Societal demand for multifunctional agricultural landscapes keeps increasing. To promote such landscapes, it is necessary to identify which components of landscape heterogeneity support multiple ecosystem services, as well as levers of action to promote these landscape properties. The social-ecological theoretical framework for multifunctional landscapes has inspired 40 years of research in the Long Term Socio-Ecological Research site of Vallées et Coteaux de Gascogne (VCG), which is part of the LTSER platform ZA PYGAR located in south-west France. Researchers from different domains of the social and biophysical sciences, have worked together in this LTSER site and gained a multidisciplinary understanding of both drivers of VCG landscape dynamics and the role of landscape heterogeneity for multiple ecosystem services. Local features of the VCG and social systems have interacted with global drivers and lead to the maintenance of a high level of landscape heterogeneity. We show how the different components of landscape heterogeneity influence cultural, provisioning, supporting, and regulating services. In collaboration with stakeholders, we developed scenarios to explore possible futures for the VCG landscapes and are now integrating models developed for the VCG to assess the consequences of these scenarios on landscape multifunctionality. This synthesis demonstrates how LTSER sites can be particularly relevant to explore the future of multifunctional agricultural landscapes.