This book incorporates the results of a SCOPE (Scientific Committee of Problems of the Environment) program on ecosystem experiments. This program brought together a group of international scientists at Mitwitz, Germany, to evaluate the state of our knowledge on the response of ecosystems to major perturbations. This group reviewed past work in this area as well as proposing priorities for future research for the study of both terrestrial and aquatic ecosystems utilizing experimental approaches. This meeting was followed by a more technical one, held in Washington, DC, dealing specifically with one of the priority experiments established for terrestrial ecosystems, that of determining the response of whole systems to enriched atmospheric CO₂. The results of this latter workshop are included in this volume. The SCOPE ecosystem experiment program still has in progress considerations for the design of ecosystem experiments for estuarine systems.

   This project was initiated to provide guidance to the developing IGBP (International Geosphere Biosphere Program). It is clear that, in order to develop some degree of predictive capacity of the responses of ecosystems to global change, we will have to rely, to some degree at least, on the utilization of the direct experiments on intact ecosystems, as discussed in the introduction and throughout the volume.

   This SCOPE project was supported by the A.W.Mellon Foundation and the German Federal Ministry for Research and Technology. The workshop on CO₂ enrichment experiments was aided by the CO₂ Research Program of the United States Department of Energy and the Electric Power Research Institute. Appreciation is expressed to these organizations, as well as to the many scientists who participated in the program.