Integrating the economic valuation of ecosystem services for sustainable futures: methodological variability, scale effects, and policy implications

This study analyzed how valuation methods and spatial scale influence reported ecosystem service values. A systematic literature review following PRISMA guidelines and the PICO approach screened 222 articles from the Scopus database (2016–2025); after applying rigorous inclusion criteria, 38 studies were selected. Results reveal substantial methodological variability. Sum-based Total Economic Value (TEV) aggregation assigns 71.45% of total value to forests and vegetation; however, sensitivity analysis shows that this dominance is driven by a single macro-scale outlier. Median-based estimates are up to three orders of magnitude lower, indicating that robust central metrics are more appropriate than arithmetic sums for cross-study comparisons. Regulating services account for 19.47% of aggregated values, cultural services for 8.63%, and water resources for only 0.13% at local and regional scales. Cost-based methods yield the highest monetary estimates by capturing large-scale damage mitigation, whereas stated preference methods report substantially lower values ​​due to budget constraints. Regional estimates also vary by up to 23% because of differences in accessibility and beneficiary density. These findings have important policy implications. Ecosystem service valuations used in cost-benefit analyses, conservation prioritization, and environmental planning should avoid sum-based TEV aggregations because they can be dominated by extreme outliers and lead to biased resource allocation. Instead, policymakers should prioritize robust indicators such as medians and value ranges and explicitly account for spatial scale, beneficiary density, accessibility, and local socioeconomic conditions when evaluating green-blue infrastructure, ecosystem restoration, and conservation investments. Monetary valuation disparities reflect both methodological and contextual factors relevant to sustainable environmental decision-making.