ABSTRACT
The Millennium Ecosystem Assessment (MA) first stimulated a new and much deeper level of interest in ecosystem services, and this has continued to develop in both research and policy environments. Developments since the publication of the MA in 2005 have been especially rapid, and the framing for ecosystem services has matured, developed and spread into a range of other related areas, although not always with coherence and clarity. Ecosystem services and natural capital are sometimes treated as if they mean the same thing. In fact, because some commentators find the terminology of ecosystem services difficult, there is increasing use of the term 'natural capital' as an equivalent alternative term. Trade-offs among ecosystem services are a recurring research theme. Ecosystem services has its origins in the natural sciences, its adoption in social sciences is far from complete, and the struggle to maintain the necessary interdisciplinarity for the social and ecological systems referred to above remains a challenge.
