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

The world’s forests, and the biodiversity that they contain, provide multiple cultural ecosystem services that are essential to people’s well-being. The last four decades have been characterised by huge societal, environmental, and technological change. Consequently, people’s preferences for, and values associated with, these services may have altered. To examine whether this is the case, we conducted a global meta-analysis, assessing 141 economic valuation studies. While contingent valuation studies revealed increasing values, travel cost studies indicated a decrease in values. In contrast, we observed no significant changes in choice experiment and hedonic pricing studies. These contrasting trends between different stated and revealed preference valuation methods indicate that there is no clear and consistent temporal pattern in the valuation of forest cultural ecosystem services over the last four decades. While a diversity of cultural ecosystem services and forest types were studied, we demonstrate that the existing evidence-base is biased towards high-income countries, and spiritual and symbolic interactions with forests remain understudied compared to recreational forest use. Large gaps in our knowledge geographically and across classes of cultural ecosystem services therefore limit our ability to fully quantify the monetary value of the world’s forests. The relative stability in values may stem from the interplay of contrasting societal, environmental, and technological changes. Despite the absence of a consistent pattern of change in the value people place on forests, we recommend to carefully consider temporal changes in values when undertaking benefit transfers. Our findings also highlight the importance of selecting payment vehicles in economic valuation studies that align with local socio-economic and cultural norms, particularly in low- and middle-income countries. Our findings may contribute to more contextually relevant and equitable approaches to managing forests, aligning policies with evolving societal and environmental dynamics.