Expert Mental Models of Ecosystem Risk. W.G.B. (Bill) Smith, Eco-Risk Research Unit, Institute for Resources and the Environment, University of British Columbia, Vancouver, CANADA and Economic and Regulatory Affairs, Policy and Communications, 16 PVM Environment Canada, Ottawa, CANADA K1A OH3, fax-telephone 01-613-233-5992, e-mail WGB.Smith@EC.GC.CA
An ecosystem perspective is appealing to policy makers who want a multi-issue, place-based approach to decision making. Before we can think and act in terms of ecosystems, we must reconsider the role of expert risk perception and judgement in ecological risk assessment. While the language of ecology has captured the public’s imagination, it has failed to become the language of public policy because ecologists do not share a common view of the functioning of nature or the role of humans in it. Experts play a leading role in defining the criteria by which risks are evaluated. In this role, their personal values and priorities often come into play (Lackey 1997, Menzie-Cura 1996). Their values and beliefs are expressed through the use of metaphors (Rapoport 1993) and mental models of risk (Bostrom 1996, Carley & Palmquist 1992).
Mental models of risk are not solely matters of individual cognition (Slovic et al 1997) but also correspond to worldviews, deeply held beliefs and values about society, its functioning, and potential fate (Kempton et al. 1995, Dake 1991.) Three generic worldviews have been identified that may partly explain why experts have different mental models of ecosystem risk (Slovic & Peters 1998, Dake 1992, Thompson et al. 1990). A careful review has also shown that three mental models of ecosystem risk dominate the research literature. The carrying capacity model is based on the assumption that experts can determine the maximum rate of resource consumption or waste discharge that an ecosystem can absorb (e.g. Rees 1995, Holling 1992, Orians 1990). The biological integrity model focuses on conserving natural self-regenerating communities of species characteristic of an ecosystem (e.g. Angermeir & Karr 1994, Woodley et al. 1993). The ecosystem health model attempts to link a critical set of ecosystem functions and services to our health and well being (e.g. CCME 1996, EC 1993, Costanza et al 1992.)
Entity-attribute or repertory grid methodologies are being used to elicit and compare expert’s mental models of ecosystem risk. Shaw and Gaines (RepGrid Manual 1993) have developed online techniques and algorithms to map and display the elements, attributes, and values that characterise ecosystems, and to clarify the underlying distinctions. For the ecosystem approach to become a reality, it will be necessary to reconcile conflicting mental models of ecological risk to build a consensus about a new paradigm, one that could help policy makers evaluate future choices.
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