Using quantitative methods to understand how ecological systems operate and influence each other, this textbook presents a complete and practically applicable ecosystems theory. The book is built on 14 principles for ecological systems, including the general application of energetics principles in systems ecology. Written by an internationally recognized expert, this work provides readers with a thorough understanding of how ecosystems work and how they react to disturbances such as pollution. The holistic systems ecology described has a wide application in conservation biology, ecological modeling, assessment of ecosystem health and sustainability, and ecotechnology.