The growing use of the concept of ecosystem services generally leads to the observation that the costs and benefits of these services are not sufficiently taken into account by public and private actors. To remedy this situation, many experts – well beyond the circle of economists – recommend not only developing payment for ecosystem services (PES) mechanisms, but also putting prices, or monetary values, on ecosystems. However, while economic approaches to the conservation and sustainable use of biodiversity being currently on the rise (particularly in the wake of the study led by P. Sukhdev), they actually go back several decades. Although different examples of economic assessments or of PES exist throughout the world since the 1970s, the fact that they have remained
relatively confidential, or at least exceptional, calls for a detailed study of both the advantages and disadvantages and the theoretical and practical obstacles to the possibility of them coming into widespread use. IDDRI focused its efforts on these issues, which will remain a key
area of its activities.

A study was conducted in partnership with the United Nations Economic and Social Commission for Asia and the Pacific (UNESCAP ) on payment for ecosystem services mechanisms. Based on an in-depth analysis of the case of Vietnam, a methodological framework was developed, aimed at supporting national governments in their efforts to implement PES.

Furthermore, an important research project was launched on the role of economic evaluations of biodiversity and ecosystem services in decision-making processes, both public and private. Indeed, besides the methodological issues, which are unlikely to be fully resolved one day, the role actually played by these assessments in decisionmaking processes (in terms of development, infrastructure
choices, the protection of nature, etc.) and in negotiations (including those on setting up PES) remains rather mysterious. In partnership with private companies, public organisations and NGOs, IDDRI has therefore set itself the objective of documenting and analysing what is at stake in
the mobilisation of these “figures” by different categories of actors, based on case studies that make it possible to assess their usefulness, their development potential and the conditions of their use.