Forests and planted trees provide sustenance to many millions of people in Africa, particularly the vulnerable, women and children. Balancing utilisation of forest resources and growth of forests and trees forms the basis of sustainable forest management (SFM). Africa’s natural and planted forests are not sustainably supplying wood and other products to meet the needs of the growing population as well as the demand of national, regional and international markets. Serious shortages of wood are forecast in many countries for the near future and this has negative socio-economic implications. The African Forest Forum (AFF) recognised the need to improve SFM in Africa through planting trees using genetically improved planting stock for establishment of industrial plantations, community tree woodlots and agro-forests. This report is based on situational analyses of tree breeding and tree germplasm supply conducted in West and Central Africa (Avana-Tientcheu, 2016), Eastern Africa (Msanga, 2016) and Southern Africa (Marunda, 2016).
To understand trends in the choice of species and estimate seed demand, the studies looked at forest statistics in selected African countries and reviewed the history of tree planting (introduction of species and provenances), afforestation, reforestation statistics and conservation needs. Plantation development has been generally successful in countries where the private sector has been encouraged and supported to invest in tree planting (e.g. South Africa, Tanzania and Congo), research (Congo, Ghana, South Africa, Tanzania and Zimbabwe) and tree germplasm development (Burkina Faso). Community tree planting for agroforestry, whilst still in the nascent stages of development, has been encouraged and supported by international donors. Distribution of seed is mainly through informal farmer networks supported by local and international organisations, national tree seed centres (e.g. Burkina Faso) and the private sector (e.g. in South Africa). The users of tree germplasm in African countries have become diverse – from large plantation corporations, community-based organisations and city councils, to small-scale tree growers, including farmers groups and individual farmers including women keen to plant indigenous fruit trees to improve their livelihoods. This diversity brings with it challenges and opportunities. Challenges may include how to supply a variety of high quality tree seed from a range of species whilst the diversity offers opportunities for the rural communities to be involved in the supply chain of tree germplasm.
The studies showed that Africa, like most parts of the world, has imported, tested, shared, exchanged, sold and improved genetic resources for tree species. Use of genetically improved planting stock was reported in all countries in Africa although the levels of use vary from country to country, with countries such as South Africa having the most sophisticated tree germplasm development and deployment systems. Some countries, e.g. South Africa and Zimbabwe, acknowledged the presence of species and provenance trials which revealed the best performing species and provenances, seed sources and provided the material for tree improvement and for subsequent deployment to operational plantings. Other countries, especially in West and Central Africa (except Ghana), reported that most provenance trials were abandoned and illegally exploited and most data and information has been lost.
A new wave of establishment of commercial plantations is sweeping through many parts of Africa, for example in Congo (Eucalyptus Fibres du Congo), Ghana (Africa Plantations for Sustainable Development, Siricec, Miro Forestry), Mozambique (New Forests Green Resources, Florestas Do Planalto, Chikweti Forests, Florestas de Niassa), Rwanda (New Forests), South Africa (International Finance Corporation, Hans Merensky), South Sudan (Maris Capita), Tanzania (Green Resources, New Forests, Kilombero Valley Teak Company), Zambia (Green Forest Development) and Uganda (Sawlog Production Grant Scheme). This new wave of plantation development has seen an increase in the demand of tree germplasm and new species for planting in marginal areas that are available for afforestation.
In 2016, the Forests for the Future – New Forests for Africa initiative was launched in Ghana with the aim to stimulate and drive large scale reforestation in Africa. The set target is to plant 100 million hectares of new forests. The Great Green Wall Initiative was launched in 2011 and involves 12 countries of which 8 are from West Africa. The goal is to plant trees as a means to try to stop, or even to reverse, the desertification process, which is the main ecological problem of many countries with arid climates (e.g., Niger, Chad, Mali, Nigeria, Burkina Faso, Mauritania and Senegal). The need and call to plant more trees (e.g., Billion Trees Campaign and Green Belt Movement) will increase the demand for seed and new species, and national tree seed centres will need to be prepared for the increased seed demand and identify priority tree species.
The reviews of tree breeding and tree germplasm supply and demand in Africa showed a decreasing trend in research and development investments and widening gaps in the supply of good quality germplasm. Given the forecasted increase in tree planting and the recorded threats of pest and diseases to forest genetic resources in Africa (Bosu, 2016; Gichora, 2016; Kojwang, 2016;), tree planting programmes in Africa might not reach the optimum productivity levels if germplasm supply and pest and disease threats are not addressed. Forestry development in Africa will have to address these issues as part of a wider programme to achieve SFM.
It is clear that most African countries recognise that SFM is achieved by combining strategies that conserve and encourage regeneration of native tree (e.g. Ngitili in Tanzania; Zai in Burkina Faso; landscape restoration in Maradi and Zinder (Niger), coppice management in the miombo woodlands of Southern Africa) and the promotion of tree planting at large plantation scales and at the farmer level. The choice of species for commercial plantations has been decided based on decades of research on species trials and collaborative research for agroforestry species. For newer species for agroforestry, research is still fairly new and a number of candidate species are still being tested and promoted.
The commonly planted species in Africa are Eucalyptus, Pinus, Acacia, Hevea species Tectona grandis and Gmelina arborea for the primary supply of industrial wood, rubber, gums and fuelwood. The first two genera have formed the backbone for commercial tree planting and have undergone several cycles of selections and in some cases mating to create new clones or varieties. The genera are attractive because of the shorter economic and reproductive rotations that are possible. Recently, agroforestry species for intercropping, alley cropping, fodder provision and indigenous fruit trees have been tested for growth and productivity in many African countries. Indigenous tropical hardwoods such as Khaya senegalensis, Khaya anthotheca and Milicia excelsa have been domesticated as plantation species in tropical countries. Acacia senegal and Acacia seyal have been planted in plantations for gum Arabic production (hashab and talha from the two species respectively). Faidherbia albida is commonly planted throughout the continent for soil amelioration, provision of fodder for livestock and firewood.
A number of indigenous commercial hardwoods are harvested from natural forests in all the regions but more so in West Africa. Priced hardwoods such as Milicia excelsa, Entandrophragma spp., Triplochiton scleroxylon, Terminalia spp., Nauclea diderrichii, Khaya spp., Pericopsis elata and many others are harvested by concessionaires. Although most of the countries developed sound forest policies oriented toward sustainable forest management, there are low levels of incentives to conserve or apply sound silvicultural practices to ensure regeneration of most species. Germplasm of good phenotypes is therefore lost during harvesting, as seed is not collected for replanting. Physiological characteristics of seeds for most tropical hardwood species are either recalcitrant or unknown (i.e., do not store for long periods under low temperature and moisture conditions), thus making it difficult to store the seed for future use.
The review of tree germplasm production in Africa showed that Africa’s forest sectors, both commercial and community forestry, need quality seeds, but the continent’s capacity to supply good tree planting stock varies from good to poor depending on the country. Countries often lack the institutional capacity to support the growth of tree seed markets (an issue that cuts across boundaries), tree breeding research, seed production, seed storage and testing, and regulation. Expertise in tree breeding, tree germplasm management and investment could help build the capacity to produce good quality tree seeds and improve on other aspects of the tree seed sector, including management, logistics, deployment and the integration of new species and technologies.
Since many tree species used in plantations or agroforestry were found to be the same across the continent, indicating a wider ecological and economic range than individual countries, it is prudent to have regional research programmes on tree breeding and improvement, germplasm management, and share information on silvicultural aspects, environmental benefits, impacts on soils and biodiversity, pest/disease prevention, wood utilisation and economics.