A method for evaluating ecosystem services that can be used for the management of nature-based solution projects: A case study of Shiosai-Nagisa in Tokyo Bay

The major challenges in nature-based solution projects are evaluating the various ecosystem services and managing the projects in a sustainable manner while also considering various social issues. Here, we propose a method that can simultaneously evaluate multiple ecosystem services of nature-based solution projects (e.g., environmental improvement projects) and their sustainability, and we apply this method to Shiosai-Nagisa in Tokyo Bay. This method has three steps: (1) scoring each ecosystem service based on field data, (2) estimating the permissible economic value (i.e., the acceptable cost in monetary terms) of public works for each service in the reference value condition (service score = 100 points), and (3) calculating the economic value of each ecosystem service by using the service score and the permissible economic value of public works. Service scores are calculated from the present status and the likely near-term future status. This future status is obtained from a trend score and pressure and resilience scores, the latter of which represent environmental factors that can positively or negatively impact services. Since the service scores are related to environmental factors, the economic value obtained by this method is also related to environmental factors. Sustainability scores can also be evaluated using the likely near-term future status. As a test case, the method was applied to the management of an actual environmental improvement project. For ecosystem services with a negative sustainability score, we identified the environmental factors that contribute to negative sustainability and confirmed that improving those factors would improve the service index, sustainability score, and economic value. These results suggest that this method can be used to compare various project values and help project managers and stakeholders to better understand and visualize ecosystem services. • We propose a method to evaluate multiple ecosystem services simultaneously. • The method links the economic value of services and related environmental factors. • The method can be used to evaluate the sustainability of a project’s services. • Multiple services can be compared across projects and visualized. • The method is applicable to microscale nature-based solution projects.