Effects of land use change on ecosystem services in Africa's Great Green Wall Initiative (GGW) for dryland restoration

Abstract

Dryland ecosystems worldwide face substantial degradation due to adverse climatic conditions and unsustainable land practices. This is particularly evident in Africa's Sahel region, where extensive land degradation and desertification pose significant challenges to local livelihoods and socio-economic stability. To address this issue, the Great Green Wall Initiative (GGW) aims to restore over 100 million hectares of degraded land to counter desertification and support rural communities.Here we assess how land use changes have altered ecosystem services within GGW implementation areas. We analyzed the spatiotemporal characteristics of land use change using the MODIS-Global Land Cover product from 2007 to 2019. Based on remote sensing data and established geospatial models, we evaluated five ecosystem services, namely carbon sequestration, soil conservation, sand fixation, water regulation, and food provision. We explored trends in ecosystem service changes, identified spatial clusters of high and low values, and evaluated synergies and trade-offs among these services by Pearson's coefficient and the bivariate Moran’s I method. The result showed that the level of various ecosystem services in GGW areas is heterogeneous, with a large spatial distribution. High values of ecosystem services are found in Burkina Faso, southern Nigeria and eastern Ethiopia. Synergies between ecosystem services are dominant, with the strongest synergies between carbon sequestration and soil conservation. Carbon sequestration and water regulation were clustered, but there were trade-offs with food provision. We quantified the contribution of land use to the changes in ecosystem services through the calculation of the Ecosystem Service Contribution Index (ESCI). The expansion of farmland and desertification have had significant negative impacts on ecosystem services and grassland conversion. This assessment provides critical insights into the efficacy of restoration efforts and aims to offer guidance for informed decision-making in sustainable management practices for dryland ecosystems.