Mapping Ecosystem Services’ Values: Current Practice and Future Prospects

摘要

Mapping of ecosystem services’ (ESS) values means valuing ESS in monetary terms across a relatively large geographical area and including the examination of how values vary across space. Thereby, mapping of ESS values reveals additional information as compared to traditional site-specific ESS valuation, which is beneficial for designing efficient land use policies for maintaining biodiversity and ESS supply. One of the first studies mapping ESS is the well-known article by Costanza et al. (1997), who mapped global ESS values. This paper raised a lot of attention and initiated a debate on value mapping in general and on the meaningfulness of aggregate global values. Since then, the number of publications mapping ESS values has grown exponentially, with almost 60% being published after 2007. Until now, no comprehensive review of the relevant literature has been conducted and no consensus exists on what method is best for a specific purpose. Within this paper, we analyse all peer reviewed journal articles published before 2012 that map ESS values and we review them according to the methodologies used for ESS quantification and valuation, the ESS assessed, study rational and case study area characteristics. Our findings show that methodologies, in particular how spatial variations of ESS values are estimated, and also their spatial scope, rational and ESS focus differ widely. Still, most case studies rely on relatively simplistic approaches using land use/cover data as a proxy for ESS supply and its values. However, a tendency exists towards more sophisticated methodologies using ESS models and value functions, which integrate a variety of spatial variables and which are validated against primary data. Accuracy and precision of ESS value maps is an important but insufficiently addressed issue. Only a minor part of all studies quantify potential error margins of mapped values and more than 40% do not address the issue of accuracy at all. However, existing evidence indicates that error margins can be high. Based on our findings, we identify current practices and developments in the mapping of EES values and provide guidelines and recommendations for future applications and research.