Exploring soil carbon drivers across natural mangroves, restored mangroves, and tidal flats: Implications for subtropical coastal carbon management

Abstract

Despite extensive mangrove restoration efforts globally and evidence highlighting the importance of allochthonous carbon in soil organic carbon (SOC) storage, the overall impacts of restoration on SOC storage and its ecological drivers remain unclear. Our study addresses these gaps by analyzing SOC dynamics and their drivers across multiple soil depths in natural mangroves, restored mangroves, and tidal flats within subtropical coastal ecosystems. Our results showed that natural mangroves had the highest SOC levels, particularly in surface soils, confirming their higher carbon sequestration potential. Restored mangroves exhibited incomplete SOC recovery, with levels closer to tidal flats than to natural mangroves. Tidal flats displayed minimal SOC storage, with little variation across soil depths. Surface soils were identified as the primary carbon storage zone in all ecosystems. Distinct drivers of SOC were identified for three different types of ecosystems: species composition, total nitrogen (TN), total phosphorus (TP), and salinity in natural mangroves; species composition and TN in restored mangroves; and TN and TP in tidal flats. Our findings underscore the need for nutrient and salinity management in mangrove restoration and the inclusion of tidal flats in regional carbon strategies, offering valuable insights for advancing restoration practices and achieving global carbon neutrality goals.