论文部分内容阅读
土壤呼吸是全球碳循环的一个重要组成部分、土壤碳库的主要输出途径和大气CO2重要的源。利用FACE(free-air CO2 enrichment)技术平台,采用LI6400红外气体分析仪(IRGA)-田间原位测定的方法,研究了大气CO2浓度升高和不同氮肥水平对水稻/小麦轮作制中冬小麦生长期间土壤呼吸的影响。结果表明,在整个测定期间,CO2浓度升高均增强了土壤呼吸的排放速率和释放量,增幅随着氮肥施用量的增加而增大,土壤呼吸在孕穗-抽穗期达到最大值。土壤呼吸同土壤温度呈极显著的指数相关;随施氮量从112.5kg·hm-2增加到2255kg·hm-2,FACE处理的Q10值从2.98增大为3.26,但比相应的Ambient(对照浓度)处理的Q10值下降了6.3%和18.3%,显然CO2浓度升高降低了土壤呼吸对温度增加的敏感性。总之,大气CO2浓度升高将加快土壤向大气的CO2排放,将有助于评价未来高CO2浓度环境对农田生态系统土壤碳循环的影响。
Soil respiration is an important part of the global carbon cycle, the main source of soil carbon pool and an important source of atmospheric CO2. Using the free-air CO2 enrichment (FACE) technology platform, the LI6400 infrared gas analyzer (IRGA) was used to determine the effects of elevated atmospheric CO2 concentration and different nitrogen levels on the growth of winter wheat during the rotation of rice and wheat. Effects of soil respiration. The results showed that during the whole measurement period, the increase of CO2 concentration enhanced the respiration rate and release rate of soil respiration, the increase rate increased with the increase of nitrogen application rate, and the soil respiration reached the maximum at booting-heading stage. Soil respiration had a very significant exponential correlation with soil temperature. With the increase of N application rate from 112.5kg · hm-2 to 2255kg · hm-2, the Q10 value of FACE treatment increased from 2.98 to 3.26, Concentration) decreased by 6.3% and 18.3%, respectively. Obviously, the increase of CO2 concentration reduced the sensitivity of soil respiration to temperature increase. In conclusion, the increase of atmospheric CO2 concentration will accelerate the CO2 emission from the soil to the atmosphere, which will help evaluate the impact of the future high CO2 concentration on soil carbon cycling in farmland ecosystems.