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USING INFORMATION THEORY TO DEFINE A SUSTAINABILITY INDEX
Citation:
Fath*, B D., C. W. Pawlowski**, AND H C. Cabezas*. USING INFORMATION THEORY TO DEFINE A SUSTAINABILITY INDEX. Presented at Thid International Congress on Environmental Indices and Indicators, Rome, ITALY, October 03 - 05, 2001.
Impact/Purpose:
To inform the public.
Description:
Information theory has many applications in Ecology and Environmental science, such as a biodiversity indicator, as a measure of evolution, a measure of distance from thermodynamic equilibrium, and as a measure of system organization. Fisher Information, in particular, provides a powerful, underutilized methodology to measure the degree of system organization. Here, we use Fisher Information as a basis for a general theory and testable hypothesis of sustainability. The hypothesis states that Fisher Information is constant for sustainable systems. This information indicator is based on the probability of finding the system in a particular state, which is a surrogate for system stability. Tracking Fisher Information can indicate whether or not the system is becoming more or less stable because the smaller the phase space, which dynamical stable system oscillate through, the greater the information. Therefore, we propose two corollaries to interpret the direction of change of Fisher Information: Systems gaining Fisher information are sustainable, and systems logging Fisher Information are unsustainable. One issue in determining sustainability is the scale at which the information should be measured. We assume that sustainability depends on the stability of the systems functional groups and by aggregating functional groups we eliminate the individual dependence of the components on the Fischer Information. This hypothesis is demonstrated on a ten-compartment foodweb model with five functional groups: detritus, primary producers, herbivores, carnivores, and omnivores. This work, to identify suitable sustainability indicators using information theory, contributes to a larger multidisciplinary group at the USEPA's NRMRL.