When this book was first published in 1991, developments in the study of theoretical ecology had led to the appearance of more complex concepts in ecosystem theory. As a result, ecosystems may be viewed as networks of coexisting living organisms and their non-living milieu which result in the transfer and transformation of material, energy and information. This book presents a comprehensive overview of these ideas, bringing together in a single volume a diverse range of viewpoints and approaches. Similarities and difference between these viewpoints are clarified, controversial issues addressed and problems for investigation identified. Because of its diverse and comprehensive nature, a wide range of ecological and environmental scientists, including theoretical as well as field ecologists, modellers, managers and policy makers, will find this book an invaluable asset in dealing more effectively with truly complex and realistic ecosystems networks. The book is also intended for use by graduate students in their advanced study.