Multi-Scale Temporal and Spatial Assessment of Coastal Wetland Ecosystem Health based on Three-Dimensional Model:An Empirical Study in Yancheng in Jiangsu Province

With the expansion of human activities and the aggravation of natural disturbances, coastal wetland ecosystems are seriously threatened by natural and anthropogenic disturbances, and it is of great significance to carry out coastal wetland ecosystem health assessment for the maintenance of coastal wetland ecosystems and the comprehensive management of coastal zones. Due to the complexity of influencing factors and obvious spatial heterogeneity, there is a great difficulty in evaluating the ecosystem health of coastal wetlands. In this study, based on remote sensing and field survey data, a coastal wetland ecosystem health (CWEH) model with three dimensions and characterized by spatial heterogeneity was established, covering indicators of external, internal and ecological elements, and focusing on the influence of spatial scale on the model, with the aim to establish a model that The CWEH model covers the indicators of external and internal elements and ecological elements, and pays attention to the influence of spatial scale on the model, in order to establish a coastal wetland ecosystem health model that involves all kinds of elements, takes into account the spatial heterogeneity, and has high applicability, and conducts empirical research with Yancheng coastal wetland in Jiangsu Province as the study area. The results showed that the CWEH results in the study area in 2020 were good and had obvious spatial heterogeneity, and the proportions of different CWEH status zones were ranked in descending order: the best (55.4%), the good (25.7%), the ordinary (17.1%), the poor (1.8%), and the worst (0). Among the four periods, the results of ecological health evaluation in the study area were 0.55, 0.54, 0.52 and 0.5 in 1992, 2000, 2012 and 2020, respectively, showing a continuous decreasing trend. Among them, there was a significant difference between CWEH inside and outside the nature reserve, and CWEH inside the reserve was significantly higher than outside. In the change of spatial scale from 100 m to 500 m, the CWEH of the whole study area gradually decreased, and the 100 m spatial scale was the most effective for the presentation of the study results and the characterization of spatial heterogeneity. In terms of influencing factors, human influence, landscape pattern and ecosystem productivity were the most important factors affecting CWEH. From 1992 to 2020, the increase in intensity of human activities and coastal erosion decreased CWEH, whereas the construction of coastal dykes and nature reserves improved CWEH in some areas. The influence of natural factors was weakening, and human activities became the main driving factor for spatial changes in CWEH. The influence of natural factors is decreasing, and human activities become the main driver of spatial changes of EWEH.