Abstract: Mangrove wetlands, located in the intertidal zone of the tropics and subtropics, are one of the extremely important coastal ecosystems, which are of great value in typhoon resistance, coastal seawall protection and carbon sequestration. However, complex couplings between land and sea forcings have caused a large-scale loss of mangrove forests worldwidely. Understanding the dynamic changes of mangrove wetlands is crucial for furtherly realization of their losses and causes, which can provide necessary support for the better restoration of the destructive mangrove forest. Based on the Google Earth Engine platform, the spatial and temporal dynamic information of mangrove wetlands was extracted over the MaolingJiang Estuary of Beibu Gulf between 1992-2021, and then mangrove dynamic changes and associated impacted factors were analyzed. The results showed that: (1) As of 2021, the tidal flats at the Maolingjiang estuary contain 707.76 hm2 of mangrove with Aegiceras corniculatum as the building species. Mangroves are mainly distributed in the Dalidun Bund and Tuanhe Island Tail tidal flats, with the least distribution in the Liangwu Bund near the southern side of the main stream. (2) From 1992 to 2021, the tidal flat at the Maolingjiang estuary experienced a change process of "increase - decrease - increase", and the mangrove area maintained an increasing trend. (3) High-intensity human activities are the main driving force of mangrove dynamic change in the Maolingjiang estuary. The promulgation of policies and regulations ensures the sustainable development of the regional mangrove tidal flats, and the channel-tidal water dynamics directly drive the development of the tidal flats and mangroves to the sea. The study of mangrove dynamic changes in the tidal flats at the Maolingjiang estuary is of guiding significance to the location of mangrove plantations and the formulation of mangrove protection policies.

Key words: Mangrove Forest Margin Line, Tidal Flat, Maolingjiang Estuary, Google Earth Engine