水分和氮素添加对内蒙古半干旱温带生态系统蒸发散的影响

Effects of water and nitrogen addition on ecosystem evapotranspiration in semi-arid temperate grassland of Inner Mongolia

[目的]未来降水格局变化和氮沉降增加将会不同程度的影响生态系统蒸发散,然而生态系统蒸发散是如何响应降雪、降雨和氮沉降增加的尚有待于进一步研究。[方法]本研究采用野外控制试验,利用在内蒙古半干旱温带草地已建立的春季增雪、夏季增雨和氮素添加平台,对生态系统蒸发散的变化情况进行动态监测。[结果]研究结果显示,水分添加在2011年和2013年提高生态系统蒸发散和土壤含水量,但显著降低土壤温度;在2012年提高土壤含水量,显著降低土壤温度,但对生态系统蒸发散作用不显著。氮素添加在2012年显著降低土壤含水量,在2013年显著降低土壤温度,在其他年份对土壤含水量、土壤温度和生态系统蒸发散影响均不显著。另外,研究发现水分和氮素添加对生态系统蒸发散、土壤含水量和土壤温度的影响不存在交互作用。[结论]水分添加和氮素添加主要通过改变土壤含水量和土壤温度,从而影响生态系统蒸发散,同时受降水、光合有效辐射和大气温度的影响。

[Objective]The change in precipitation pattern and the increase in nitrogen deposition in the future will affect the ecosystem evapotranspiration,but how the ecosystem evapotranspiration responds to the increase in snow,rainfall and nitrogen deposition needs to be further studied.[Methods]In this study,a field manipulated experiment was conducted to dynamically monitor the change of the ecosystem evapotranspiration in the spring snow addition,summer water addition and nitrogen addition platforms in a semi-arid temperate grassland of Inner Mongolia.[Results]The results showed that water addition increased ecosystem evaporation and soil moisture,but significantly reduced soil temperature in 2011 and 2013.In 2012,water addition increased the soil moisture but decreased soil temperature,and had no effect on ecosystem evapotranspiration.Nitrogen addition significantly reduced soil water in 2012 and soil temperature in 2013,but had no significant effect on soil moisture,soil temperature and ecosystem evapotranspiration in other years.In addition,it was found that there were no interactions between the effects of water and nitrogen addition on ecosystem evapotranspiration,soil moisture and soil temperature.[Conclusion]Water and nitrogen addition affects the ecosystem evapotranspiration mainly by changing soil moisture and soil temperature,and are also affected by precipitation,photosynthetically effective radiation and atmospheric temperature.