Land Use and Ecological Risk Changes in Typical Bays Around the South China Sea

To promote the comprehensive and sustainable development of bay areas, it is necessary to conduct in-depth research on the land use and ecological risk of bays in different geographical locations. Based on the Landsat series of images, this study used the random forest classification method to extract the land use information of Manila Bay, Kuching Bay and the Bay of Bangkok in South China Sea for four periods from 1990 to 2020 and analyzed the changes in land use, dynamics and structure. The landscape sensitivity index is built to optimize the ecological risk assessment model to complete the ecological risk assessment. The results showed that the main land use types of the three bays were forestland and cultivated land (paddy field and dry field), and there were large differences in the change trends. The overall change of secondary forest in Manila Bay is the strongest, the change of artificial forest in Kuching Bay is the strongest, and the change of dry field in the Bay of Bangkok is the strongest. The Bay of Bangkok has the highest degree of land use, while Kuching Bay has a relatively low degree of land use, reflects that the impact of human activities varies significantly among different bays. The overall ecological risk of the three bays showed a trend of decreasing first and then increasing, with an overall upward trend. Manila Bay has the highest ecological risk due to the high landscape vulnerability and significant topographical undulations of its natural forests and secondary forests, followed by that in Kuching Bay due to the highly fragmented landscape caused by urbanization, and the ecological risk in the Bay of Bangkok was relatively low due to being dominated by highly vulnerable dry fields. It is necessary to protect natural forests and mangroves, avoid the development of natural shorelines, and take into account the layout of ecological scenes in the development of construction land and cultivated land. This study contributes to a deeper understanding of the development status of coastal areas around the South China Sea and provides support for the planning and management of land use in the bay.