Abstract: Coastal wetland resources are abundant in Jiangsu Province. The area of salt marsh has declined since the 1980s, due to human activities (such as reclamation) and the invasion of alien species. Based on Landsat remote sensing images and the application of Digital Shoreline Analysis System (DSAS), we examined the variations of the reclamation area and salt marsh vegetation area in the tidal flat vegetation zone of coastal wetlands in Jiangsu Province from 1985 to 2020, the relationships between their changes, as well as the vegetation effects of reclamation scale. The results showed that: (1) From 1985 to 2020, the vegetation zone shifted seawards significantly, spatially corresponding an increase of reclamation area. The change hotspot area gradually moved southward, from Sheyang EstuaryBeiling Estuary in 1985 to Liangtuo EstuaryYaowang Port after 2015. (2) The areas of salt marshes and reclamation varied greatly among different bank sections. The ratio of reclamation area to salt marshes increased rapidly, increasing from 0.017∶1 in 1985 to 5.59∶1 in 2020. The reclamation area was significantly negatively correlated with the salt marsh area. (3) With the gradual decline of the salt marsh vegetation zone, the correlation between the area of salt marshes and the extension rate of tidal flat vegetation shifted from significant positive to non-significant, indicating that the scale of salt marsh vegetation area played a certain role in promoting tidal flat vegetation zone extending to the sea.

Key words: coastal wetland, tidal flat vegetation, salt marsh, reclamation area, Spartina alterniflora.