Monitoring dynamic mangrove landscape patterns in China: Effects of natural and anthropogenic forcings during 1985–2020

Abstract

Many mangrove forests located along estuaries and deltas worldwide are currently facing irreparable losses caused by natural factors and intensive anthropogenic disturbances. The limited capabilities of traditional remote sensing processing platforms tend to lead to poor image processing consistency in medium- and large-scale areas, resulting in lower ground object classification accuracy. Consequently, little information is available regarding the extent and causes of variation in large-scale mangrove forests. In this study, we used Google Earth Engine mangrove forest data from eight periods between 1985 and 2020, with total accuracy rates of 82.95–90.15%, and combined landscape metrics with a centroid transfer model to quantitatively analyze the landscape evolution of mangrove forests in China. Finally, we employed a geodetector based on optimized parameters to quantitatively determine the potential mechanisms driving mangrove landscape evolution. Overall, a slight increase followed by a sharp decrease in mangrove forest area in China during the past 40 years, with a turning point around 2000 and substantial shifts in mangrove spatial patterns in Guangdong and Guangxi Provinces, particularly in the Pearl River Estuary and Beibu Gulf. The landscape pattern of Chinese mangrove forests has become fragmented and isolated through rapid urbanization in recent decades. Mangrove forests shifted significantly (> 31 km) early in the study period, followed by smaller shifts later in the study period. The optimal spatial scale of mangrove landscape driver detection was 270 m × 270 m. The variation in mangrove forest area was caused by the interactions of multiple factors, particularly between mean annual precipitation and other potential influencing factors. Government policies guided the conservation and management of mangrove forests in China to varying degrees throughout the study period. Our findings on the dynamics of mangrove forests provide a reference for integrated coastal management, which will contribute to the ecological utilization and high-quality development of coasts during extensive urbanization along the southeastern coast of China and similar large estuary deltas worldwide.