Agroecosystem Resilience and Sustainability of Inland Valleys to Climate Change in West Africa: Benin’s Sudano-Guinean and Guinean Zones Case

Abstract

Inland valleys (IVs) are critical socio-agroecological systems in Sub-Saharan Africa, providing essential ecosystem services (ES) such as provisioning, regulating, supporting, and cultural services. However, these ecosystems face increasing threats from climatic hazards and anthropogenic pressures, undermining their sustainability and crop productivity. This doctoral research investigates the pathways for conserving and optimizing the ecosystem services of Inland valleys in Benin, focusing on the interplay between management approaches, climatic hazards, and smallholder farmers' adaptive strategies. The study employs a mixed-method approach, integrating quantitative and qualitative data from 298 farmers across 41 Inland valleys, as well as biophysical, climatic (1991–2021), socio-economic data from 76 Inland valleys and an agricultural experiment highlighting the smart and undeveloped valley approach, fertilization levels based on RiceAdvicce technology and the standard level of farmers during 2022 and 2023 in Benin's Guinean and Sudano-Guinean zones. The study addresses four specific objectives. First, it analyses the state of ES provided by Inland valleys under different management approaches, identifying Smart Valley as the most effective in delivering provisioning, regulating, and supporting services (with a relative importance index of 0.85, 0.81, and 0.68, respectively), while undeveloped valleys excel in cultural services (with a relative importance index of 0.45). Second, it assesses the vulnerability of Inland valleys to climatic hazards, revealing that drought affects 35% of Inland valleys, primarily in the Sudano-Guinean zone, and is predicted by soil organic carbon, sand content, and the Standardized Precipitation Evapotranspiration Index (SPEI). Flooding affecting 30% of Inland valleys, is more frequent in the Guinean zone and linked to annual rainfall, sand content, and SPEI. Third, it evaluates smallholder farmers' mitigation strategies, highlighting practices such as organic farming, irrigation, and agroforestry for drought, and crop season adjustments and natural fallow use for flooding. These strategies are influenced by market access, extension services, and infrastructure. Fourth, it assesses the impact of management approaches on sustainability and productivity, demonstrating that Smart Valley approaches significantly improve soil moisture (8.62% higher than undeveloped approaches) and rice yields (35.42% higher), with fertilization further enhancing productivity by up to 13.65%. This research provides actionable insights for policymakers and practitioners to promote the sustainable management of Inland valleys, ensuring their resilience and productivity in the face of climate change and anthropogenic pressures.