monts Mandingues forests for the mixed production of building poles, timber and fuelwood); peri-urban plantations in Niamey, based on eucalyptus as well as other species; and around N'Djamena, neem, rosewood (Dalbergia sisoo) and cailcedra (Khaya senegalensis) plantations as well as the reintroduction of protected Acacia seyal stands.

The socio-economic aspects of peri-urban fuelwood plantations are, however, complex and warrant close attention. The peri-urban land area is coveted for other purposes that produce quicker returns than fuelwood: fruit orchards and market gardens, building lots, land speculation and property development. Unless deliberate decisions are taken to defend forestry and unless realistic prices are set for wood (at least partially), it will be difficult to maintain or allocate peri-urban land to forest-oriented use.

Peri-urban forests for a sustained flow of locally produced and traditionally consumed products. The transfer of rural populations to urban areas does not necessarily mean a rapid change in consumption patterns. The consumption of popular forest foods in the large towns (baobab leaf, tamarind, processed Parkia seeds, etc.) is virtually identical to the products on sale at a rural market. Palm trees are tapped for palm wine (Dakar, Thiès). In the forest of Mbao, 15 km from Dakar in Senegal, local species whose leaves, bark or roots have medicinal use are intensively exploited and could become endangered species (Anthostema senegalensis, the Tinospora bakis creeper and the rutaceous Fagara xanthoxyloides, to name but a few). The uses of natural formations in peri-urban forest systems should influence management and development decisions. Thus, participatory management of the Guesselbodi forest, close to Niamey in the Niger, included both the collection of stubble for urban rearing of small livestock, and the picking of wild fruit. The management of the Monts Mandingues forest could benefit considerably from a greater emphasis on everyday consumer products such as the fruit of the Saba senegalensis (a very hardy species abundant in cultivated and fallow areas) for which there is a high and certainly unsatisfied demand in Dakar and Bamako.

These observations confirm that the peri-urban forests in the Sahel should be used for multiple purposes.

Species used in Sahelian urban forestry

Species	Use	Origin	Degree of use
Acacia holosericea	Fences, street trees	i	*
Acacia sp.	Ornamental	L	**
Araucaria sp.	Ornamental	i	**
Azadirachta indica	Shade, street trees	i	****
Bauhinia thonningii	Ornamental	i	*
Bauhinia sp.	Hedges, ornamental	L
Bombax costatum	Ornamental	L	*O
Cassia siamea	Street trees, shade	i	**­
Casuarina equisetifolia	Shade, street trees	i	**®
Ceiba pentandra	Ornamental	s	**¯
Cordia sp.	Ornamental	i	**­
Combretum paniculatum	Ornamental	L	*O
Crescentia cujete	Ornamental	i	*O
Cycas sp.	Ornamental	i	*
Dalbergia sissoo	Ornamental	i	*O
Delonix regia	Ornamental	i	**¯ O
Eucalyptus spp.	Ornamental, other	i	***­
Ficus thonningii	Shade, ornamental	L	**¯ O
Gaiacum officinale	Ornamental, fences	i	**­ O
Gmelina arborea	Ornamental, shade	i	**­
Grevillea robusta	Ornamental	i	*
Hura crepitans	Ornamental, street trees	i	**O
Khaya senegalensis	Shade, ornamental street trees	L	***¯ O
Leucaena sp.	Ornamental, fences	i	**­
Lonchocarpus sericeus	Ornamental, fences	i	**
Melia azedarach	Ornamental	i	*O
Moringa pterigosperma	Ornamental, food	i	**O
Peltophorum sp.	Shade	i	*¯
Pithecellobium dulce	Hedges, shade	i	*O
Prosopis (chilensis + juliflora)	Hedges, shade (in the north)	i	***­
Sapindus saponaria	Ornamental, religious	i	**¯ O
Spondias purpurea	Ornamental, fences, fruit, shade	i	*¯ O
Tamarix sp.	Shade, ornamental	L + i	*­ O
Tecoma pentaphylla	Shade, ornamental, street trees	i	**¯ O
Tecoma stans	Ornamental, gardens	i	*
Terminalia catappa	Ornamental, shade	i	**
Terminalia mantaly	Ornamental	i	***­
Thespesia populnea	Ornamental	i	*¯

i = introduced (exotic);
L = local (indigenous);
s = subspontaneous;
* = little used;
** = used moderately;
*** = heavily used;
**** = used predominantly
® ­ ¯ = stable, increasing or decreasing trend;
0 = underutilized potential

Note: The table shows the extreme weakness of local or indigenous species used in plantations or for ornamental purposes in three Sahelian cities. There are, however, numerous species with important potential for aesthetic improvement of cities: Combretum spp., the many species that Dour in the cool and dry season, for example the genera Stereospermum knuthianum, Lonchocarpus, Bombax; the indigenous Anacardiaceae, in particular the Lannea numerous acacias, and many other species than can be rooted from cuttings. A programme of horticultural research could contribute to the fuller exploitation of this tragically underutilized potential.