A quantitative approach for offsetting the coastal reclamation impacts on multiple ecosystem services in the Yellow River Delta

Abstract

Reclamation of coastal wetlands causes the loss of multiple ecosystem services, necessitating that measures to address these impacts be taken. Offset ratios are commonly used to determine the extent of habitat areas that need to be restored elsewhere to achieve no net loss in wetlands; however, most calculation methods focus on individual impacts. In this study, a mathematical model accounting for multiple ecosystem services and their synergies or trade-offs relationships was developed to determine the required allocation of compensation area, and optimal amount of offsetting based on calculated ratios between damaged and compensated habitat areas. We took the Yellow River Delta in China as a case study, calculated the impacts on ecosystem services of different coastal reclamation types, and quantified the offset ratios for restoration based on different compensation scenarios accounting for time lags. We estimated that the offset ratios for the conversion of coastal wetlands into mariculture were smallest among all the reclamation types. We showed that compensating for carbon storage and water regulation with trade-offs will require higher offset ratios than those based on biodiversity only, and will also be more flexible. Our findings suggested that trade-offs and synergetic relationships should be prioritized when making decisions regarding the restoration of multiple ecosystem services. The findings presented herein will facilitate design of biodiversity offsets for coastal land reclamation based on their different impacts on ecosystem services. Overall, the results of this study have important implications for the ecological restoration and compensation of coastal wetlands in the face of coastal land reclamation.