Résumé
The concern for damage to nature has led to the emergence of a set of techniques for ecosystem services valuation (ESV) in the late 1960’s. Not surprisingly, the meaning and reliability of ESV techniques themselves are subject to growing scientific debate. The current discussions has primarily focused on six issues: i) the complex relations between ecosystem functions and services, ii) the link between ESV and payment mechanisms, iii) the definition of a meaningful and operational classification of ecosystems services, iv) the link between values and economic valuation, v) the incommensurability debate and, vi) the limits of cost benefit analyses when applied to ecosystem valuation. We begin by reviewing these issues. Then we will give a few examples of valuations of particular ecosystem services or conservation programmes, that highlight both the challenge of placing ESV in a spatially explicit framework and, the so-called “environmentalist paradox”.