Spatially Explicit Mapping of Land-Use Scenarios and Ecosystem Services Interactions of the Sokoto-Rima Basin

Understanding the dynamics of the semi-arid ecosystem of West Africa has become much more crucial. This ecosystem has undergone dramatic changes over the past decades driven by intensified agrarian land-use, climate change and conflicting land management policies with antecedent impacts on ecosystem services (ES). This succinctly captured the physical nature of the Sokoto-Rima basin of north-western Nigeria. The aimed of this study therefore was to reveal the impact of land management scenarios and climate change on the spatiotemporal variations of ES on the Sokoto-Rima basin. In this study, we quantified five ES namely crop production (CP), seasonal water yield (SWY), habitat quality (HQ), carbon storage and sequestration (CSS) and nutrient regulation efficiency (NRE) using InVEST model for the years 1992, 2002, 2012, and 2015. Pairwise correlation coefficients were utilised for estimating ES synergies and trade-offs across three pre-selected land management scenarios and climate change. Results showed that cropland dominated the Sokoto-Rima basin with a gain of 936.79 km² (1.38%) while grassland decimated by 804.57 km² (-8.84%) between 1992 and 2015. The climate change pattern of the basin showed a localised bi-climatic trend of warning-wetting and warning-cooling spells across the area. The proposed Great Green Wall project returned the most substantial correlation values amongst the ES pairwise comparisons with HQ/CP (r = 0.5138) recording the highest synergy value while CSS/NRE (r = -0.0279) returned the least trade-off value. This study will intensify the understanding of the diverse relationships between land management policies and multiple ES interactions within the semi-arid ecosystem of West Africa.