氮添加对沙质草地土壤呼吸及其温度敏感性的影响

Effects of nitrogen addition on soil respiration and its temperature sensitivity in a sandy grassland

氮添加能改变土壤微生物代谢和植物根系活性,进而影响土壤呼吸过程。本文以科尔沁沙质草地为研究对象,探讨氮添加对土壤CO2排放的影响。结果表明:1)在观测期7—9月,土壤呼吸日动态呈不对称单峰曲线;氮添加对土壤呼吸日变化有显著影响(P<0.05),与对照(2.18μmol·m-2·s-1)相比,氮添加后土壤呼吸速率提高了15.2%;氮添加对昼间土壤呼吸的影响显著高于夜间(P<0.05),昼间和夜间土壤呼吸速率增幅分别为17.1%和14.4%。2)土壤呼吸月动态呈先升高后降低的趋势,7月18日达到最大值(3.36μmol·m-2·s-1);T检验结果表明,氮添加对7、8月土壤呼吸影响达到极显著水平(P<0.01),9月达到显著水平(P<0.05)。3)对照和氮添加的Q10值分别为3.27和3.30,R10值分别为0.42和0.54μmol·m-2·s-1,说明氮添加增强了沙质草地土壤呼吸对温度的敏感性。

Nitrogen（ N） addition can impact root activities and microbial metabolism,thus altering soil respiration rate. In this study we assessed the effects of N addition on soil CO2 flux in a Keerqin sandy grassland during July and September. The results showed that N addition significantly influenced the soil respiration rate. Compared with unfertilized plots（ 2.18 μmol·m-2·s-1）,the respiration rate of N-addition plots was increased by 15.2% and the increment of respiration rate in the daytime（ 17.1%） was higher than that at night（ 14. 4%）. N addition significantly increased soil respiration from July to September. The monthly variation in soil respiration firstly rose then declined,and peaked on the 18 th July（ 3.36 μmol·m-2·s-1）. N addition increased the temperature sensitivity of soil respiration and the basal soil respiration,with Q10 values as 3.27 and 3.30,and R10 values as 0.42 and 0.54 μmol·m-2·s-1in N-addition and unfertilized treatments,respectively.