1 Introduction.- 2 Ecosystem Concept: Historical and Present Review of Definitions and Development of Ecosystem Ecology, Ecosystem Management, and Its Legal Framework.- 2.1 Roots of the Ecosystem Ecology Concept.- 2.2 Roots of Management.- 2.3 Ecosystem Management.- 3 Tools and Knowledge Base Presently Available to Do Ecosystem Management and to Assess Its Success.- 3.1 Overview.- 3.2 Factors Contributing to Ecosystem Scales.- 3.3 Spatial Boundary Considerations.- 3.4 Spatial Scales Overview.- 3.5 Disturbances as Temporal Agents of Ecosystem Change.- 3.6 Parameters Used to Study Ecosystems.- 4 Detecting Resistance and Resilience of Ecosystems.- 4.1 Signs of Ecosystem Degradation and Indicators of Ecosystem State Change.- 4.2 Useful Approaches for Detecting Ecosystem Change.- 5 Case Studies: Degrees of Ecosystem Management.- 5.1 Ecosystem Management: What Is Happening in the Field.- 5.2 Forest Ecosystem Management Assessment Team’s Management Plan for Old-Growth Ecosystems Within Range of the Northern Spotted Owl in the Pacific Northwest United States.- 5.3 National Forest Ecosystem Management.- 5.4 Developing Sustainable Management: Cases from the Pulp and Paper Companies.- 5.5 Adirondack Park Case Study.- 6 Science and Management of Ecosystems Synthesis.- 6.1 Ecosystem Management Framework.- 6.2 What Should Be Monitored for Ecosystem Management.- 6.3 Impediments to Utilizing the Ecosystem Management Approach.- 6.4 Adaptive Management.- 6.5 Principles of Ecosystem Management.- 6.6 Costs and Benefits of Instituting Ecosystem Management as a New Environmental Management Scheme.- References.- Appendix: Ecological, Management and Legal Development of Concepts Relevant to Ecosystems Through Time.