Tree populations show low regeneration of valued species in West Africa

Lykke Anne Mette, Romer Nanna, Gonzalez Patrick, Glele Kakaï Romain Lucas, Rabiou Habou, Amegnaglo Kossi Béssan, Ganaba Souleymane, Sambou Bienvenu, Niang Fatimata, Herault Bruno, Guuroh Reginald Tang, Ouoba Paulin, Yaméogo Jérôme, Traoré Lassina, Sinsin Brice Augustin, Amahowe Ogoudje Isidore, Bay Signe S., Houehanou Thierry Dèhouégnon, Houessou Laurent G., Gouwakinnou Gérard N., Yetein Marius H., Tankoano Boalidioa, Ouedraogo Amadé, Ouédraogo Issaka, Taita Paulette, Amani Bienvenu H.K., Coulibaly Brahima, Kouyate Amadou Malé, Van Damme Patrick, Vanhove Wouter, Mahamane Ali, Bonache Carolina, Sambou Simon, Soumana Idrissa, Amani Abdou, Maârouhi Maman Maârouhi, Barfod Anders S.. 2025. Tree populations show low regeneration of valued species in West Africa. Biological Conservation, 301:110891, 9 p.

https://doi.org/10.1016/j.biocon.2024.110891

Article de revue ; Article de recherche ; Article de revue à facteur d'impact

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Résumé : Tree populations have declined substantially in West Africa in recent decades, raising concerns since trees provide numerous ecosystem goods and services. Regional information on the population status of tree species could guide more effective conservation and regeneration of natural vegetation. Here, we report results of the first regional analysis of tree population structure across the Sahel and Sudan zones, a meta-study of vegetation inventories, including 23,586 individual trees sampled across nine countries. We evaluated current status and forecast future trends of 16 species and one genus of trees of ecological and socio-economic importance. Size class distribution (SCD) reflects the population structure of an individual species and can provide early warning of composition change and population decline. SCD is analysed widely at a local scale, but analysis at a regional scale is needed to detect widespread population changes. Many native species lacked trees in the smaller size classes, implying unsustainable populations and future decline. Some species show sound regeneration at the regional scale, but high variation among sites. Eight species, including Adansonia digitata and Afzelia africana, show regional declines in regeneration and risks of future extirpations. Four of these severely lack regeneration. Protected areas show higher tree regeneration, but protected status did not assure good regeneration. Our results identify priority tree species across West Africa, indicate a more urgent need for conservation and regeneration of native tree species, and highlight the benefit of effective conservation. More widespread protection could increase tree populations, conserving biodiversity, and ecosystem services essential for people's livelihoods.

Mots-clés Agrovoc : régénération naturelle, dynamique des populations, services écosystémiques, gestion des ressources naturelles, Adansonia, conservation des ressources, biodiversité, aménagement du territoire, espèce en danger, Afzelia africana, protection de la forêt