Economic valuation of ecosystem services and natural infrastructure: A quantitative review of the literature

Natural infrastructure is increasingly being recognized as a viable alternative or complement to traditional 'grey' infrastructure in addressing global infrastructural needs. From a policy design perspective, selecting the optimal strategy among alternatives requires complete knowledge of the costs and benefits associated with each option. Unlike traditional infrastructure, natural infrastructure delivers a host of ecosystem services that may be difficult to quantify and monetize. Markets do not exist for many of the ecosystem services associated with natural infrastructure, so monetizing the suite of benefits requires specialized techniques from the field of nonmarket valuation. In this paper we use bibliometric techniques to systematically review the literature on economic valuation of ecosystem services, natural infrastructure and, at their intersection, ecosystem services provided by natural infrastructure. With a combination of machine learning and keyword matching, we extract 6,796 relevant articles published between 1990 and 2023 from the Web of Science database. They reveal a dramatic increase in economic valuation studies -especially in the last fifteen years, with a prominent focus on recreation and tourism ecosystem services, marine infrastructure and stated preference valuation methods. We also identify knowledge gaps in terms of geographical coverage, ecosystem services, natural infrastructure, and valuation methods considered, and we provide suggestions for filling these gaps.