Incorporates the results of the program on ecosystem experiments conducted by the Scientific Committee of Problems of the Environment. Features research papers submitted at Mitwitz, Germany and Washington, D.C. The objective of this compilation of papers is to explore the potential of ecosystem experimentation as a tool for understanding and predicting changes in the biosphere. Areas investigated include deforestation, desertification, El Nino phenomenon, acid rain, watersheds, wetlands, aquatic and climatic changes.