Abstract
In this paper, an indicator is defined as some feature of a system that reveals its condition or state. This implies that there is a normal state or multiple states of the system. The presence or absence of an indicator or change in the value of an indicator discloses that the system has deviated from its normal state or that it has changed states, if it has multiple states. For an indicator to be useful, it must be responsive, easy to detect, and specific. An indicator that points to the reason that a system has deviated from its normal state or is in its current state is more useful than a more general indicator that reveals little or nothing about the system other than it has changed.
Prepared for the International Symposium on Biological Indicators, October 15–19, 1990, Ft. Lauderdale, FL.
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© 1992 Springer Science+Business Media Dordrecht
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van der Valk, A.G., Squires, L. (1992). Indicators of Flooding Derived from Aerial Photography in Northern Prairie Wetlands. In: McKenzie, D.H., Hyatt, D.E., McDonald, V.J. (eds) Ecological Indicators. Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-4659-7_33
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