Secondary forests are forests regenerating largely through natural processes after significant human or natural disturbance of the original forest vegetation at a single point in time or over an extended period, and displaying a major difference in forest structure and/or canopy species composition from the nearby primary forests on similar sites. Large areas of natural forests in the tropics and sub-tropics, being heavily degraded, cannot provide forest functions sufficiently and their production potential remains largely untapped. Secondary forests comprise a large and growing proportion of the forest cover in these regions and are very important at the local, national and regional levels for a wide range of products and environmental services (CIFOR, 2000). The status quo is attributed to continuous utilization pressure combined with deficiencies in the recognition and implementation of land rights and a shortage of skills required for the management of the forests. The degradation of forest ecosystems will continue and is envisaged to accelerate the creation of secondary forests in the foreseeable future unless counter measures are implemented.
The rehabilitation process will require different forms of interventions, depending on the degree of degradation. Degraded forests are characterised by a decrease in canopy cover and density after selective exploitation of valuable tree species. Once the utilization pressure decreases they tend to recover. Degraded land is often associated with decline in soil conditions. Such land can be rehabilitated by undertaking afforestation which requires substantial inputs, which are often lacking. Degraded and secondary forests can quite often be rehabilitated with specific small-scale interventions. However, appropriate skills and ecological knowledge are essential prerequisites.
Both situations above pose serious silvicultural challenges that need to be addressed through exchange of information and experiences, research and conducive policy environments. It is envisaged that in future, Africa's tropical forest resources (primary and secondary forests) could be managed in the following three categories:
The main forest management task will be to transform degraded and secondary forests into multifunctional and semi-natural production forests.
Concern is rising about the adverse consequences of tropical deforestation. The loss of primary forest cover results in creation of secondary forests and influences the climate and contributes a reduction of biodiversity. Reduced timber supplies, siltation, and flooding and soil degradation affect economic activities and threaten the livelihoods and cultural integrity of forest dependent people (Angelsen and Kaimowitz, 1999).
Tropical Africa has 18 per cent of the world's closed tropical forests, but contains 66 per cent of the world's open forest. The open forest is characteristic of the drier edges of the Congo basin and East Africa. The proportion of Africa covered by secondary forests is not known. But clearing the forest by traditional and manual means has reduced the area of primary forests and increased the area of secondary forests. These forests are very useful to local communities but governments, foresters and conservationists often ignore them (Pye-Smith, 2002a). Secondary forests are important for a variety of reasons. They provide local people with many of the same goods and services as primary forests. In addition, they may contain a large number of species depending on some degree of disturbance or destruction of the original primary forest. However, reality shows that the number of species in a secondary forest is initially low.
Secondary forests are often important hunting grounds for local people and they supply them with fuel wood, fruits, nut, fibres, timber, poles and other foodstuffs. This makes them especially important for the rural poor.
Secondary forests often provide important wildlife habitat, although they may differ significantly from primary forests in terms of vegetation structure and species composition. Some species are seldom found in secondary forests e.g. Cynometra alexandrii (ironwood) in the Budongo forest in Uganda. Some animals show a distinct preference for primary forests, but certain browsing mammals e.g. duiker and some birds, may actually prefer secondary forests.
If they are well managed, secondary forests can provide timber on a sustainable basis. They also deliver many of the same environmental services as primary forests. For example, they may be important in terms of watershed and soil protection, and frequently they fix atmospheric carbon faster than mature forests, and thus could play a more significant role in countering global warming. As such, secondary forests matter but their survival and well-being are threatened by illegal logging, road building, urban development and other activities. However, attitudes towards secondary forests are beginning to change gradually. Many countries in Africa with little remnant forest are increasingly recognising their significance both for environmental and local livelihood purposes. In many African countries large rural populations depend on secondary forests for fuel wood, livestock grazing, medicinal plants and a host of other products. In contrast, countries that still have significant areas of primary forest have tended to ignore their secondary forests.
There is a need to establish exactly where secondary forests are, what they are threatened by, and who is using them so that countries can work out how best they should be managed for future generations. It is also time for conservation agencies such as WWF, IUCN and Conservation International to recognise the important role which secondary forests play in conserving biodiversity. However, this should not in any way diminish the need to preserve and protect primary forests.