West African mixed farming systems as meta-ecosystems: A source-sink modelling approach

Bisson Anne, Boudsocq Simon, Casenave Céline, Barot Sébastien, Manlay Raphaël, Vayssières Jonathan, Masse Dominique, Daufresne Tanguy. 2019. West African mixed farming systems as meta-ecosystems: A source-sink modelling approach. Ecological Modelling, 412:108803, 17 p.

https://doi.org/10.1016/j.ecolmodel.2019.108803

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

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Quartile : Q2, Sujet : ECOLOGY

Liste HCERES des revues (en SHS) : oui

Thème(s) HCERES des revues (en SHS) : Economie-gestion

Résumé : Nutrient availability is a major limitation of the production of West African mixed farming systems. The fertility of these systems was traditionally sustained by fallowing, and nutrient transfers by livestock from savanna to croplands. However, demographic growth and socio-economic constraints require the agro-ecological intensification of these systems. To understand how agricultural practices and landscape management affect crop production, we built a meta-ecosystem model of nitrogen stocks and fluxes, and we examined different scenarios of fallow management with or without livestock. Our results suggest that crop production is highly dependent on the source-sink dynamics of nitrogen. Without livestock, maximum crop production is obtained for an intermediate duration of fallowing, highlighting a trade-off between space devoted to production (cropland) and space devoted to fertility restoration (fallow). In presence of livestock, crop production is maximum for a shorter duration of fallowing; it is markedly higher with than without livestock. This result highlights the positive roles of livestock and fallows as pumps (vectors) of nitrogen from savanna rangeland to cropland, and from fallow land to cropland, respectively. However, it also highlights the negative relationship between livestock presence and fallowing, suggesting that the optimal configuration of livestock and fallow management is highly context-dependent. Overall, we argue that the meta-ecosystem approach is particularly relevant for the study of agro-ecosystems characterized by high spatial heterogeneity. This work can be seen as a first step toward an alternative approach, integrating tools from theoretical ecology for the study of agro-ecosystems which functioning strongly depends on spatial organisation.

Mots-clés Agrovoc : système d'exploitation agricole, système agropastoral, recherche sur les systèmes agraires, relation source puits, modélisation des cultures, bétail, approche écosystémique

Mots-clés géographiques Agrovoc : Afrique occidentale

Mots-clés libres : African mixed-farming system, Meta-ecosystem model, Fallow, Nitrogen, Livestock, Crop production

Classification Agris : E90 - Structure agraire
F08 - Systèmes et modes de culture
U10 - Informatique, mathématiques et statistiques

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

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