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 ope rating at maximum power that can be quantified using validated Energy Syste ms models. The cumulative empower production (emergy) calculated using thes e models is proposed as a measure of ecological integrity. Ecological integ rity must be interpreted within the context of an ecosystem's position with in the relevant hierarchies of organization and cycles of change that contr ol system behavior. The local integrity and health of an ecosystem are norm ative concepts because they are evaluated relative to a standard or referen ce state. The underlying emergy signature responsible for generating ecosys tem organization provides an expectation for this reference state. Ecosyste ms also have global integrity, which is manifested as the flexibility to ma ximize 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 gen eral law that applies to all self-organizing systems on all scales, these d efinitions for ecological integrity and ecosystem health apply to both natu ral ecosystems and ecosystems dominated by human activities. Human-dominate d ecosystems with the highest integrity will be those in which the sum of t he empower produced by the economy and its supporting ecosystems is close t o a maximum.