Priority Indigenous Fruit Trees in the African Rainforest Zone: Insights from Sierra Leone
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Genet Resour Crop Evol (2017) 64:745–760 DOI 10.1007/s10722-016-0397-9 RESEARCH ARTICLE Priority indigenous fruit trees in the African rainforest zone: insights from Sierra Leone Amadu Jusu . Aida Cuni-Sanchez Received: 27 October 2015 / Accepted: 21 March 2016 / Published online: 20 April 2016 Ó Springer Science+Business Media Dordrecht 2016 Abstract There is an increasing interest in indige- potential for agroforestry in the country. The findings nous fruit trees (IFTs) and their potential role for highlighted that previous IFTs prioritization in Camer- agroforestry, food security and poverty alleviation. oun and Nigeria were not representative of the whole Despite the growing numbers of studies on IFTs in African rainforest zone. A new approach was suc- Africa, little research has focused on the rainforest cessfully used to identify the IFTs with greatest zone outside Cameroun and Nigeria. This study potential for agroforestry in Sierra Leone. This simple investigated if the important IFTs of Sierra Leone cost-effective approach, which straightforwardly are among those previously identified as ‘priority’ identifies opportunities and challenges for each species for this zone and, as they are not, a new species, could be used elsewhere in the tropics to approach combining focus-group data, field observa- establish a baseline for future domestication programs. tions, a market survey and a ranking exercise was used to determine which IFTs have highest potential for Keywords Agroforestry Á Farmers’ preferences Á agroforestry in a given area. Results indicated that the Fruit trees Á Rainforest zone Á West Africa most important IFTs in Sierra Leone as established by local farmers are Parinari excelsa Sabine, Cola lateritia K. Schum., Pentaclethra macrophylla Benth., Heritiera utilis (Sprague) Sprague and Bussea occi- Introduction dentalis Hutch. However, following the ranking exercise, the species H. utilis, Garcinia kola Heckel In rural communities in Africa, food security can be and Beilschmiedia mannii (Meisn.) Benth. et Hook. f. improved and poverty alleviated by diversifying the ex B. D. Jacks., highly appreciated by locals, already farming systems through the introduction of indige- managed by some farmers and reported ‘difficult to nous fruit trees (Ofori et al. 2014). Most indigenous find in the wild’, were found to have the highest fruit trees (IFTs), considered neglected or underuti- lized, are fruit bearing trees that are locally available, not highly researched and which are generally ignored A. Jusu Á A. Cuni-Sanchez (&) by the formal commercial sector. IFTs provide an Gola Rainforest National Park, Kenema, Sierra Leone alternative source of nutrition, especially in times of e-mail: [email protected] famine, can be an important source of cash income and often, are also used as medicine (Akinnifesi et al. A. Cuni-Sanchez Center for Macroecology, Evolution and Climate, 2008). The value to rural communities of non-timber University of Copenhagen, Copenhagen, Denmark products harvested from wild trees in the tropics, 123 746 Genet Resour Crop Evol (2017) 64:745–760 including IFTs, has recently been reviewed and et al. 2014), Akinnifesi et al. (2008) reports that the highlighted by Dawson et al. (2014). IFTs improve priority species for the African rainforest zone are well site conditions by nitrogen fixing, by avoiding soil the four above-mentioned species together with Vitex erosion or by increasing soil moisture. Despite these doniana Sweet and Syzygium guineense (Willd.) DC. ecological benefits, most IFTs are not cultivated and Considering higher levels of biodiversity in the therefore are mainly collected from the wild. There are rainforest zone compared with the drylands, this is however some exceptions as some IFTs have been surprising. The fact that most research on IFT and their subject to domestication. For instance, bush mango domestication in the rainforest zone has been carried (Irvingia gabonensis (Aubry-Lecomte ex O’Rorke) out in Cameroon and Nigeria (see Tchoundjeu et al. Baill.), which has been subject to participatory 2013) might explain this situation. Local preferences domestication by International Center for Research in useful plant species and even plant parts of the same in Agroforestry (ICRAF) scientists, is nowadays well species are known to differ geographically and in integrated into the rural faming systems of Cameroon. relation to ethnic group (Assogbadjo et al. 2012; Sop Its sale generates over 8 million US dollars annually in et al. 2012). Local preferences are also related to local Cameroon only (Tchoundjeu et al. 2013). The African abundance of certain plant species and other useful pear (Dacryodes edulis (G. Don) H. J. Lam), another plant species being present in an area (Wickens and IFT of the Central African rainforest, is also cultivated Lowe 2008). Economical purposes are other leading and traded in the regional markets (Tchoundjeu et al. preferences nowadays. 2002). A recent exhaustive review on agroforestry in the Domestication can be defined as a human-induced tropics suggested that the main objective and chal- change in the genetics of a plant to bring it into wider lenge for the next decade (2012–2021) in Africa is the cultivation through a farmer-driven or marked-led scaling up of successful agroforestry tree domestica- process (Harlan 1975), although domestication first tion programs (Leakey et al. 2012). However, these targets changes in phenotypes. There are several successful programs cannot be scaled up if local and ‘degrees’ of domestication, from being only uncon- regional preferences are not in agreement with current sciously managed and selected to being dependent on selected ‘priority species’. Thus, there is a need to humans for its continued existence (Harlan 1975). In assess in a cost-effective way which IFTs could be the past few years, several programs have been promoted in a specific area. Species priority setting by focused on IFTs domestication, especially in the farmers is considered to be the first step in the African drylands (see Ræbild et al. 2011). A few participatory approach to successfully domesticate species, identified as ‘priority’ trees, have been high value agroforestry species (Akinnifesi et al. subjected to great research. In the African savannah 2008). and drylands these comprise Adansonia digitata L., Different approaches have been used for IFT Sclerocarya birrea (A. Rich.) Hoscht., Ziziphus mau- priority setting (e.g. Akinnifesi et al. 2008). A ritiana Lam., Balanites aegyptiaca (L.) Delile, Ta- common approach is a survey of farmer preferences, marindus indica L. and Uapaca kirkiana Mu¨ll. Arg. and sometimes, a valuation survey is also conducted, (Ofori et al. 2014). In dry West Africa, Parkia which makes the process more costly. It has already biglobosa (Jacq.) R. Br. ex G. Don. and Vitellaria been identified that this approach has an important paradoxa C. F. Gaertn. are also included (Ræbild et al. weakness as it does not explicitly assess the market 2011) while in the miombo woodlands of southern potential of different species and products (Akinnifesi Africa Parinari curatellifolia Planch. ex Benth. and et al. 2008). Therefore, apart from assessing farmers’ Strychnos cocculoides Baker are also considered preferences, a market survey is also needed. More- priority species (Akinnifesi et al. 2008). over, as more than 90 % of the marketed IFTs products Interestingly, the number of ‘priority’ trees for the still come from the wild (Akinnifesi et al. 2008), field African rainforest zone seems lower than in savannah observations on harvesting techniques and abundance and drylands. While the World Agroforestry Center in the wild are also of key importance as IFTs (WAC) focus its research on I. gabonensis, I. wom- products’ harvesting often alters the rate of survival, bolu, D. edulis, Ricinodendron heudelotii (Baill.) growth, and reproduction of harvested individuals Heckel and Chrysophyllum albidum G. Don (Ofori (Gaoue and Ticktin 2007). Finally, as there is often a 123 Genet Resour Crop Evol (2017) 64:745–760 747 gap between current management and farmers’ adop- coastal areas. The average temperature is 26 °C, with tion of domesticated trees, it is also relevant to discuss little annual variation, and the relative humidity with local farmers both current management tech- exceeds 80 % for most of the year. The interior plains niques and reasons behind them. In this study a or lowlands, which make up most of the country, used compound ranking system to score these different to be covered with lowland moist evergreen high criteria was used. forest. Nowadays they are mainly covered of fallows In the field of species priority setting for efficient of different ages and most old-growth forest left is conservation and use, several authors have used a confined to protected areas such as national parks (NP) similar approach. For example Brehm et al. (2010) and forest reserves (FR). However, because of finan- assessed priority crop wild relatives (CWR) and Wild cial and human constraints, most FR are not actually Harvested Plants species for conservation in Portugal, protected on the ground (Cuni-Sanchez 2012, pers. using four methods (point scoring procedure, point obs.). The only protected areas where law is reinforced scoring procedure with weighting, compound ranking are those receiving support from external donors: e.g. system and binomial ranking system) to score differ- Gola Forest National Park (GRNP) in the eastern ent criteria, among which were: native