Abstract:

The effects of experimental warming and nitrogen addition on soil respiration were investigated using Li-8100 soil carbon flux measuring system in the desert steppe of Inner Mongolia. The results showed that infrared radiator raised soil temperature obviously in 2010 and 2011, and the temperature of 0~30 cm soil layer was 0.4~1.0℃ higher than control. The experimental warming didn't change the soil moisture significantly. Both nitrogen addition and warming didn't change soil respiration significantly. The rate of soil respiration had significant seasonal variation, ranging from 0.15 to 3.66μmol CO₂·m^-2·s^-1. There was strong correlation between soil respiration and precipitation, and between soil respiration and the moisture of 10 cm soil layer, the correlation coefficients were 0.67 and 0.70, respectively.There was strong water stress occurred in the desert steppe of Inner Mongolia, so soil moisture was the predominant factor of affecting soil respiration. Nitrogen addition had no obvious effect on soil respiration.

Key words: Soil respiration, Desert steppe, Experimental warming, Nitrogen addition, Water stress

摘要：

以内蒙古荒漠草原为研究对象,采用Li-8100土壤碳通量测量系统测定法,研究了控制性增温和氮素添加对荒漠草原土壤呼吸的影响.研究表明:红外辐射加热器在2年间显著提升了试验样地的土壤温度,0~30 cm土壤温度的增幅达0.4~1.0℃;但增温未能显著改变0~30 cm土壤湿度,也未能促进土壤呼吸;施氮、增温＋施氮的交互作用都未显著改变试验样地的土壤呼吸值.试验期间,土壤呼吸存在明显的季节变化,其变化幅度为0.15~3.66 μmol CO₂·m^-2·s^-1.土壤呼吸与降水量和10 cm土壤含水量存在较强的相关性,相关系数分别达0.67和0.70.内蒙古荒漠草原存在明显的水分胁迫,这使得土壤湿度取代土壤温度成为控制土壤碳通量的主要环境因子,而施加矿质氮肥对土壤呼吸的影响不显著.

关键词: 土壤呼吸, 荒漠草原, 模拟增温, 氮素添加, 水分胁迫