Analysis of spatiotemporal evolution characteristics and recovery patterns of mangrove forests in China since 1978

Mangrove ecosystems have garnered significant attention for their pivotal role in the global carbon cycle and their contributions to multiple UN Sustainable Development Goals. In China, the strategic pivot towards comprehensive ecological restoration in mangrove management underscores an urgent need for a nuanced understanding of mangrove evolutionary patterns. However, existing remote sensing-based information on mangrove dynamics exhibits discrepancies, lacking a cohesive and precise understanding. Accordingly, this study utilized high-resolution GaoFen imagery and precise visual interpretation methods to meticulously update an existing mangrove dataset through 2022, ensuring high accuracy and improved timeliness. Building on this, the study conducted a rigorous spatiotemporal analysis of mangrove dynamics from 1978 to 2022, developed an index to assess recovery status, and ultimately proposed targeted recommendations for conservation and restoration. Findings reveal that between 2018 and 2022, China's mangrove expanse witnessed an average annual net increase of 2.82%, marking an unprecedented high. Breaking down the net change, the rate of gain accelerated, averaging 878.63 ha per year, but it is noteworthy that the losses also increased rapidly, tripling that of the previous period, mainly in regions with intense human activities such as the Pearl River Estuary. This finding complements the general perception of a continuous net increase in mangrove areas, highlighting the paradox of significant contraction occurring alongside rapid expansion. Additionally, by 2022, mangrove extent had recovered to 28,641 ha, essentially returning to the 1978 level, yet characterized by poor stability and significant spatial heterogeneity, with Guangdong and Hainan exhibiting recovery indices below the average. The study emphasizes that the ecosystem's intrinsic restorative capabilities have emerged as a critical factor in offsetting losses and signaling a positive trend. The latest data provided by this study can offer actionable insights and support for mangrove conservation and restoration initiatives, serving the goal of ecosystem recovery and affirming their indispensable role in environmental governance.