Ecosystem services from woody vegetation on agricultural lands in Sudano-Sahelian West Africa

Investment in woody vegetation to counter land degradation and improve livelihoods is increasing, primarily revitalized by efforts to enhance carbon sequestration and climate change adaptation. Sudano-Sahelian West Africa is in focus for several interventions to increase woody vegetation for improved livelihoods. However, the knowledge on how woody vegetation maintains landscape productivity and contributes to livelihoods is widely scattered across different scientific fields. Here we review different bodies of literature including a total of 30 species of woody vegetation. We use ecosystem services as a lens to integrate knowledge about how woody vegetation affect ecosystem processes and contribute to livelihoods. We find that the majority of the species generate multiple provisioning ecosystem services. Medicinal uses, contribution to fodder for livestock and importance for human nutrition are reported for almost all species. Regulating ecosystem services are studied for a more narrow set of species. There are mainly positive or no effects on soil nutrients, soil carbon and soil water content. The overall effect of woody vegetation on crop yields is mediated through multiple processes and shows both positive and negative effects. The majority of studies are focused on effects of individual elements of woody vegetation, with very limited landscape scale analyses. Differences between beneficiaries of ecosystem services are only discussed in a few studies, and only in relation provisioning services. Therefore, future studies need to address landscape scale effects and how the benefits of ecosystem services are distributed among beneficiaries, to provide knowledge that is even more relevant for interventions that aim to enhance climate mitigation and adaptation, ecosystem restoration, as well as poverty alleviation. (C) 2014 Elsevier B.V. All rights reserved.