In recent years, an increasing number of ecosystems are threatened by seasonal flooding, changing non‐flooded shoreland (NF) into seasonally flooded wetland (SF), but the consequences of this hydrological change for soil organic carbon (SOC) dynamics remain unknown. In this study, we investigated how the SOC content was determined by flooding duration and soil physicochemical variables in adjacent SF and NF at six depths (0–10 cm, 10–20 cm, 20–30 cm, 30–50 cm, 50–70 cm, and 70–100 cm) at Shengjin Lake in subtropical China. Soil physicochemistry and SOC composition were analyzed, and Fourier‐transformed infrared spectroscopy (FTIR) was used to resolve the SOC composition. Neither SOC content nor the vertical distribution of SOC was distinguishable between the sites. However, FTIR data revealed that plant‐originated aliphatics and amides were higher at NF than SF sites, with the opposite pattern for aromatics. At SF sites, SOC content was positively affected by soil moisture and flooding duration and was negatively impacted by soil particle size at most soil layers. At NF sites, SOC content was mainly affected by silt and total Fe at the top 20 cm soil, while a higher fraction of plant‐derived labile C was positively correlated to SOC contents at 30–100 cm depth. The results hence indicated a strong effect of seasonal flooding on SOC dynamics in terrestrial ecosystems. SOC stabilization induced by low mineralization and high adsorption played a central role at SF sites, while SOC formation through plant input was more important at NF sites. Our findings suggest that management strategies designed to conserve SOC will need to be site‐specific.

中文翻译：

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土壤有机碳储量对亚热带季节性洪水湿地和非洪水滨地森林的物理化学特征的影响不同


近年来，越来越多的生态系统受到季节性洪水的威胁，将非洪水泛滥的海岸地 （NF） 转变为季节性洪水湿地 （SF），但这种水文变化对土壤有机碳 （SOC） 动态的影响仍然未知。本研究以亚热带盛津湖为研究对象，研究了亚热带盛津湖6个深度（0—10—20 cm、20—30 cm、30—50 cm、50—70 cm和70—100 cm）相邻SF和NF的淹水和土壤理化变量如何测定土壤有机碳含量。分析土壤物理化学和 SOC 组成，并使用傅里叶变换红外光谱 （FTIR） 解析 SOC 组成。站点之间的 SOC 含量和 SOC 的垂直分布均无法区分。然而，FTIR 数据显示，植物来源的脂肪族和酰胺在 NF 位点高于 SF 位点，芳烃的模式相反。在 SF 站点，土壤水分和洪水持续时间对 SOC 含量产生正影响，而大多数土壤层的土壤粒径对土壤颗粒尺寸产生负影响。在 NF 站点，SOC 含量主要受顶部 20 cm 土壤的淤泥和总铁的影响，而较高比例的植物来源不稳定 C 与 30-100 cm 深度的 SOC 含量呈正相关。因此，结果表明季节性洪水对陆地生态系统的 SOC 动态有很强的影响。低矿化和高吸附诱导的 SOC 稳定在 SF 站点起着核心作用，而通过植物输入形成的 SOC 在 NF 站点更为重要。我们的研究结果表明，旨在保护 SOC 的管理策略需要针对特定地点。