Néré (Parkia biglobosa)

by Barbara Vinceti

Background

Parkia biglobosa is a medicinal and food tree species with a wide natural distribution in sub-Saharan Africa, between 4°N to 15°N of latitude, over 20 African countries, from Senegal to Uganda. It is well represented in traditional agroforestry systems (parklands) but the species is subject to unsustainable exploitation, lack of regeneration and ageing, due to clearing of the land for agriculture, the demand for fuelwood, mining, environmental degradation, the effects of global environmental changes, combined with the high demand of its edible and medicinal products. Some tree populations are highly threatened in large parts of its range, so they are disappearing or significantly declining in density. Improved tree management practices, such as direct sowing, protection of natural regeneration and planting, are not sufficiently promoted (Ræbild et al., 2012).

About the plant

Parkia biglobosa (Jacq.) G.Don, commonly called “néré” (French) or “African locust bean”, is a fruit tree species belonging to the Fabaceae. Its natural range extends across the Sudanian savannas and partly in the northern Sahelian zone, characterized by annual rainfall between 700 and 2,600 mm. In Burkina Faso, tree population density of the species varies between less than one tree/ha in the sub-Sahelian zone to up to 25 trees/ha in the southern part of the Sudanian zone (Ouedraogo, 1995). In addition to its ecological importance, the species plays an important economic and social role for rural communities, providing food, medicine, fodder, fuel wood, and soil fertilization, being a nitrogen-fixing legume tree (Ouedraogo, 1995; Hall et al., 1997). The species is melliferous and widely valued in traditional beekeeping, it is a source of tannins for artisanal use (Ouedraogo, 1995), it supplies fodder, and its leaves are incorporated into soil as green manure.

The critical role of Parkia biglobosa in local diets

Néré plays a significant role in the diet of rural communities across its range. The most valuable part of the tree are the pods. The seeds are crushed, fermented and moulded into balls, used as a condiment (soumbala or dawadawa), usually combined with grain-based food items, in traditional soups and stews, consumed with sorghum or millet dumplings, or with porridge. Soumbala can be stored for long periods in earthenware pots and is an important source of proteins, essential amino acids (e.g. lysine), vitamins (e.g. riboflavin and vitamin C), essential fatty acids and minerals (Guissou et al., 2020; Termote et al., 2020), and a key integration of diets commonly based on carbohydrate staples (e.g., yams and cassava). Besides its nutritional value, this fermented and tasty condiment has a great importance in West African culture, being used in occasions of all major rituals. The practice of using fermented locust beans has a long tradition that seems to date back at least to the fourteenth century (Sina and Traore´ 2002).

The sweet pulp surrounding the seeds is eaten fresh or made into sweets and drinks. It is a source of energy and nutrients (e.g., glucids, proteins, carotenoids, vitamins A, B, C, and oligo-elements), and is important as mineral supplement (Dao et al., 2021; Termote et al., 2020).

Women are the main harvesters of néré pods and obtain both nutritious ingredients to feed their families and income from the sale of soumbala (Kronborg et al., 2013; Sabiiti and Cobbina, 1992). Traditionally soumbala was prepared for domestic use, but women entrepreneurs have been increasingly involved in its production, trade and distribution (Kronborg et al., 2013).  

Role in social interactions

Status of residence and gender are key variables that affect the management of P. biglobosa. In Burkina Faso, based on customary tenure, native farmer householders have secure access rights to land and each male descendent is entitled to obtain a portion of the land under control of the lineage (Pehou et al. 2020). On the other side, male heads of migrant households can borrow land from native farmers, but do not acquire rights to use the trees already growing on the land. Pastoralists are also excluded from secure rights to land and trees.

Women do not own nor inherit land and cultivate much smaller plots than men (Ouedraogo et al. 2005). However, although trees are under the control of men, women held use rights to P. biglobosa products, organize the harvest of its pods, their processing and sale.

Recent research has described in detail the ways the species connects with a system of power relations, affects flows of access rights and benefits associated with its use, and determines multiple social interactions amongst a wide range of local actors (Djoudi et al., 2022). The species does not only provide ecosystem services but contributes to creating and shaping social relations and interactions among diverse identities, social positions, and landscape histories.

Interactions among social entities through P. biglobosa are not determined by one single factor but by a combination of different social attributes, such as settlement history, ethnicity, gender, social class, and marital status (Cho et al. 2013; Djoudi et al. 2016). Furthermore, certain rights appear not to be rigid but rather negotiable, as the benefit from P. biglobosa products are not obtained through formal and fixed access, but through adaptable social mechanisms that involve also community members with no customary rights to the products of this species.

Conservation

In Burkina Faso and in other West African countries P. biglobosa is formally protected by national legislation and cutting is prohibited. Nevertheless, conservation efforts need to be strengthened, given the biotic and abiotic pressures affecting future availability of this resource. In the recent years, a significant amount of information has been generated to support the development of a conservation strategy based on complementary in situ and ex situ conservation approaches, taking into account farmers' perceptions together with morphological and molecular variables.

Farmers appear to have an active role in shaping the intraspecific diversity of the species, also affecting its overall spatial distribution, density, and structure of tree populations. The species is retained in farmers' fields when these are cleared for agriculture, but also actively planted. Farmers have well defined criteria to identify 'plus' trees from which to obtain reproductive material.

The National Tree Seed Center (CNSF) has identified and phenotypically characterized 48 stands of P. biglobosa, with 30 - 50 reproductive individuals over 10 - 50 ha, where trees are managed in their natural habitat to be used as seed sources, with involvement of local communities in the monitoring and management of the stands, to ensure their conservation (Lompo et al., 2017). Although the species is officially protected, those seed stands located within protected areas are more efficiently safeguarded. 

Six seed zones, defined base on ecological, climatic and administrative parameters, have been delineated in Burkina Faso for all tree species to guide seed transfer. Existing seed stands of P. biglobosa cover only three seed zones, excluding northern areas of the country due to absence or low density of the species.

A range-wide phylogeographic study has brought improved understanding on the evolutionary history of the species and the present patterns of genetic variation (Lompo et al., 2018). The study led to the identification of three main gene pools and to locate a hotspot of genetic diversity in Central West Africa. These are all crucial elements for the development of a genetic conservation strategy and breeding programmes that take into account expected future climatic changes.

Successive seed collection campaigns in the late 80s’ and early 90s’ by the CNSF and partners and contributed to the establishment of ex situ collections covering the entire range, stored at the CNSF seed bank, and of provenance and progeny trials (Lompo et al, 2017), which have been assessed over time (Ouedraogo et al., 2012).

Optimal seed harvesting and handling procedures have been developed. Testing on seed behavior indicated that the seeds of P. biglobosa can be considered orthodox, with a significant loss of vitality after 20 years of storage (Millogo, 2014). Direct sowing is the most practical technique used for the rejuventation and improvement of traditional agroforestry systems.

Concluding remarks

Recent evidence has shown how native tree species of high cultural value, like P. biglobosa, represent more than well-defined and measurable ecosystem functions and services, and their loss implies also the disappearance of fine-tuned social and environmental relationships that reflect a diversity of identities and social positions. Tree species like P. biglobosa mediate social dynamics and enable different members of rural communities to negotiate and adapt their livelihoods to rapidly evolving social and environmental contexts. Therefore, their conservation is crucial and the inclusion of key native species in restoration efforts should be preferred to a substitution with others.

Being one of the most appreciated indigenous food tree species in Burkina Faso and the broader West African region, P. biglobosa has great potential for the implementation of nutrition-sensitive forest landscape restoration (Vinceti et al., 2022). To support appropriate selection of tree planting material, both at regional and country level, species-specific seed zones and seed transfer guidelines should be developed, using approaches that combine molecular information and multivariate regression trees, to effectively contribute to the success of forest landscape restoration efforts in the face of climate change. In addition to ecological and genetic information, social and cultural aspects, such as indigenous knowledge and preferences, should be taken into account in the shaping of future breeding efforts.

Further population genetic studies, especially designed to assess the species vulnerability to fragmentation and the influence of land use changes on its viability, are needed (Lompo et al., 2020). Although P. biglobosa seeds are orthodox, they lose their capacity to germinate after 20 years so vegetative propagation techniques such as cutting, layering and grafting need to be optimized in order to develop clone banks of selected desirable traits.

Finally, considering the broad spatial distribution of P. biglobosa, a strategy for the conservation and sustainable use of its genetic resources should be developed on the basis of a multi-country, coordinated international effort.

Click here to download a summary table of the case study.

References

Cho S, Crenshaw Williams K, McCall L. (2013) Toward a field of intersectionality studies: Theory, applications, and praxis. Signs 38(4): 785–810

Dao, A. S., Parkouda, C., Traoré, M. E., Aimée, W. G., Barbara, V., Céline, T., Mattia, M., & Bassolé, I. H. N. (2021). Comparison of chemical composition of fruit pulp of Parkia biglobosa (Jacq.) Benth from differents ecoregions. African Journal of Food Science, 15(1), 26–32. Available here.

Dedehou V, Olounlade´ P, Alowanou G, Azando E, Hounzangbe ´-Adote´ S (2016) A review on medicinal plants of Parkia biglobosa (Mimosaceae-Fabaceae) and Pterocarpus erinaceus (Leguminosae-Papilionoidea). JMPS 4:132–137

Djoudi, H., Locatelli, B., Vaast, C., Asher, K., Brockhaus, M., & Basnett Sijapati, B. (2016). Beyond dichotomies: Gender and intersecting inequalities in climate change studies. Ambio, 45(S3), 248–262. Available here.

Djoudi, H., Locatelli, B., Pehou, C., Colloff, M. J., Elias, M., Gautier, D., Gorddard, R., Vinceti, B., & Zida, M. (2022). Trees as brokers in social networks: Cascades of rights and benefits from a Cultural Keystone Species. Ambio, 1–18. Available here.

Guissou, A. W. D. B., Parkouda, C., Vinceti, B., Traoré, E. M. A., Dao, A. S., Termote, C., Manica, M., & Savadogo, A. (2020). Variability of nutrients in Parkia biglobosa kernels from three geographical regions in Burkina Faso. 14(3), 63–70. Available here.

Hall JB, Thomlinson HF, Oni PI, Buchy M, Aebischer DP (1997) A monograph of Parkia biglobosa. School of Agricultural and Forest Sciences Publication N°9, Bangor, University of Wales, 107 pp.

Kronborg, M., Lykke, A. M., Hien, M., & Balslev, H. (2013). Parkia biglobosa as an Economic Resource for Rural Women in South-western Burkina Faso. West African journal of Applied Ecology, 21(2),95-107. Available here.

Lamien N, Ekue´ M, Ouedraogo M, Loo J. (2011) Parkia biglobosa. African locust bean: conservation and sustainable use of genetic resources of priority food tree species in Sub-Saharan Africa. Bioversity International, Rome

Lompo, D., Vinceti, B., Gaisberger, H., Konrad, H., Duminil, J., Ouedraogo, M., Sina, S., & Geburek, T. (2017). Genetic conservation in Parkia biglobosa (Fabaceae: Mimosoideae) - what do we know? Silvae Genetica, 0(0), 1–8. Available here.

Lompo, D., Vinceti, B., Konrad, H., Gaisberger, H., & Geburek, T. (2018). Phylogeography of African locust bean (Parkia biglobosa) reveals genetic divergence and spatially structured populations in West and Central Africa. Journal of Heredity. Available here.

Lompo, D., Vinceti, B., Konrad, H., Duminil, J., & Geburek, T. (2020). Fine-scale spatial genetic structure, mating, and gene dispersal patterns in Parkia biglobosa populations with different levels of habitat fragmentation. Applications in Plant Sciences, 107(7), 1041–1053. Available here.

Millogo, A.M.D. (2014) Etudes des caracteristiques morphologiques et de la viabilite des semences de Parkia biglobosa (Jacq.) (Jacq.) R. Br. ex G. Don. Germoplasme de conservation à long terme a 4°C. Mémoire de Master (Burkina Faso): Universite Polytechnlque Sde Bobo-Dioulasso. 61 pages. Available here.

Orwa C, A Mutua, Kindt R , Jamnadass R, S Anthony. (2009) Agroforestree Database: a tree reference and selection guide version 4.0 Available here.

Ouedraogo AS. (1995) Parkia biglobosa (Leguminosae) en Afrique de l’Ouest: Biosystématique et Amélioration. Dissertation, Wageningen University, In­stitute for Forestry and Nature Research, IBN-DLO, 205 p

Ouédraogo, H. Edja, M. Koné, D. Thiéba (2005). Étude comparative de la mise en œuvre des plans fonciers ruraux en Afrique de l'Ouest: Bénin, Burkina Faso, Côte d'Ivoire. Les Etudes juridiques en ligne sur FAO, Rome. Available here.

Ouedraogo, M., Ræbild, A., Nikiema, A., Kjær, E.D. (2012). Evidence for important genetic differentiation between provenances of Parkia biglobosa from the Sudano-Sahelian zone of West Africa. Agroforestry Systems, Vol. 85(32):489-503.

Pehou, C., Djoudi, H., Vinceti, B., & Elias, M. (2020). Intersecting and dynamic gender rights to néré, a food tree species in Burkina Faso. Journal of Rural Studies, 76(February), 230–239. Available here.

Ræbild A, Hansen UB, Kambou S (2012) Regeneration of Vitellaria paradoxa and Parkia biglobosa in a parkland in Southern Burkina Faso. Agrofor Syst 85: 443-453. Available here.

Sabiiti, E. N.; Cobbina, J., (1992). Initial agronomic evaluation of Parkia biglobosa in the humid zone of Nigeria. Agrofor. Sys., 17(3): 271-279.

Sina, S. Traoré, S. (2002). Parkia biglobosa (Jacq.) R. In: PROTA (Plant Resources of Tropical Africa), ed. L. Oyen, R. Lemmens. Wageningen, The Netherlands. Available here.

Termote, C., Odongo, N. O., Dreyer, B. S., Guissou, B., Parkouda, C., & Vinceti, B. (2020). Nutrient composition of Parkia biglobosa pulp, raw and fermented seeds: a systematic review. Critical Reviews in Food Science and Nutrition, 1–26. Available here.

Vinceti, B., Fremout, T., Termote, C., Fallas Conejo, D., Thomas, E., Lachat, C., Toe, L. C., Thiombiano, A., Zerbo, I., Lompo, D., Sanou, L., Parkouda, C., Hien, A., Ouédraogo, O., & Ouoba, H. (2022). Food tree species selection for nutrition‐sensitive forest landscape restoration in Burkina Faso. Plants, People, Planet.