passive-use value and total economic value of prominent biodiversity resources, CV and the value estimates that it generates will remain controversial.
- CV surveys of biodiversity or species-preservation issues often generate a relatively high proportion of protest or refusal responses, and some respondents indicate an unwillingness to address these issues in terms of trades for money. Good CV design—for example, structuring the CV as a referendum about spending more or less public money for preservation projects—can minimize the occurrence of protest or refusal responses. Nevertheless, some refuse to respond to even the best CV questions, and some of these nonrespondents are thoughtful people who draw on nonutilitarian moral philosophies when trying to resolve biodiversity issues. Chapter 4 makes clear that these are legitimate reactions, and they illustrate the limits of utilitarian CV in dealing with nonutilitarian concerns.
- CV comes in a variety of forms, each with its own communication and incentive properties, so blanket claims about the validity of CV are meaningless. But one constant is that the validity of any CV effort depends on respondents' understanding of what is being valued. In the case of biodiversity, citizen knowledge of the details of any particular case is likely to be quite low, so researchers will need to provide a good deal of case-specific information. Therefore, issues of communication and comprehension are likely to be prominent in criticism of many CV efforts directed at biodiversity. It is important to recognize that this problem applies also to any other approach or process that takes citizen opinion seriously.
Contingent-choice experiments are still in their infancy, especially in contexts where passive-use values can well dominate. Nevertheless, one might expect increasing application of these methods.
Various estimates have been made of the value of aspects of biodiversity. They include in this report the estimates for ecosystem services in chapter 3, the estimates in the Pacific Northwest forests and Grand Canyon flush case studies in this chapter. In addition, the article by Costanza and others (1977) discussed in a later section, A Tempest Over Valuing the World's Ecosystem Services, has global estimates of average per hectare and total values of biodiversity for 17 ecosystem services and 17 biomes.
In most of the cited examples, as well as in most of the numerous other published examples, the value estimates are for some particular element of biodiversity or for services that are related to some element of biodiversity. The estimates in the paper by Costanza and others (1997) are unusual in that the sum of the values for the 17 ecosystem services represents estimates of one-time annual values or the present value of the stream of expected future values.