Using energy systems theory to define, measure, and interpret ecological integrity and ecosystem health

Energy systems theory provides a theoretical basis for defining, measuring, and interpreting the concepts of ecological integrity and ecosystem health. Ecological integrity is defined as an emergent property of ecosystems operating at maximum power that can be quantified using validated Energy Systems models. The cumulative empower production (emergy) calculated using these models is proposed as a measure of ecological integrity. Ecological integrity must be interpreted within the context of an ecosystem's position within the relevant hierarchies of organization and cycles of change that control system behavior. The local integrity and health of an ecosystem are normative concepts because they are evaluated relative to a standard or reference state. The underlying emergy signature responsible for generating ecosystem organization provides an expectation for this reference state. Ecosystems also have global integrity, which is manifested as the flexibility to maximize empower over time in the face of changing external forcing functions. Global integrity has no fixed reference but can be evaluated by comparing alternative system designs. Because the maximum empower principle is a general law that applies to all self-organizing systems on all scales, these definitions for ecological integrity and ecosystem health apply to both natural ecosystems and ecosystems dominated by human activities. Human-dominated ecosystems with the highest integrity will be those in which the sum of the empower produced by the economy and its supporting ecosystems is close to a maximum.