Biophysical Measures to Support Analysis and Communication of Existence Values.

A recent focus of ecosystem services research has been on the definition of biophysical outcomes and measures most closely linked to social welfare. There is a particular need to identify biophysical outcomes corresponding to existence values. (Values associated with existence apart from any current or future use). We review economic and ecological evidence to answer two key questions: First, what are ideal characteristics of linking indicators for existence values? Linking indicators should be: understandable, subject to direct sensory perception, represented at relevant temporal and spatial scales, comprehensive, and quantifiable in a repeatable manner. Second, what types of ecosystem outcomes are most likely to be associated with these values? We distinguish between indicators of taxa and ecological landscapes, and then multiple subcategories within each. Our fundamental conclusion is that while there are general principles informing the specification of linking indicators of existence values, there is no compact set of indicators or measures that applies universally. The case-specific nature of these issues-general guidelines notwithstanding-implies the need for sustained partnerships between social and biophysical scientists to address questions of indicator choice.