Ecological Functions and Socioeconomic Values of Critical Natural Capital as a Measure for Ecological Integrity and Environmental Health

To implement ecological integrity and restore environmental and human health, the concept of “sustainable development” is an important guiding principle. One of the first, but not much cited, references to the concept of “sustainable development” is the one given by IUCN, UNEP & WWF (dy1980) in their World Conservation Strategy: “the management of human use of the biosphere so that it may yield the greatest sustainable benefit to present generations while maintaining its potential to meet the needs and aspirations of future generations”. Since then, many other definitions have been given, for example by the World Commission on Environment and Development in 1987, and at the United Nations Conference on Environment and Development in 1992. Unfortunately, most definitions did not explicitly mention the need to conserve the natural resource base. In its follow-up document to the World Conservation Strategy, Caring for the Earth, IUCN therefore expanded the concept to: “improving the quality of human life while living within the carrying capacity of supporting ecosystems” (IUCN, UNEP, WWF, 1991). An even more precise definition was given recently by Hueting and Reijnders (1998) who defined sustainability as “the use of the vital functions (possible uses) of our biophysical surroundings in such a way that they remain indefinitely available”.