During the last two decades environmentalists, foresters and political leaders at all levels raised concerns about the loss and growing decline in the state of tropical forests, particularly in sub-Saharan Africa (SSA). Responses during the current decade focused on mobilizing strong commitment to progress towards sustainable forest management in accordance with the "Forest Principles" agreed at the United Nations Conference on Environmental and Development (UNCED) in 1992. The concept of sustainable forest management, which balances environmental, socio-cultural and economic needs, has stimulated changes in forest policies, legislation and forest management practices in many countries. Forests managed in this way will continue to produce multiple products including wood, and non-wood forest products while supporting habitats for wild life and landscape for ecotourism, peasant security through provision of fuelwood, food and various goods and services, and environmental stability.
Although planned conversion of forests to alternative land use needs is logical, the present rate of forest depletion and degradation in SSA is alarming. Annual deforestation of SSA forests was 0.7 per cent for the period 1981-1990, reflecting a significant increase in the 1980s compared to the previous decade (FAO 1995). The primary agents of forest degradation and depletion are unsustainable logging, excessive woodfuel harvesting and irrational conversion of forests to cropland, ranching and settlements. The latter conversion without consideration of the capability and limitations of the land and this has led to a decline in food production in many countries. Many of these activities are driven by population pressure, escalating poverty, perverse policies and bad governance.
This happened despite the adoption of guidelines for sustainable forest development undertaken recently under the tropical forest action plan (TFAP). TFAP incorporated forest and legislative reforms, institutional re-structuring, including decentralization and forging of partnerships with communities and the private sector.
During pre-colonial times African communities managed their forests according to traditional rules and guidelines, underpinned by local beliefs and norms. These rules assured sustainable resource management. Forests met the basic needs of the society of the day, and inter-generation equity. The traditional systems worked well due to unquestionable authority of the elders, uncontested respect for taboos and the low population of communities that occupied small land areas.
Scientific forest management dates from the dawn of colonial administration, from the end of the 19th and the beginning of the 20th centuries. The main goals of forest management have been to maintain and safeguard adequate forests to ensure sufficient supply of timber (for local construction, saw-milling and export), fuel wood, poles and other products, to optimise economic and environmental benefits and to promote an understanding of the forests and trees. Early management roles included forest reservation and demarcation to separate them from private and public land to ensure their security. Many countries introduced management plans to facilitate sustained logging from forest reserves for a sustainable timber supply, following specified minimum diameter limits. Initially the forests were managed on sustained yield basis for timber. During exploitation, forest yield was regulated by polycylic method of working with 30-90 years intervals between felling. This method could not yield enough volume of exploitable timber sizes and the monocyclic method of yield regulation was adopted involving rapid development of regeneration through drastic opening of the forest canopy. Consequently the silvicultural system known as "tropical shelter-wood" was adopted to regenerate the natural forests, in many countries.
Different interventions regarding silvicultural treatments and tending were practiced to increase the productivity of the forest and economic benefits. Various underplanting techniques of natural forests were tried including direct sowing of indigenous tree species, enrichment planting using fast growing species, elimination of undesirable species using chemicals and the development of compensatory industrial plantation programmes.
A technique of arboricidal (chemical) tending of mixed forests was introduced by early 1950s and extensively used for selective weeding or stand requirement. Charcoal burning and pit sawing were also introduced in the forests to enhance revenue generation.
At the same time conservation of flora and fauna was supported through maintaining a network of nature reserves within the forest estate to provide benchmarks on the development of pristine forests. Permanent sample plots (PSPs) were also established in representative sites in the forest reserves to provide a basis for assessing growth, mortality, and regeneration.
Substantive forest policies and legislation were developed progressively, particularly after the sixth commonwealth forestry conference held in Ottawa, Canada, in 1962. The forest policy statements developed by Anglophone SSA countries, which were later endorsed by independent states in the 50s and 60s, have a common feature, not surprisingly due to having a common colonial heritage. The policies generally provided for: (a) maintenance and, where possible, increase of the area of forests and tree cover, (b) conservation of natural habitats and their complement of wildlife and biological resources, (c) support of sustainable agriculture and conservation of soil and water resources, (d) poverty alleviation and promotion of rural development, (e) production of wood and non-wood resources, and (f) maintaining a viable and efficient forest industry.
But in many countries forest development remained limited to boundary patrols, fire management, and logging. Even where forest management plans were developed these were rarely followed. The war-time and post war period saw increased logging within and outside the forest estate.
In some countries, particularly in East and southern Africa, colonial settlers encroached on forests and occupied most of the fertile and productive tracts of land. At the same time, local people were systematically denied access to the forests and associated resources, and pushed to marginal regions of the countries (low rainfall and poor soils). These areas were easily eroded and degraded by overgrazing and over-utilization. As their numbers increased and their land became environmentally degraded and unable to yield adequate food, they were only kept away from the forests by colonial armed guards. It is this development that set a permanent state of war between communities and the government's forest guards in enforcing sustainable forest management plans.
In virtually all the countries, forests were soon seen as government resources from which communities were alienated through policy fences enforced by a paramilitary cadre of forest guards. The main management agenda was to maximize revenue collection for local and central governments, generation of employment and promotion of wood-based industries.
Many SSA countries became independent with substantial public forests of mature commercial timber. During the post-independence period, countries promoted rapid forest depletion by conceding much of their economic value to concessionaires that contract with the government to harvest timber on public lands, to generate revenue. Heavy logging has particularly occurred in countries under civil strife or military rule. The period between the 60s and 80s witnessed widespread erosion of forests through intensified and non-sustainable logging and conversion of vast areas of secondary forests to alternative landuse systems and industrial plantations through a taungya system of crop cultivation in the forest estate.
This paper reviews the benefits of secondary forests to the SSA countries, and examines the ecological factors influencing secondary forest management, the state of knowledge and management experiences, and constraints to sustainable management. It proposes appropriate research priorities, and provides recommendations for action. In most cases information is lacking on the use and management of secondary forest, and the text refers to the management of primary forest. The idea is to take note of the problems in order to adapt and improve the management of secondary forests.