Ecosystem service indicators along the cascade: How do assessment and mapping studies position their indicators?

•We propose two meta-indicators for improving the consistency of ES assessment.•Their ‘position’ with respect to the ecosystem service cascade model.•Their position in geographical space, whether they are ‘anchored’ at supply or demand.•We found many ES can be characterized by reference to a specific cascade level.•Most studies also consistently ‘anchor’ their ES maps to the source ecosystems. As the mapping and assessment of ecosystem services (MAES) becomes a widely used tool in environmental governance, there is an increasing need for structure and standardization. In this study we present a systematic review of European MAES studies focussing on two important, but rarely documented aspects of ecosystem service (ES) indicators: (1) their ‘position’ with respect to the ecosystem service cascade model, and (2) their ‘position’ in geographical space, i.e. whether the maps are ‘anchored’ at the locations of their supply or their demand. From the 82 papers reviewed we found 427 ES indicators, which represented 33 ES. Among these indicators there were 108 (25%) that were mapped. ES are quite different in terms of their relationship with the main conceptual model of ES assessment studies. Most ES are typically measured at a specific point in the cascade, which is more or less the same across the different studies. While some ES (including most of the regulating ES, e.g. bio-remediation, hydrological cycle maintenance, or soil fertility) can clearly be linked to the ‘natural’ endpoint of the cascade, some others (including all cultural and some provisioning ES, like cultivated crops, or wild animals) are more frequently measured as actual flows or benefits delivered to humanity. There are few ES that are markedly heterogeneous in their cascade levels (e.g. water provision, pest control) for which apparently different assessment approaches exist. Considering spatial anchor, we have found that mapping at the source predominates in ES mapping studies: 91% of the mapped indicators are clearly linked to the source ecosystems. There were relatively few studies that applied a mixed approach, whereas indicators clearly anchored at beneficiaries were extremely rare. These two aspects of ES indicators discussed in this paper are critical in the successful operationalization and standardization of MAES assessments, which have been neglected in the MAES literature so far, which might be seen as key components in the future standardization of mapping and assessment approach