ABSTRACT
Functional endpoints have been advocated since they integrate the effects on lower levels of biological organisation, and indicate the severity of a perturbation; changes of the ecosystem would be acceptable as long as the functions are maintained.
This review summarizes the information available for outdoor model ecosystems. As functional endpoints are considered measures of the pools of non-living materials and the intensities of processes in which the organisms are involved. Examples are oxygen and carbon concentrations and production-consumption as reflected by changes in oxygen concentration and pH. Nutrient concentrations and nutrient fluxes are also frequently studied.
Functional endpoints are rarely more sensitive than structural ones, but they are an indicator of ecosystem health. Functional endpoints indicate the limit of functional redundancy of the ecosystem.
