Economic valuation of ecosystem services in agriculture and agroforestry: A meta-analysis

The economic valuation of ecosystem services in agriculture and agroforestry is crucial for sustainable development. However, valuation methods vary significantly across contexts. Using the PRISMA framework, we systematically reviewed 146 studies, combined effect sizes through meta-analytic modeling, and conducted spatial autocorrelation analyses to explore geographic patterns. Market price valuation (MPV) and contingent valuation (CVM) are the most used methods in ecosystem service assessments, accounting for 25.8% and 20.8% of studies, respectively. The CVM and life cycle impact assessment (LCIA) approaches play a key role in interdisciplinary research, connecting all ecosystem service categories. Analysis revealed extreme heterogeneity and significant publication bias for cultural (CULT), provisioning (PROV), and regulating (REG) services. Valuation outcomes are strongly influenced by the choice of methods (such as MPV and benefit transfer methods) and unit standardization practices, with effect sizes decreasing when values are standardized to United States dollars per ha per year (USD/ha/year). Spatial autocorrelation was minimal, indicating the importance of local context in the valuation results. Temporal trends indicate episodic changes in the relative effectiveness of valuation approaches. Empirically, MPV showed greater robustness (18%) than CVM, which exhibited greater sensitivity to data constraints (16%). These findings highlight the need to prioritize data quality and context specificity within standardized valuation frameworks to improve policy relevance and comparability in ecosystem service assessments, particularly for underrepresented CULT and supporting (SUP) services.