| In recent years, due to mining and power generation industry rapidly develop in Inner Mongolia, nitrogen deposition volume increased year by year. For the study on the influence of nitrogen deposition in Inner Mongolia’s Stipa krylovii grassland soil respiration, fromthe July 2014, we begun to do the simulated nitrogen deposition experiment in Inner Mongolia taibus banner,set the CK(N0) and five nitrogen rates of simulated nitrogen deposition: 2 g N m-2?yr-1(N1)、5 g N m-2?yr-1(N2)、10 g N m-2?yr-1(N3)、25 g N m-2?yr-1(N4)and 50 g N m-2?yr-1(N5), Monitoring season change and dynamic change of soil respiration under different nitrogen deposition processing, and combining the soil hydrothermal condition analysis of soil respiration characteristics, discusses the influence of different nitrogen levels on the grass CO2 flux, In order to provide a scientific basis and theoretical support for the future of natural grasslandprotection and management under global change. The results showed:(1) soil respiration with different fertilizations are summer > autumn > winter. Repeated measurement results show that compare with CK, nitrogen changed seasonal dynamic of soil respiration during daily and day. And the night soil respiration under different N application levels, seasonal dynamic changes are no difference with the CK. Survey the soil resperition of day and night, the maximum value is 2.45± 0.36ìmol·m-2·s-1in July, the minimum value is 0.11±0.01ìmol·m-2·s-1in November(2) compare with July to September different nitrogen level of the average daily, day and night soil repiration, the trend of soil respiration is with the increase of N application, soil respiration isGradually weakened. In November,soil respiration is no significant changes during the daily and day.But night soil respiration is gradually increased with the increase of N application.from the change curve of soil respiration under different experimental treatment,we can find that N application did not change regulation of soil respiration.(3) using multivariable linear regression model, the temperature, humidity, nitrogen, underground biomass and C/N was explain the the seasonal variation of soil respiration rate 74.7%, the fitting result is better than that of temperature as the parameter of the linear regression model(72.2%). And soil moisture, underground biomass and nitrogen and no significant correlation between soil respiration. The dominant factor of soil respiration rate is temperature, soil respiration and soil temperature significantly between index. Although the conclusion by correlation analysis method for nitrogen did not change the temperature sensitivity of soil respiration, but contrast Q10 values under different levels of the same month, affected by nitrogen Q10 gradually reduced.(4) the amount of nitrogen can increase the underground biomass, while high nitrogen inhibits the growth of underground biomass.(5) the soil C/N ratio increased with the increase of N application rate changes. Compared with the control group, the soil layer soil C/N ratio increased with the increase of N application rate increased. The n application at N3 level of soil carbon and nitrogen ratio increased with the increase of n application rate gradually decreases.In this study, nitrogen inhibits soil respiration, low nitrogen increased underground biomass and C/N. High nitrogen reduced the underground biomass, decreased soil C/N. From the point of observation, the same level of N application have different effects on soil root respiration and soil microbial respiration. |
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