Wetlands are highly productive ecosystems, providing a number of functions (products and services) that are of value to people. The open-access nature and the public-good characteristics of wetlands often result in wetlands being undervalued in decisions relating to their use and conservation. There is now a substantial literature on wetland valuation, including two meta-analyses. These meta-analyses examine subsets of the available wetland valuation literature, focusing on temperate wetlands, a limited set of wetland functions, and a limited set of valuation techniques. We collect over 190 wetland valuation studies, providing 215 value observations, in order to present a more comprehensive meta-analysis of the valuation literature that includes tropical wetlands (e.g., mangroves), estimates from diverse valuation methodologies, and a broader range of wetland functions (e.g., biodiversity value).We also aim for a more comprehensive geographical coverage. We find that socioeconomic variables, such as income and population density, that are often omitted from such analyses are important in explaining wetland value. We also assess the prospects for using this analysis for out of sample value transfer, and find average transfer errors of 74%, with just under one-fifth of the transfers showing errors of 10% or less. This overall performance is, however, dominated to a considerable extent by transfer to small sites. The performance of value transfer for medium to large wetlands on average shows transfer errors smaller than 30%.
