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FISHER INFORMATION OF DYNAMIC REGIME TRANSITIONS IN ECOLOGICAL SYSTEMS
Mayer**, A, C. W. Pawlowski**, AND H C. Cabezas*. FISHER INFORMATION OF DYNAMIC REGIME TRANSITIONS IN ECOLOGICAL SYSTEMS. 2002 AIChE Conference, Session T2001: Sustainability in Chemical Engineering, Indianapolis, IN, 11/05/2002.
Ecosystems often exhibit transitions between multiple dynamic regimes (or steady states). As ecosystems experience perturbations of varying regularity and intensity, they may either remain within the state space neighborhood of the current regime, or ?flip? into the neighborhood of a regime with different characteristics. An increasingly integral aspect of many ecological, economic, and social decisions is their impact on the sustainability of particular dynamic regimes of ecosystems. Sustainability entails a human preference for one particular regime versus another, and the persistence of that regime with regard to the human and natural perturbations exacted on the system. Information theory has significantly advanced our ability to quantify the organizational complexity inherent in systems despite imperfect observations or ?signals? from the source system. Fisher Information is one of several measures developed under the theme of estimation theory, and may be a useful measure to identify the degree to which a system is at risk of ?flipping? into a different dynamic regime. We developed a Fisher Information index for dynamic systems in a periodic steady state and applied it to a simple, two species Lotka-Volterra predator-prey model. Changes in the carrying capacity (size) of the system resulted in different stable steady states establishing themselves, each with a characteristic Fisher Information. Transitions or ?flips? between steady states were identified with changes in Fisher Information. We then examined data collected from the global climate system, and identified steady-state regimes and transitions, despite significant noise in the data. If transition phases between regimes can be detected early enough, human activity suspected of contributing to regime changes can be altered.