Coastal wetland degradation and ecosystem service value change in the Yellow River Delta, China

The characteristics of changes in wetlands in different coastal areas vary, so it is necessary to select representative experimental areas to research wetland degradation, ecosystem service values (ESVs) and differences in changes among various wetland types in different ecological service function fields. The goal of this study is to better realize the spatiotemporal characteristics of wetland degradation and ESV in order to balance economic advancement and wetland ecological protection. The evolution of the wetland ESVs was analyzed by using the ESV equiv-alent correction technique and ecological contribution degree. The random forest (RF) classifi-cation model was utilized to extract wetland information in the Yellow River Delta (YRD) in four years (1990, 2000, 2010, and 2020). Thoroughly exploring the mechanism of impact and pro-posing reasonable suggestions based on a close combination of wetland changes and ecological services are conducive to the healthy development of global wetlands. The results demonstrated that the total area of wetlands expanded from 1459.5 km2 in 1990-1975.5 km2 in 2020, an in-crease of 28.5 %, with artificial wetlands increasing from 151.4 km2 to 1059.1 km2 and natural wetlands decreasing from 1308.1 km2 to 916.5 km2. The wetland ESV increased from 18.4 billion USD in 1990-28.6 billion USD in 2020. The transformation between types of natural wetlands tended to increase the ESV, while the transformation from natural wetlands to constructed wetlands reduced the ESV. The tidal flats and herbaceous wetlands have great value in terms of not only hydrological regulation but also gene diversity and climate regulation. The significant changes in various wetlands cause changes in different ecological service functions and promote changes in the ESV. Wetland protection, restoration, reconstruction, and rational utilization must be incorporated into urban land planning, and wetland parks and wetland protection zones should be established according to local conditions. This above research can provide typical examples and references for global wetland protection and sustainable development.