Objective Mangroves are a crucial component of coastal carbon sinks, and the protection and restoration of mangrove wetlands serve as one of the effective approaches to mitigate global climate change. Investigating the spatiotemporal variation characteristics and driving factors of mangrove carbon storage in Hainan Island is of great significance for promoting the protection and sustainable development of mangrove wetlands.

Methods This study integrated the PLUS model and the InVEST model to analyze the spatial structure of land use and the characteristics of carbon storage changes in the major mangrove wetlands of Hainan Island over the past 20 years. On this basis, the spatiotemporal dynamics of land cover and carbon storage under three different development scenarios in 2030 were predicted and evaluated.

Results From 2000 to 2020, the mangrove cover area in the study area continued to increase, with an expansion of 1 329.84 hm². The area of other forest land (excluding mangroves) decreased continuously by 1 124.73 hm². Over the two decades, the carbon storage of mangroves and its proportion gradually increased. Although other forest lands also served as important carbon sink sources, their carbon storage showed a declining trend, and mangrove-covered areas were the most important carbon storage source within the wetlands. In the predictions under the three development scenarios in 2030, carbon storage under the natural development scenario was lower than that in 2020. In contrast, the total carbon storage under both the economic development and the ecological protection scenarios was higher than that in 2020, with the ecological protection scenario achieving the highest carbon storage. Driving factor analysis indicated that geofactors such as elevation, slope gradient, and slope aspect, as well as climatic factors including temperature and precipitation, had the most significant impacts on carbon storage values. The interactive and synergistic effects between economic factors (such as distance to government facilities and GDP) and natural factors were prominent.

Conclusions The proportion of mangroves in the wetland carbon storage of Hainan Island has shown a steady increasing trend. This result confirms the remarkable achievements made by Hainan province in mangrove wetland protection and the improvement of wetland carbon storage, and further reveals that ecological protection is the key pathway to optimizing carbon sink function. The findings of this study can provide important scientific support for the protection and restoration of mangrove wetlands in Hainan, the enhancement of coastal blue carbon sink potential, and the achievement of regional carbon neutrality goals.