At its most basic level, the valuation of ecosystem services consists of nothing more than measuring multiple services in terms of a common unit that serves as a measure of the desirability of that service to people. Because of their convenience and wide applicability, monetary (i.e. currency) units are commonly used. However, non-monetary value units can also be used (Farber et al. 2006). For example, we developed a composite service index for Hubbard Brook that was calculated as a average of multiple ecosystem service metrics multiplied by value weights. Using a questionnaire (Figure 1), we surveyed people living and working in the region to estimate these value weights. Using the same methodology, we created a similar visualization for Turkey Lakes; in this case, users of the visualization must provide the value weights.
Ecosystem services are usually valued using monetary values. Where markets exist for ecosystem services and products (e.g. timber, carbon markets, wetland banks, etc.), values can be inferred from prices. Markets do not exist for most ecosystem services, however, so ecological economists rely on a number of methods to estimate economic values (Farber et al. 2006). These include revealed-preference methods (e.g. travel costs, hedonic pricing), stated-preference methods (e.g. contingent valuation, conjoint valuation), and cost-based approaches (e.g. replacement costs). In FEST, we rely primarily on benefit transfer to attach economic value to services; benefit transfer consists of identifying existing value estimates and applying them to new case studies, where the two systems are sufficiently similar in both ecological and social terms. Case studies which include monetary valuation include recreational fishing and forest ecosystem services in the Adirondacks.