by
M. Sacandé and H.W. Pritchard21
Deforestation affects the daily life of millions of people. In sub-saharan Africa, forests are still disappearing at a rate of nearly one percent a year (FAO, 2003), despite the many reforestation and conservation programmes. Alarmingly, it is estimated that c. 2000 tropical tree species in this region are considered to fall into the categories of being ‘near-threatened’ to ‘critically endangered,’ as determined by IUCN (2002) and UNEP-WCMC (2001) (see Figure 1).
From a biodiversity perspective, this situation is partly exacerbated by the (over) use of only a handful of genera and families in most cultivated forests in sub-saharan Africa; for example, the Fabaceae (Leguminosae), Meliaceae, Myrtaceae and Verbenaceae (Schmidt, 2000; FAO, 2001). The attraction of these species groups has been fast growth and a relatively rapid economic return. But many of these species are exotic and the well-adapted natural resources have often been neglected. As a consequence, many species of local socio-economic importance are still under-utilized.
Clearly, efforts are needed to counteract species vulnerability as a result of the decline of their forest ecosystems. Raising trees and preserving their seeds are means of supporting reforestation, combating desertification, safeguarding the environment and conserving biodiversity. However, this is an enormous challenge that requires the planting of large numbers of adapted species. This also implies a need for careful selection of species for use and a great demand for quality seeds.
Figure 1. Estimated numbers of threatened tree species in sub-Saharan Africa by category of threat. The data were obtained from country reports from various sources (see IUCN, 2002, http://www.unep-wcmc.org/trees/Background/africa.htm)
Recognizing this short-coming, representatives of 18 countries, mostly from Western Africa (Table 1), gathered in Dakar in April 1997 to discuss the management and sustainability of tree seed programmes in the region (PRONASEF, 1997). The meeting proposed a regional approach for the sustainable management of forest genetic resources. The first technical workshop was held in Ouagadougou, Burkina Faso in 1998 and focused on the setting up of a regional collaborative programme on forest genetic resources for selected species (Ouedraogo and Boffa, 1999). Initially, the countries listed 302 highly important species with multiple uses. Ultimately, a species was selected if it was mentioned by at least 10 countries (Eyog Matig and Ouedraogo, 1999), to be included in the sub-Saharan Africa forest genetic resources (SAFORGEN) list for priority actions.
A second regional group, of mainly the South African Development Community countries, supported by FAO, IPGRI, ICRAF and Danida Forest Seed Centre, met in Arusha, Tanzania in June 2000 for a sub-regional workshop on forest and tree genetic resources. Priority tree species and common issues amenable to regional co-operation on conservation activities were identified by nine countries (Table 1). Ten important native species to this region were acknowledged as a top priority for consideration by at least two of these countries (Sigaud and Luhanga, 2000).
Table 1. Countries that participated in SAFORGEN technical workshops in Burkina Faso and in Tanzania
Countries at the Ouagadougou workshop (1998) |
Countries at the Arusha workshop (2000) |
Benin, Burkina Faso, Cameroon, Cape Verde, Central African Republic, Chad, Congo, Côte d’Ivoire, Gabon, Guinea, Kenya, Madagascar, Mali, Mauritania, Niger, Senegal, Sudan, Togo |
Botswana, Malawi, Mauritius, Mozambique, Namibia, Swaziland, Tanzania, Zambia, Zimbabwe |
In consolidating these two regional programme lists, 59 species were identified for urgent attention for in and ex-situ conservation effort. In addition, three genera (Combretum, Entandrophragma and Terminalia) were also cited for attention (Ouédraogo and Boffa, 1999; Sigaud and Luhanga, 2000; Table 2). The species fall into four key groups, based on socio-economic and ecological criteria: (1) producing edible fruits, (2) forage species, (3) species mostly used as timber and for amenities, and (4) species used for crafts and other non-wood products.
In parallel to these discussions and developments, sub-Saharan African countries - in collaboration with various international and national agencies - got together (see IUFRO workshops in Kenya, 1992; Madagascar, 1994; Senegal, 1997; Burkina Faso, 1992; 2001) to emphasize the potential role that seeds could play in the preservation and regeneration of forest genetic resources.
More effective use of the seeds of these selected species is highly desirable, but is still hindered by a shortage of knowledge of their seed biology (development, storage and germination). During the last two decades, numerous symposia and workshops have been held on tropical forest seeds, and several proceedings of the International Union for Forest Resources Organizations (IUFRO) have been produced with special reference to tree seed problems (see Kamra and Ayling, 1987; Turnbull, 1990; Some and De Kam, 1993; Olesen, 1996; Marzalina et al., 1999). Concurrently, technical books on tropical forest seeds have been produced (FAO, 1985; Albrecht, 1993; Tompsett and Kemp, 1996; IPGRI/DFSC project, 1996; Poulsen et al., 1998; Schmidt, 2000). Nonetheless, there is still a relative dearth of information on tropical tree seeds, in general. For example, in a compendium of information on the seed storage behavior of c. 7 000 species published recently, only 0.2 percent of those listed are tropical tree seeds (Hong et al., 1998). Although the seed biology of a small number of species (Khaya anthotheca, Khaya senegalensis, Lannea microcarpa, Pentadesma butyracea, Sclerocarya birrea, Trichilia emetica, Vitellaria paradoxa, Warburgia salutaris and Ximenia americana) on the SAFORGEN list has been investigated since 1996, as part of a project on “the handling and storage of recalcitrant and intermediate tropical forest tree seeds” [IPGRI/Danida Forest Seed Centre (DFSC), see Ouedraogo et al., 1996, 1999], the majority remain under-researched.
Because most of the species have high levels of diversity and their areas of distribution cross national boundaries, co-operative actions have been agreed to avoid redundant effort and to promote complementarity. Indeed, national tree seed programmes (e.g. in Burkina Faso, Ethiopia, Kenya, Madagascar, Niger, Senegal, Sudan, Tanzania, Togo and Zimbabwe), which have been established in African countries in the last 20 years, attempt to do this (Eyog Matig and Ouedraogo, 1999). However, it is still the case that the institutes require technical and other support. For example, strengthening of research capacity in such institutes is a key to adequate, longer-term availability and provision of quality seeds. In addition, there is a need to exchange information more efficiently between partners in tree conservation and sustainable use programmes (Eyog Matig and Ouedraogo, 1999; Sigaud and Luhanga, 2000; Proceedings Ouagadougou Workshop, 2002, in press and pers. comm.).
Table 2. SAFORGEN priority list of forest tree species identified by > 10 countries as highest priority for management and conservation actions in 27 sub-Saharan countries. Species produce edible fruits (fruit) and African timber (timber). Some are important forage species (forage), and amenity and fuel-wood species (non-wood products). Species names authorities come from TROPICOS, from the Missouri Botanical Garden: http://www.mobot.org or IPNI (The International Plant Names Index): http://www.ipni.org/index.html .
Species |
Main uses |
Species |
Main uses |
Acacia nilotica (L.) Willd. ex Delile |
Non-wood |
Grewia bicolor Juss. |
Forage |
Acacia raddiana Savi. |
Forage |
Irvingia gabonensis (Aubr.) Baill. |
Fruit; Non-wood |
Acacia senegal (L.) Willd. |
Forage; Non-wood |
Isoberlinia doka Craib & Stapf |
Timber |
Adansonia digitata L. |
Fruit; Forage; Timber; Non-wood |
Khaya anthotheca (Welw.) C. DC. |
Timber |
Afzelia africana Sm. |
Forage; Timber |
Khaya ivorensis A. Chevalier |
Timber |
Afzelia quanzensis Welw. |
Timber; Non-wood; |
Khaya senegalensis (Desr.) A. Juss. |
Forage; Timber |
Aningeria altissima (A. Chev.) Aubrév. & Pellegr. |
Timber |
Lannea microcarpa Engl. & Kr. |
Fruit |
Anogeissus leiocarpus (DC.) G. & Perr. |
Timber |
Lophira alata Banks ex C. F. Gaertn. |
Timber |
Aucoumea klaineana Pierre |
Timber |
Maerua crassifolia Forsk. |
Forage |
Baikiaea plurijuga Harms |
Fruit; Forage; Timber; |
Milicia excelsa (Welw.) C.C. Berg |
Timber |
Balanites aegyptiaca (L.) Del. |
Fruit; Forage; |
Nauclea latifolia Blanco |
Non-wood |
Bauhinia rufescens Lam. |
Forage; |
Parinari curatellifolia Planch. |
Non-wood |
Borassus aethiopum Mart. |
Fruit; Non-wood |
Parkia biglobosa (Jacq.) R. Br. Ex G. Don |
Fruit |
Borassus flabellifer L. |
Fruit |
Pausinystalia johimbe (K. Schum.) Pierre ex Beille |
Non-wood |
Carapa procera DC. |
Fruit |
Pentadesma butyracea Sabine |
Fruit |
Cola nitida (Vent.) Sch. & Endl. |
Fruit |
Prosopis africana (G. & Perr.) Taub. |
Forage |
Colophospermum mopane (J. Kirk ex Benth.) J. Léonard |
Timber; Non-wood |
Pterocarpus angolensis DC. |
Forage; Timber |
Combretum aculeatum Vent. |
Forage; Timber |
Pterocarpus erinaceus Poir. |
Forage; Timber |
Combretum sp. |
Timber |
Pterocarpus lucens Lepr. |
Forage |
Commiphora africana (A. Rich.) Engl. |
Forage |
Ricinodendron heudelotii (Baill.) Pierre. |
Fruit; Non-wood |
Dacryodes edulis (G. Don) H. J. Lam. |
Fruit |
Sclerocarya birrea (A. Rich.) Hochst. |
Fruit; Forage; Non-wood |
Dalbergia melanoxylon Guill. & Perr. |
Fruit; Timber |
Spondias mombin L. |
Fruit |
Daniellia oliveri (R.) Hutch. & Dalz. |
Timber |
Sterculia setigera Del. |
Non-wood |
Detarium microcarpum G. & Perr. |
Fruit; Timber |
Tamarindus indica L. |
Fruit |
Diospyros mespiliformis Hochst. ex A. DC. |
Fruit; Timber |
Terminalia sp. |
Timber |
Entandrophragma sp. |
Timber |
Trichilia emetica Vahl. |
Non-wood |
Faidherbia albida (Del.) A. Chev. |
Forage; Non-wood |
Triplochiton scleroxylon K. Schum. |
Timber |
Garcinia afzelii Engl. |
Non-wood |
Vitellaria paradoxa Gaertn. |
Fruit; Non-wood |
Garcinia epunctata Stapf |
Non-wood |
Warburgia salutaris (Bertol. F.) Chiov. |
Fruit; Non-wood |
Garcinia kola Heckel. |
Non-wood |
Ximenia americana L. |
Fruit |
Gnetum africanum Welw. |
Non-wood |
Zizyphus mauritiana Lam. |
Fruit; Non-wood |
Action to specifically address some of the issues raised above is underway through a Darwin Initiative project (2003-2006) supported by the Department of Environment, Food and Rural Affairs (DEFRA, United Kingdom Government). The project aims to increase seed biology knowledge for all 59 species (from 22 families), and some additional species in three genera (Combretum, Entandraphragma and Terminalia), over a three year period. This will be achieved in collaboration with 40 scientists from institutes from about 15 African nations. Already two regional research workshops have been held in Burkina Faso (August 2003) and Ethiopia (September 2003) for scientists from nine (Benin, Burkina Faso, Cape Verde, Côte d’Ivoire, Ghana, Mali, Niger, Nigeria and Togo) and six (Botswana, Ethiopia, Kenya, Malawi, Tanzania and Uganda) countries, respectively. These workshops followed a United Kingdom planning meeting in the United Kingdom in July 2003 which was attended by 13 countries. Partners will establish a network web presence, will publish co-authored research papers and cascade their experience to others in their institutes. The group will present their findings at a final research workshop in Kenya early in 2006. The project will be supported at a technical level by both Millennium Seed Bank Project and IPGRI staff.
Thanks to Lambert Ouedraogo (CNSF, Burkina Faso), Ehsan Dulloo and Jan Engels (IPGRI, Rome) and colleagues in the Seed Conservation Department (Royal Botanic Gardens, Kew, Wakehurst Place) for helpful discussions on this work. Funding from the Darwin Initiative (DEFRA, UK) is gratefully acknowledged. HWP and MS also acknowledge financial support from the Millennium Commission, the Wellcome Trust and Orange plc. The Royal Botanic Gardens, Kew receives grant-aided support from DEFRA, United Kingdom.
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21 Seed Conservation Department, Royal Botanic Gardens, Kew, Wellcome Trust Millennium Building, Wakehurst Place, Ardingly, West Sussex RH17 6TN, UK
