A New Ecology presents an ecosystem theory based on the following ecosystem properties: physical openness, ontic openness, directionality, connectivity, a complex dynamic for growth and development, and a complex dynamic response to disturbances. Each of these properties is developed in detail to show that these basic and characteristic properties can be applied to explain a wide spectrum of ecological obsevations and convections. It is also shown that the properties have application for environmental management and for assessment of ecosystem health.* Demonstrates an ecosystem theory that can be applied to explain ecological observations and rules* Presents an ecosystem theory based upon a systems approach* Discusses an ecosystem theory that is based on a few basic properties that are characteristic for ecosystmes