Validation of a rapid wetland ecosystem services assessment technique using the Delphi method
Damian Walters, Donovan C. Kotze, Alanna J. Rebelo, Lulu Pretorius, Nancy Job, Juliette V. Lagesse, Eddie Riddell, C. Cowden
Abstract
Wetlands differ in their ability to provide ecosystem services, and thus there is a need to assess ecosystem service delivery in order to prioritize protection and restoration efforts. We used a Delphi-based expert-panel method to validate an ecosystem services assessment technique in a context where there is a paucity of field-level process-based research into the delivery of ecosystem services. The validation process entailed comparing scores from a panel of wetland experts to that derived by WET-EcoServices. Three wetlands were selected where detailed information relating to the supply of regulating services was available. At each site a selection of regulating services was assessed and then scored using the technique and independently by the panel of experts. The expert panel reached high levels of consensus (83%) on the scores for the three case studies used in the validation process. The consensus formed a useful basis for the validation of the technique. Statistical testing revealed no significant differences between expert and technique scores however, when considered practically, there were small differences in 53% of the scores, moderate differences in 23% and large in 20%. In most cases the technique over scored relative to the expert assessment. The results were useful for identifying specific refinements to the technique. The study demonstrates how a three-way “engagement” of a rapid-assessment technique, expert opinion and detailed research can be used to improve ecosystem services assessments in resource-limited situations. We reflected on the use of the Delphi method in a resource-constrained environment and advocate its careful application in similar contexts.