International Journal of Marine Science, 2025, Vol.15, No.4, 220-232 http://www.aquapublisher.com/index.php/ijms 221 also export part of organic carbon to offshore deposits through tides, thereby expanding the scope of their carbon sink influence. This unique “blue carbon” function makes mangroves play an indispensable role in the global carbon cycle (Cuenca-Ocay, 2024). However, man-made interference and changes in the natural environment are putting mangrove ecosystems at serious threats. Since the mid-20th century, the global mangrove area has been greatly reduced due to factors such as coastal development, aquaculture, and timber harvesting. It is estimated that 30%~50% have been lost, and the resulting carbon emissions and ecological function degradation are worrying. In recent years, countries have gradually realized the importance of mangrove protection and restoration to carbon sinks and incorporated them into national strategies for mitigating and adapting to climate change (Ferreira and Lacerda, 2022). In this context, systematically studying the ecological basis of mangrove carbon sink function, identifying the causes of its decline in carbon sink function, and exploring effective recovery and management strategies are of great practical significance for improving mangrove carbon sink and serving the "dual carbon" goal. This article aims to review and analyze various strategies and practical experiences in enhancing carbon sinks through mangrove restoration and management, in order to provide scientific reference for coastal ecological protection and climate change response. 2 Ecological Basis of Mangrove Carbon Sink Function 2.1 Mangrove biomass and soil carbon storage mechanism The reason why mangroves are known as an efficient carbon sink system is due to its unique biomass distribution and soil carbon burial mechanism. On the one hand, mangrove plants have developed root systems and high growth volumes, and can still accumulate a large amount of biomass in harsh intertidal environments. Mangroves are rich in carbon in their trunks, branches, leaves and roots, and their biomass per unit area is often higher than that of land forests of the same latitude. More importantly, the mangrove ecosystem distributes a considerable proportion of fixed carbon underground: a large number of pillar roots and lateral roots that support trees are deeply rooted in the mud, and carbon is continuously input into the soil (Zhang et al., 2022). With the fall of organic debris such as mangrove leaves and branches, these organic matter decomposes extremely slowly in long-term flooding and hypoxic peat environments, and gradually accumulates to form a thick carbon-rich deposit layer (Perera and Amarasinghe, 2021). This "underground carbon pump" mechanism makes mangrove soil a huge carbon reservoir, accounting for more than half of the total carbon reserves of mangrove ecosystems. Research shows that in mangrove peat soil, carbon can be stably buried for hundreds to thousands of years. Once mangroves are damaged, these carbons that were originally in the soil will be reexposed and released into the atmosphere in the form of CO₂ (Salmo et al., 2019). Therefore, maintaining the accumulation of mangrove biomass and sequestration of soil carbon is crucial to its carbon sink function. 2.2 Regional differences in mangrove carbon sink capacity The carbon sink capacity of mangroves varies significantly in different regions, and is affected by multiple factors such as climatic conditions, species composition and geographical environment. Mangroves in tropical regions (such as Southeast Asia) usually have the highest carbon storage and carbon sequestration rate due to their high temperature and high humidity throughout the year (Adame et al., 2020). Some studies compared the carbon storage of mangrove ecosystems on different continents and found that the total ecosystem carbon storage per hectare of mangroves in Southeast Asia and Oceania often exceeded 800~1 000 tons, while the carbon storage per hectare of mangroves in arid areas such as the Middle East may be less than 200 tons per hectare (Chatting et al., 2020). On the one hand, this difference is attributed to the tall and dense trees in tropical mangroves and deep soil deposits, which can accumulate more biomass and peat carbon; on the other hand, regional tidal and sedimentary environments also play a role. For example, in large deltas or estuaries, mangroves often benefit from adequate freshwater and sediment supply, and are more efficient in burying carbon. In contrast, mangroves in subtropical and temperate marginal areas have slower plant growth, short and sparse forests, and relatively low carbon sink capacity. In addition, the dominant tree species and community structure of mangroves in different regions will
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