A comparative method for evaluating ecosystem services from the viewpoint of public works

Nature-based solutions (NbS), such as the implementation of environmental conservation and restoration as public works projects, require accurate and cost-effective assessments of the values related to the projects. The values should represent collective ecosystem services, individual services such as food provision and water purification, and other intangible services. To comprehensively assess such services, we proposed a novel method, which we call the comparative evaluation method. Our method is able to assess the value of each service category of an NbS project from a single questionnaire survey. Survey participants are asked to compare values of multiple services having anchoring prices. Our method determines the permissible economic value of environmental public works (PEP) in response to the quantity of service. The questionnaire results used for analysis are limited to those from respondents who made their PEP evaluation on the basis of their consideration of the appropriate expenditure of taxes. In addition, the method controls for the effect of the satisfaction that a person experiences from doing good deeds to reduce an overestimation of the values of services. Moreover, PEPs are not influenced by the respondent's annual income, age, sex, or educational background, and are based on personal values. Applying this new method, we surveyed residents of the watersheds of Tokyo Bay and Osaka Bay and evaluated nine ecosystem services. Overall, our new method is shown to be an effective method for evaluating the ecosystem services of NbS projects from the viewpoint of public works

Green port structures and their ecosystem services in highly urbanized Japanese bays

Green port structures (i.e. green infrastructure in ports and harbors) featuring habitats for marine organisms have been promoted in Japan as part of a comprehensive policy to reduce the environmental impact of ports and carry out habitat conservation, restoration, and creation. In this study, we evaluated the ecosystem services provided by green port structures in two highly urbanized bays (Tokyo Bay and Osaka Bay) in Japan. Our results show that the provision of some ecosystem services can be limited by circumstances particular to ports and other areas with restricted access. In the case of green port structures that have strong usage restrictions, for example, cultural services can only be provided if relevant authorities are prepared to conduct public events while ensuring participant safety. On the other hand, green port structures with weak usage restrictions are often equipped with incidental facilities such as parking lots and restrooms; these facilities can enhance the provision of cultural services (e.g. recreation and environmental education). Green port structures in highly urbanized bays often have usage restrictions, but their proximity to large populations means that they can potentially provide numerous ecosystem services. However, our study shows that appropriate management goals, such as protecting species and ensuring healthy habitats, are needed to maintain the value of these services in highly urbanized and eutrophic bays

Method for the quantitative evaluation of ecosystem services in coastal regions

Wetlands, tidal flats, seaweed beds, and coral reefs are valuable not only as habitats for many species, but also as places where people interact with the sea. Unfortunately, these areas have declined in recent years, so environmental improvement projects to conserve and restore them are being carried out across the world. In this study, we propose a method for quantifying ecosystem services, that is, useful for the proper maintenance and management of artificial tidal flats, a type of environmental improvement project. With this method, a conceptual model of the relationship between each service and related environmental factors in natural and social systems was created, and the relationships between services and environmental factors were clarified. The state of the environmental factors affecting each service was quantified, and the state of those factors was reflected in the evaluation value of the service. As a result, the method can identify which environmental factors need to be improved and if the goal is to increase the value of the targeted tidal flat. The method demonstrates an effective approach in environmental conservation for the restoration and preservation of coastal areas