cautionary principle, and the safe minimum standard. In responding to uncertainty, it is important to recognize the possibility of learning over time and the potential value of flexibility, but not to let incomplete information bias environmental policy decisions in favor of the status quo.
The preceding synthesis of the report’s major conclusions regarding ecosystem valuation suggests that a number of issues or factors enter into the appropriate design of a study of the value of a change in aquatic ecosystem services. The context of the study and the way in which the resulting values will be used play a key role in determining the type of value estimate that is needed. In addition, the type of information that is required to answer the valuation question and the amount of information that is available about key economic and ecological relationships are important considerations. This strongly suggests that the valuation exercise will be very context specific and that a single, “one-size-fitsall” or “cookbook” approach cannot be used. Instead, the resource manager or decision-maker who is conducting a study or evaluating the results of a valuation study should assess how well the study is designed in the context of the specific problem it seeks to address. The following is a checklist to aid in that assessment. It identifies questions that should be discussed openly (and in some cases debated) and satisfactorily resolved in the course of the valuation exercise.
What is the purpose of the valuation exercise?
What is the policy decision to be made?
What decision criteria will be used and what role will the results of the valuation exercise play?
How will the valuation results be used?
What information is needed to answer the policy question?
What is the scope of the valuation exercise?
What ecosystem services will be valued?
Is it necessary to value only one or a few ecosystem services, or is it necessary to value all services?
What is the appropriate geographic scale of the valuation exercise?
Is it a local, regional, or national analysis?
What is the relevant population to include in the value estimates (i.e., whose values to include)?
How is the valuation question framed?