Valuing ecosystem services on the basis of service-providing units: A promising solution to the 'endpoint problem' in stated preference methods

Standardized methods are required to measure ecosystem services in order to value them. In this paper, we argue that the service-providing unit (SPU) concept may help achieve this objective by promoting the systematic quantification of the key components of nature that provide services (e.g., population density of a key pollinator) and linking these with measurable outcomes for human well-being. We discuss and provide examples of the potential role of the SPU concept in improving economic valuation of ecosystem services. Further, we suggest the concept may contribute to addressing the endpoint problem, which can be defined simply as the inability of researchers to communicate the implications of environmental change in a way that is understood by a broad cross-section of society. The endpoint problem is of particular relevance to stated preference approaches, and we discuss the capacity of the SPU concept to refine these approaches. We argue that the concept enhances interdisciplinary collaboration, promoting more validated, well-informed valuation applications. It also has the potential to minimize 'warm glow effects' and put the notion of marginal changes in the provision of ecosystem services in a new light.