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SUSTAINABLE SYSTEMS THEORY: ECOLOGICAL AND OTHER ASPECTS
Citation:
Pawlowski**, C. W., A Mayer**, T Hoagland*, AND H C. Cabezas*. SUSTAINABLE SYSTEMS THEORY: ECOLOGICAL AND OTHER ASPECTS. Presented at 5th Conference on Process Integration, Modeling and Optimization for Energy Saving and Pollution Reduction, Prague, Czech Republic, 8/25-29/2002.
Description:
While sustainability is generally associated with the definition given by the Brundtland Commission (World Commission on Environment and Development, 1987), namely development that "meets the needs and asperations of the present without compromising the ability to meet those of the future," it is important to recognize that a mathematical theory embodying these concepts would be immensely valuabe in humanity's efforts to manage the environment. The concept of sustainability applies to integrated systems comprosing humans and the rest of natue. The structures and operation of the human component (in tems of society, economy, law, etc.) must be such that these reinforce or promote the persistence of the structures and operation of the natural component (in terms of ecosystem trophic linkages, biodiversity, biotgeochemical cycles, etc.), and vice versa. Thus, one of the challenges of sustainability research lies in linking measures of ecosystem functioning to the structure and operation of the associated social system. We propose that indicators based on Information Theory can be used to develo measures that bridge the natural and human system elements, and make sense of the disparate state variables of the system. Thus, in this paper we examine the use of Fisher Information which is a statistical measure of variation based on the probability distribution function for the states of the system. We have developed a novel approach to using Fisher Information for dynamical systems, which, borrowing from statistical mechanics, uses an ensemble average of the system dynamics. We demonstrate this methodology using an uncalibrated 5-trophic level, 10-compartment (species) food web model with an associated basic social system for the population of omnibores at the top of the food chain. The model has five functional groups: detritus, primary producers, herbivores, carnivores, and omnivores. In addition to a seasonal forcing function, perturbation scenarios involving each of the parts of the system are simulated so as to explore the sustainability of the system under various types of stress. Since Fisher Information tracks the variation in a system, we hypothesize its use as an index of system sustainability. This work is part of a larger multidisciplinary group at the USEPA's NRMRL.