The article discusses the integration of plant functional diversity (FD) into ecosystem service (ES) assessments. It emphasizes the role of FD in modulating ecosystem properties (EP) that are directly relevant to ES. The authors propose a systematic framework to understand how land cover changes affect these EP through FD modifications. They highlight the importance of considering both the mean and distribution of plant trait values, as well as the relative abundance of species, in predicting EP and ES. The framework is illustrated with examples from the literature and applied to a grassland system in the central French Alps, where FD influences the provision of ES important to local stakeholders. The study shows that FD can significantly affect EP, particularly through the mass ratio hypothesis, which suggests that ecosystem functioning is mainly determined by the trait values of dominant contributors to plant biomass. The authors also discuss the importance of considering different FD components, such as functional divergence, in predicting EP and ES. The framework allows for the testing of various combinations of FD and abiotic factors to reduce uncertainty in EP predictions. The study concludes that integrating FD into ES assessments is crucial for understanding the impacts of global environmental change on ecosystem services. The framework provides a new approach at the interface of land change science and fundamental ecology.The article discusses the integration of plant functional diversity (FD) into ecosystem service (ES) assessments. It emphasizes the role of FD in modulating ecosystem properties (EP) that are directly relevant to ES. The authors propose a systematic framework to understand how land cover changes affect these EP through FD modifications. They highlight the importance of considering both the mean and distribution of plant trait values, as well as the relative abundance of species, in predicting EP and ES. The framework is illustrated with examples from the literature and applied to a grassland system in the central French Alps, where FD influences the provision of ES important to local stakeholders. The study shows that FD can significantly affect EP, particularly through the mass ratio hypothesis, which suggests that ecosystem functioning is mainly determined by the trait values of dominant contributors to plant biomass. The authors also discuss the importance of considering different FD components, such as functional divergence, in predicting EP and ES. The framework allows for the testing of various combinations of FD and abiotic factors to reduce uncertainty in EP predictions. The study concludes that integrating FD into ES assessments is crucial for understanding the impacts of global environmental change on ecosystem services. The framework provides a new approach at the interface of land change science and fundamental ecology.