Assessing the impacts of reclamation and invasion on ecological dynamics of coastal wetland vegetation in the Yangtze Estuary from 1985 to 2019:A case study of Chongming Island, China

The distribution of coastal wetland vegetation is influenced by biological invasions, human reclamations and climate changes, which continually reshape vegetation structures. However, limited attention has been given to the impact of biological invasion on native vegetation and tidal wetlands. This study focuses on the wetlands of Chongming Island, employing a multi-feature dataset combining spectral, phenological, and temporal information on the Google Earth Engine (GEE) platform. Using the Random Forest (RF) classification method, we analyzed annual vegetation distribution changes and examined the distinct effects of natural and anthropogenic factors. The research results indicate that: (1) From 1985 to 2019, the total area of Chongming Island expanded, while wetland vegetation decreased due to embankment construction and island connection projects. (2) The total area of wetland vegetation on Chongming Island dropped to its lowest point in 2002 (3812.76 ha), and then gradually recovered. (3) Human reclamation was the primary driver of vegetation changes from 1985 to 1995. (4) Vegetation distribution in Dongtan was influenced by both human and natural factors, whereas Beiliuyao affected by the invasion and expansion of the S. alterniflor. These findings provide valuable insights into the drivers of long-term vegetation distribution changes, offering essential data and theoretical support for sustainable development and management of Chongming Island's ecosystems.