Dynamic monitoring and driving force analysis of salt marsh vegetation distribution in Yancheng Nature Reserve

To investigate the spatial and temporal evolution of salt marsh vegetation in Jiangsu Yancheng Wetland Rare Bird National Nature Reserve, a phenological feature composite method was used to invert the area of four types of salt marsh vegetation (Spartina alterniflora, Phragmites australis, Suaeda salsa and Imperata cylindrica) in the core area of the Reserve from 1984-2021, and to analyze its spatial and temporal evolution and driving mechanism. The results showed that the total area of salt marsh vegetation in the core area increased from 11113.2 hm² to 16528.14 hm², with a compound annual growth rate of 1.11%, mainly due to the ability of Spartina alterniflora to preserve the beach and promote siltation. Spartina alterniflora and Phragmites australis, by occupying a large number of Suaeda salsa beach, Phragmites australis beach and light beach, the area increased by 4968.62 hm² and 8806.95 hm², with compound annual growth rates of 26.67% and 6.88%, respectively. The areas of Suaeda salsa and Imperata cylindrica decreased by 3494.25 hm² and 4867.38hm² respectively by the superimposed effects of natural factors such as ecological niche competition and artificial disturbances such as aquaculture bases, with a compound annual growth rate of -3.14% and -8.11%, resulting in the severe fragmentation of the suitable habitats.