A Quantitative review of relationships between Ecosystem services

Abstract:

Each decision in natural resources management can generate trade-offs with respect to the provisioning of ecosystem services (ES). If the increase of one ES happens directly or indirectly at the cost of another ES, an attempt to maximize the provision of a single ES will lead to suboptimal results. However, decisions in natural resources management are often made without considering such trade-offs, despite their crucial role toward supporting better decision-making. The research on trade-offs between ES has gained some attention in the scientific community. However, a synthesis on existing knowledge and knowledge gaps is missing so far. We aim at closing that gap by a quantitative review of recent literature on trade-offs of ES. We looked at the pairs of ES that have been studied in ~100 case studies that report on trade-offs between ES. If a case study analyzed more than one ES pair, we looked at all pairwise combinations. We categorized relationships between these pairs of ES into the categories “trade-off”, ”synergy” or “no-effect”. Most pairs of ES had a clear association with one category: the majority of case studies that studied a specific pair of ES identified the same category of relationship between the two ES. Pairs of regulating services were typically synergetic in relationship, whereas provisioning services and regulating services typically showed a trade-off. However, for several pairs of ES we were not able to identify a dominate category of relationship. Our hypothesis is that this relates to either the scale of the analysis, the land system where the analysis took place or the method used to quantify the relationship. The number of case studies for each pair of ES was spread unevenly. This hinders the support for a conclusive statement drawn for the pairs. Our results showed further that the method used to identify the relationship between services had a strong effect on the direction of the effect. This suggests that researchers should consider their method carefully. We believe that our results are of use for the scientific community as well as for practitioners since they provide helpful information about which services to include in ES assessments. Furthermore, they allow a first check if critical trade-offs have been considered in an analysis.