Sahelian woody communities are endangered by regeneration impoverishment in three land management types

Dendoncker Morgane, Vincke Caroline, Ndianor Ramata, Diouf Abdoul Aziz, Miehe Sabine, Ngom Daouda, Taugourdeau Simon. 2024. Sahelian woody communities are endangered by regeneration impoverishment in three land management types. New Forests, 26 p.

Résumé : Monitoring regeneration in woody communities and understanding the drivers of its success is crucial for gaining insight into the long-term persistence of trees in African drylands, where they play key socio-ecological roles. While fire, grazing and water availability are key factors for regeneration in these ecosystems, seed arrival, germination and seedling recruitment are still poorly documented under natural conditions in the West African Sahel. Tree planting is commonly carried out in West Africa to promote regeneration. The cost is considerable, the success is variable and its influence on spontaneous regeneration is unknown. We conducted a field inventory to ascertain the regeneration ability of woody communities in a Sahelian savanna in three land management types (plantations, communal grazing, old enclosures) to determine (i) the proportion of the different regeneration mechanisms; (ii) the influence of adult trees; (iii) the influence of management type and topography and (iv) their temporal dynamics. We first showed that regeneration diversity was poor, with half of the adult species not recorded in the regeneration phase. Secondly, regeneration mostly came from true seedlings compared to resprouting. Thirdly, adult communities were found to greatly influence regeneration density and composition. Fourthly, topography proved to influence regeneration density, whereas we observed little effect of the land management type. Lastly, historical data highlighted a steep decline in regeneration density over recent decades. These results raise questions about the persistence of woody vegetation in Sahelian savannas and highlight the need to protect large trees in suitable microsites, such as topographic depressions, to promote regeneration.

Mots-clés Agrovoc : composition botanique, régénération naturelle, gestion foncière, plante ligneuse, pastoralisme, pâturage, communauté végétale, savane

Mots-clés géographiques Agrovoc : Sénégal, Sahel

Mots-clés libres : Sahel, Woody vegetation, Regeneration, Pastoralism, Plantation, Dynamics

Classification Agris : F40 - Écologie végétale
K70 - Dégâts causés aux forêts et leur protection
F62 - Physiologie végétale - Croissance et développement

Champ stratégique Cirad : CTS 2 (2019-) - Transitions agroécologiques

Agences de financement européennes : European Commission

Projets sur financement : (EU) Development Smart Innovation through Research in Agriculture, (EU) Sequestration and Green-house Gas Emissions in (Agro) Sylvopastoral Ecosystems in the Sahelian CILSS States

Auteurs et affiliations

• Dendoncker Morgane, UCL (BEL) - auteur correspondant
• Vincke Caroline, UCL (BEL)
• Ndianor Ramata, UCAD (SEN)
• Diouf Abdoul Aziz, CSE [Centre de suivi écologique] (SEN)
• Miehe Sabine
• Ngom Daouda, UCAD (SEN)
• Taugourdeau Simon, CIRAD-ES-UMR SELMET (SEN) ORCID: 0000-0001-6561-3228

Source : Cirad-Agritrop (https://agritrop.cirad.fr/609230/)

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