Abstract Changes in rainfall patterns can affect the soil nitrogen (N) cycles. Most studies have focused on the effect of the amount of rainfall, but the effect of the frequency of rainfall has rarely been considered. In this study, we conducted a field experiment in the Zoige alpine wetland that examined two levels of the amount of rainfall, i.e. 100% or 70% of the natural amounts of rainfall. In addition, we examined three frequencies of rainfall events. First was the natural interval, while the second and third were increases of 50% and 100% of the inter-rainfall dry periods based on the natural interval of the rainfall events, respectively. We found that the amount and frequency of rainfall had significant interactive effects on N mineralization, and thus influenced the concentration of mineral N in the Zoige alpine wetland. The reduction of the rainfall amount significantly increased N mineralization rate, NO3−-N concentration and mineral N stock in the high frequency treatment, and N mineralization rate, decreased them in the low frequency treatment. The variation of the soil NH4+-N, NO3−-N, and mineral N stock increased with the reduction in the rainfall frequency and the increase in the soil depth. Thus prolonged drought (low frequency of rainfall) and reduced rainfall due to future climatic change may decrease the mineral N concentration and N mineralization rate in Zoige alpine wetland, which may probably have a profound impact on the alpine wetland ecosystem.

中文翻译：

---

若尔盖高寒湿地降雨量和降雨频率对土壤氮矿化的影响

摘要 降雨模式的变化会影响土壤氮（N）循环。大多数研究都集中在降雨量的影响上，但很少考虑降雨频率的影响。在这项研究中，我们在若尔盖高山湿地进行了实地试验，考察了两个水平的降雨量，即 100% 或 70% 的自然降雨量。此外，我们检查了降雨事件的三种频率。第一个是自然间隔，而第二个和第三个是基于降雨事件的自然间隔分别增加了 50% 和 100% 的降雨间旱期。我们发现降雨的数量和频率对氮矿化具有显着的交互作用，从而影响若尔盖高寒湿地中矿质氮的浓度。降雨量的减少显着提高了高频处理的氮矿化率、NO3--N浓度和矿物氮储量，而低频处理的氮矿化率则降低。土壤NH4+-N、NO3--N和矿物N库的变化随着降雨频率的减少和土壤深度的增加而增加。因此，长期干旱（降雨频率低）和未来气候变化导致的降雨量减少可能会降低若尔盖高寒湿地的矿物质氮浓度和氮矿化率，这可能对高寒湿地生态系统产生深远的影响。在低频治疗中减少了它们。土壤NH4+-N、NO3--N和矿物N库的变化随着降雨频率的减少和土壤深度的增加而增加。因此，长期干旱（降雨频率低）和未来气候变化导致的降雨量减少可能会降低若尔盖高寒湿地的矿物质氮浓度和氮矿化率，这可能对高寒湿地生态系统产生深远的影响。在低频治疗中减少了它们。土壤NH4+-N、NO3--N和矿物N库的变化随着降雨频率的减少和土壤深度的增加而增加。因此，长期干旱（降雨频率低）和未来气候变化导致的降雨量减少可能会降低若尔盖高寒湿地的矿物质氮浓度和氮矿化率，这可能对高寒湿地生态系统产生深远的影响。