作者：Zhang, S., Zhong, H., Wang, B., Zou, F., Liu, Y., Nie, M. & Wu, L.

Wetlands constitute a major global carbon sink and play a pivotal role in climate change mitigation. While data syntheses, modeling studies, and manipulative experiments consistently show high variability in soil organic carbon (SOC) under changing hydrological regimes, long-term field-based evidence from natural wetlands is still lacking. Here, we conducted a decade-long in-situ observation in the Poyang Lake wetland, China, to assess the influence of hydrologic variability on SOC and to elucidate the underlying mechanisms. Results showed that hydrological conditions emerged as the key driver of SOC variation, accounting for 66.07% of the variance, compared with 19.46% explained by climate and 14.47% by soil properties. Hydrological regimes characterized by shortened flooding duration, increased water-level fluctuation, and drier soil conditions were associated with accelerated SOC loss. Structural equation modeling revealed that hydrological variability indirectly regulated SOC via plant-microbial pathways, with microbial carbon use efficiency and oxidase acting as important mediators. Moreover, SOC in mid-elevation wetlands proved vulnerable to changing hydrological conditions, highlighting an elevation-dependent response. Overall, these findings provide robust empirical evidence that hydrological variability is the dominant regulator of wetland SOC dynamics, offering critical insights for refining carbon-climate feedback predictions and informing hydrology-based wetland management strategies.

湿地是全球重要的碳汇，在减缓气候变化方面发挥着关键作用。尽管数据整合、模型研究和控制实验一致表明，在变化的水文情势下土壤有机碳具有高度变异性，但来自自然湿地的长期野外观测证据仍然缺乏。本研究在鄱阳湖湿地开展了长达十年的原位观测，以评估水文变异性对土壤有机碳的影响并阐明其潜在机制。结果表明，水文条件成为土壤有机碳变异的关键驱动因素，解释了66.07%的方差，而气候和土壤性质分别解释了19.46%和14.47%。以淹没历时缩短、水位波动加剧和土壤趋于干燥为特征的水文情势，与土壤有机碳加速流失密切相关。结构方程模型揭示，水文变异性通过植物-微生物途径间接调控土壤有机碳，其中微生物碳利用效率和氧化酶充当了重要的中介因子。此外，中海拔湿地的土壤有机碳更易受到变化水文条件的影响，凸显了海拔依赖性的响应特征。总体而言，这些发现提供了强有力的经验证据，证明水文变异性是湿地土壤有机碳动态的主导调节因子，为完善碳-气候反馈预测和制定基于水文的湿地管理策略提供了关键见解。

（来源：Journal of Hydrology 2026  DOI: 10.1016/j.jhydrol.2026.134919）