摘要:氮矿化是湿地生态系统养分循环的重要组成部分，氮输入及温度变化对土壤氮矿化的影响具有复杂性。为了探究湿地土壤氮矿化特征对温度及氮输入的响应，选择黄河入海口北部滨岸高潮滩的碱蓬湿地为研究对象，基于野外原位氮负荷增强模拟试验（N0：0 g N m^-2 a^-1；N1：9.0 g N m^-2 a^-1；N2：12.0 g N m^-2 a^-1；N3：18.0 g N m^-2 a^-1），于生长季末获取不同氮处理下的土壤（S-N0、S-N1、S-N2和S-N3）开展室内培养实验。结果表明，不同氮处理土壤的氮累积矿化量均呈现出培养初期（0-14 d）增加迅速，培养中期（14-42 d）骤然降低，而培养后期（42-84 d）趋于稳定的变化特征，其值整体表现为S-N3 > S-N0 > S-N2 > S-N1（P > 0.05）。培养后期，不同氮处理土壤的累积矿化量在20℃和25℃下的差异均达到极显著或显著水平（P < 0.01或P < 0.05），且S-N2在此间的矿化能力最强。氮输入整体降低了土壤氮矿化对温度的敏感性（Q₁₀），其中S-N2土壤的温度敏感性最低，更利于持续供氮。不同氮处理土壤的氮矿化速率和累积矿化量与培养温度、土壤基质质量密切相关，且在一定范围内较高的温度和较低的C/N有利于氮矿化的进行。研究发现，未来黄河口氮负荷增强以及温度持续上升背景下，碱蓬湿地土壤氮养分及温度条件改变将会影响其供氮能力，适量氮输入（N2）将有利于土壤保持持续稳定的供氮能力。



Abstract:Nitrogen (N) mineralization is an important component of nutrient cycling in wetland ecosystems, and effects of nitrogen input and temperature change on nitrogen mineralization of soils are complex. To explore the effects of temperature and N import on N mineralization characteristics of soils with different N treatments, the topsoil (0-10 cm) with different substrate qualities (S-N0, S-N1, S-N2 and S-N3) were sampled at the end of the growing season from different N input plots (N0: 0 g N m^-2 a^-1; N1: 9.0 g N m^-2 a^-1; N2: 12.0 g N m^-2 a^-1; N3: 18.0 g N m^-2 a^-1) in Suaeda salsa marsh of the Yellow River estuary, and the incubation experiment was carried out. Results showed that, under different incubation temperatures, the cumulative mineralized N of the four soils increased rapidly at initial stage (0-14 days), after that decreased suddenly at middle stage (14-42 days), then tended toward stability at final stage (42-84 days), and the values in incubation period generally showed S-N3 > S-N0 > S-N2 > S-N1 (P > 0.05). At the end of incubation experiment, the cumulativly mineralized N of the four soils were significantly different at 20 ℃ and 25 ℃ (P < 0.01 or P < 0.05), and S-N2 showed the strongest mineralization ability. N input generally decreased the sensitivity of N mineralization to temperature (Q₁₀), thereinto. S-N2 showed the lowest Q₁₀ and it was more favorable for continuous N supply. The mineralization rates and cumulative mineralization N of the four soils were closely related to incubation temperatures and substrate qualities of soils, while within a certain range, higher temperatures and lower C/N were more favorable for the process of N mineralization. This study found that, as N loading and temperature in the Yellow River estuary increased continuously in future, the alterations of soil N nutrient and temperature would greatly affect the N supply capacity of S. salsa soils, and the soils with N2 input would maintain sustainable and stable N supply capacity.





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