Quantifying temporal changes in the monetary value of forest cultural ecosystem services globally: a meta-analysis

The world’s forests, and the biodiversity they contain, provide multiple cultural ecosystem services that are essential to people’s well-being. However, interactions between people and forests evolve alongside broader societal and environmental change, raising questions about whether the values associated with forest cultural ecosystem services have shifted over time. To examine this, we conducted a global meta-analysis of 137 economic valuation studies comprising 705 observations gathered over the four decades between 1980 and 2019. Our results did not provide evidence of statistically significant temporal trends for travel cost, contingent valuation, choice experiment, or hedonic pricing estimates. Likewise, a recreation-only subsample did not provide evidence of a statistically significant temporal trend in monetary values over time. Although a diversity of cultural ecosystem service classes and forest types were examined, the existing evidence base is biased towards high-income countries, and valuation studies remain heavily concentrated on recreational interactions with forests, while spiritual and symbolic interactions are rarely quantified. Such gaps in our knowledge limit our ability to quantify the monetary value of forest cultural ecosystem services globally. Although we did not find evidence of temporal trends in the value people place on forest cultural ecosystem services, the substantial heterogeneity and method-specific patterns observed in our models suggest that temporal stability should not be assumed when undertaking benefit transfers. Given these findings, methodological heterogeneity and contextual differences should be considered when applying benefit transfer methods in environmental decision-making. The scarcity of studies in low- and middle-income countries, combined with a strong focus on recreation, underscores the need for broader and geographically diverse valuation research. Addressing these gaps may support more context-sensitive approaches to forest management and conservation.