Contributions of plant- and microbial-derived residuals to mangrove soil carbon stocks: Implications for blue carbon sequestration

Coastal blue carbon ecosystems, particularly mangroves, are becoming increasingly recognised for their importance in mitigating climate change. Still, the specific patterns and drivers of plant lignin components and microbial necromass accumulation in these ecosystems are unclear.In response, we carried out a study along a 40-year mangrove restoration chronosequence, measuring lignin phenol and amino sugar concentrations in soil profiles (0-100 cm) as indicators of plant-based and microbial-derived residues, respectively.Our results showed that restoration significantly increased plant lignin phenol and amino sugar concentrations, with mature mangroves having much higher concentrations than tidal flats. During restoration, the fungal necromass was greater than the bacterial necromass. The factors influencing the lignin phenols were tree biomass, total nitrogen, pH and salinity, while those influencing the formation of amino sugars were total biomass, soil C: N ratio and pH. While the amino sugars decreased, the lignin phenols increased with the content of SOC, providing evidence of the important role lignin phenol components play in the formation of SOC in mangrove.Synthesis: By separating soil carbon into plant-based and microbial-derived components, our results demonstrate that the carbon stock in mangrove sediments is vulnerable to disturbances and that changes from anaerobic to aerobic conditions cause significant carbon mineralisation. The precise identification of soil carbon sources in blue carbon ecosystems could aid in elucidating the mechanisms of soil carbon sequestration and their responses to environmental changes.Read the free Plain Language Summary for this article on the Journal blog. 滨湿?红树?缓气.植微残壤?红树恢晰.酚氨糖植微?红树恢壤贡offspring.?红树恢著壤酚氨糖?菌残累著菌.酚树,壤氮,pH 盐?壤微,壤氮pH 氨糖offspring.?红树恢?植占呈趋?微呈趋.壤植微?红树壤?壤厌氧氧换固红树壤.?蓝壤壤固. Read the free Plain Language Summary for this article on the Journal blog.image