ABSTRACT
Although policy makers and managers are keen on scientific measures of ecosystem health, stability, resilience, resistance, productivity and other properties representing positive values, ecosystems are, by nature, open, dynamic and constantly changing. Contemporary ecology and social ecological economics are faced with the dilemma of delineating ecosystems and simplifying their complexity to make them intelligible in order to address their mismanagement while accounting for the reality of their biophysical structure and functioning. This dilemma produces two extreme postures depending on how ecosystems are conceived. At one extreme, when considered as irreducible and fundamentally complex systems, ecosystems risk becoming excessively abstract and arbitrary conventions with vague, or no, scientific grounding. At the other, when reduced to some mechanical aggregation of physicochemical phenomenon, ecosystems risk losing their specificity as biological phenomena. Any ecological system is best viewed as a subsystem of a wider environment. Therefore, a practical approach to ecosystem understanding lies in the identification of the limits of the subsystems and of the wider environment (their distinctiveness) as well as in the recognition of their mutual limitations (their reciprocal influence).
