全球气候变化下,极端干旱和强降水事件频发,土壤经历更为复杂和频繁的干湿交替过程,这对于土壤呼吸有极为重要的影响。以若尔盖高寒湿地土壤为研究对象,设置两种干湿交替强度(高强度和低强度)和两种干湿交替频率(高频率和低频率)以及恒定水分共5种处理,在人工气候箱恒温培养144 d,研究了干湿交替对若尔盖高寒湿地土壤呼吸、土壤可溶性碳、无机氮及其稳定性的影响。结果 表明:干湿交替强度对土壤呼吸、可溶性有机碳、可溶性有机碳/无机氮的比值及其稳定性影响显著,高强度干湿交替促进了呼吸,而低强度干湿交替有利于增加可溶性有机碳的含量和提高可溶性有机碳/无机氮的比值。铵态氮含量及铵态氮稳定性受干湿交替频率及交互作用的显著影响,硝态氮受干湿交替强度及交互作用的显著影响。无机氮及稳定性均不受干湿交替强度、频率及交互作用的影响。干湿交替强度和频率对若尔盖高寒湿地土壤呼吸、可溶性碳氮及其稳定性有不同程度的影响,这些结果有助于理解未来气候变化下高寒湿地碳循环过程及机制。
With the global climate change, extreme droughts and heavy precipitation events occur frequently, thus soils are undergoing more complicated and frequent drying-rewetting cycles, which have an important effect on soil respiration. We conducted a 144-day incubation experiment with two intensities(low and high intensities), two frequencies(low and high frequencies)of drying-rewetting cycles and one constant soil moisture to study the effect of drying-wetting intensity and frequency on soil respiration, soil dissolved organic carbon, inorganic nitrogen and their stability in Zoige alpine wetlands. The results showed that the intensity of drying-wetting cycles had significant effect on soil respiration, dissolved organic carbon, ratio of dissolved organic carbon to inorganic nitrogen and their stabilities; high-intensity drying-rewetting cycles promoted soil respiration, while low-intensity drying-rewetting cycles was beneficial to increase of the content of dissolved organic carbon and the ratio of dissolved organic carbon to inorganic nitrogen; the content and the stability of ammonium nitrogen were significantly affected by the frequency and interaction of drying-rewetting intensity and frequency, while nitrate nitrogen was significantly affected by the intensity and interaction of drying-rewetting intensity and frequency; inorganic nitrogen and its stability were not affected by the drying-rewetting cycles. In conclusion, the intensity and frequency of drying-rewetting cycles had different effects on the soil respiration, dissolved organic carbon, inorganic nitrogen and their stabilities in Zoige alpine wetlands. These results are helpful to understand the carbon cycle process and mechanism of alpine wetlands under future climate change.
