中文摘要：

短期的氧化氩氮(N2O ) 脉搏排出物为年度 N2O 排出物的可观的部分由降水报道引起了并且被土壤氮(N) 动力学极大地影响。在中国半干旱的适度的大草原，然而，到降水和土壤 N 可获得性的联合变化的 N2O 排出物的反应充分还没被理解。在这研究，我们在内部蒙古的一个半干旱的适度的典型大草原进行了二个7天的地实验，中国，搏动调查 N2O 排放源于人工的 降水事件(近似等价于 10.0 公里降雨)不到四个 N 增加层次( 0 ， 5 ， 10 ，并且 20 g N/( m2 攠業獳潩獮琠?牰'虨宫摤嫕?異獬獥甠摮牥搠晩敦敲瑮渠瑩潲敧?癡楡慬楢楬楴獥椠??敳業牡摩琠浥数慲整猠整灰?景?湮牥?湯潧楬??楨慮

英文摘要：

Short-term nitrous oxide（N2O） pulse emissions caused by precipitation account for a considerable portion of the annual N2O emissions and are greatly influenced by soil nitrogen（N） dynamics. However, in Chinese semiarid temperate steppes, the response of N2O emissions to the coupling changes of precipitation and soil N availability is not yet fully understood. In this study, we conducted two 7-day field experiments in a semiarid temperate typical steppe of Inner Mongolia, China, to investigate the N2O emission pulses resulting from artificial precipitation events（approximately equivalent to 10.0 mm rainfall） under four N addition levels（0, 5, 10 and 20 g N/（m2·a）） using the static opaque chamber technique. The results show that the simulated rainfall during the dry period in 2010 caused greater short-term emission bursts than that during the relatively rainy observation period in 2011（P〈0.05）. No significant increase was observed for either the N2O peak effluxes or the weekly cumulative emissions（P〉0.05） with single water addition. The peak values of N2O efflux increased with the increasing N input. Only the treatments with water and medium（WN10） or high N addition（WN20） significantly increased the cumulative N2O emissions（P〈0.01） in both experimental periods. Under drought condition, the variations in soil N2O effluxes were positively correlated with the soil NH4-N concentrations in the three N input treatments（WN5, WN10, and WN20）. Besides, the soil moisture and temperature also greatly influenced the N2O pulse emissions, particularly the N2O pulse under the relatively rainy soil condition or in the treatments without N addition（ZN and ZWN）. The responses of the plant metabolism to the varying precipitation distribution and the length of drought period prior to rainfall could greatly affect the soil N dynamics and N2O emission pulses in semiarid grasslands.