* The prominent new place of ecosystem services in environmental policy, land management and land planning requires that the best ecological knowledge be applied to ecosystem service quantification. Given strong evidence that functional diversity underpins the delivery of key ecosystem services, assessments of these services may progress rapidly using a trait-based approach. * The trait-based approach shows promising results, especially for plant trait effects on primary production and some processes associated with carbon and nitrogen cycling in grasslands. However, there is a need to extend the proof of concept for a wider range of ecosystems and ecosystem services and to incorporate not only the functional characteristics of plants but those of other organisms with which plants interact for the provision of ecosystem services. * The five papers in this Special Feature illustrate how some of the key conceptual and methodological challenges can be resolved, and provide a range of case studies across three continents. Relevant plant functional traits depict different axes of variation including stature, the leaf economics spectrum, and associated or independent variations in root or stem traits. The application of the trait approach to ecosystem processes underpinned by interactions between plants and other biota is illustrated for soil micro-organisms and granivorous invertebrates. There is strong evidence for the biomass ratio hypothesis (i.e. prevalent effects of the traits of dominant species through the community-weighted mean), along with less prevalent and more complex effects of heterogeneous trait values between species (i.e. functional divergence). * Synthesis. Together, the five papers in this Special Feature illustrate how trait-based approaches may help elucidate the complexity of ecological mechanisms operating in the field to determine ecosystem service delivery. To address scientific and management questions about the provision of multiple services, progress is needed in understanding how functional trade-offs and synergies within organisms scale up to interactions between ecosystem services. Service-oriented ecosystem management within the context of global change, or ecological restoration, remains a major challenge, but trait-based understanding opens new avenues towards more generic, integrated approaches.
