Typical vegetation dynamics and hydrological changes of Dongting Lake wetland from 1985 to 2020

Dongting Lake wetland provides important ecosystem functions for water regulation and biodiversity protection. However, the construction of the Three Gorges Dam has seriously affected the wetland hydrology and landscape. Therefore, it is of great significance to study the landscape dynamics of Dongting Lake wetland and its response to hydrological changes. Based on GEE cloud platform, this paper will obtain the long-term landscape dynamic changes of Dongting Lake wetland and analyze the influence of changes of multi-period water conditions on wetland landscape. The results show that, 1) From 1985 to 2020, the typical vegetation area of Dongting Lake wetland changed obviously on the whole lake scale. The evolution of wetland landscape pattern mainly occurred in East Dongting Lake, west of South Dongting Lake and north of West Dongting Lake. 2) According to the M-K method, the water level data of Dongting Lake showed a sudden change in 2003. This led to the decline of the annual water level of Dongting Lake and the decline of the water level during the wet season and retreating season. 3) The main hydrological variables affecting the change of the area of C. brevicuspis(Carex brevicuspis) and P. australis(Phragmites australis) in Dongting Lake wetland are the mean water level and minimum water level in wet season, and the mean water level, the minimum water level and the maximum water level in retreating season. This study can be used as a theoretical foundations to protect and restore the wetlands of Dongting Lake and manage the Three Gorges project.