Concern about the functioning of the world's ecosystems has become commonplace, in the scientific literature as well as in everyday parlance. Climate change, loss of biological diversity, chemical pollution, land use changes, and the spread of exotic species are all discussed in connection with the perceived or anticipated degradation or destruction of ecosystems, or at least with an impairment of their functioning. While attention has been focused in the past mostly on the fate of specific processes relevant to human life (such as clean water or the maintenance of food production) or specific valued species, the emphasis has shifted increasingly towards a broader perspective, namely that of the whole ecosystem. Since about the early 1990s, ecosystems and their functioning have become major targets of conservation and management, accompanied by biodiversity as the other major broad-scale conservation focus. Today, both conservation aims are embodied in national and international management strategies, such as the variety of ecosystem management approaches (e.g. Yaffee et al., 1996; Boyce and Haney, 1997) or the Convention on Biological Diversity (including also an ‘Ecosystem Approach’ as a cross-cutting issue), and the various regional and national strategies that are still newly developed. These trends have also triggered a large amount of scientific research related to these fields, which vice versa reinforced the political processes. The concept (or at least the term) ‘ecosystem functioning’ (also ‘ecosystem function’) has thus become a major topic of ecological research during the last decades, especially in connection with biodiversity research.