施氮对克氏针茅草原土壤呼吸的影响

发布时间：2018-02-20 05:54

本文关键词： 氮沉降克氏针茅草原土壤呼吸太仆寺旗　出处：《内蒙古师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,由于内蒙古地区采矿业及发电业迅速发展,氮沉降量逐年增多。为研究氮沉降对内蒙古克氏针茅(Stipa krylovii)草原土壤呼吸的影响,于2014年7月开始在内蒙古太仆寺旗的克氏针茅草原开展了模拟氮沉降的控制实验,设置对照(N0)和5个模拟氮沉降(NO3-)处理,分别为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)和50 g N m-2·yr-1(N5)监测不同氮沉降处理下土壤呼吸季节变化和日动态变化,并结合土壤表层水热条件分析该地区的土壤呼吸特性,探讨不同施氮水平对草地CO2排放的影响,为未来全球变化下的天然草地保护与管理提供科学依据和理论支撑。主要结论如下:(1)各处理下的土壤呼吸速率为夏季秋季冬季。重复测量方差结果表明,与对照组比,施氮改变了土壤呼吸日均和白天的季节动态变化。而各施氮水平下的黑夜土壤呼吸季节动态变化与对照组的无差异。克氏针茅草原昼夜土壤呼吸速率最大值2.45±0.36μmol·m-2·s-1出现在7月份,最小值0.11±0.01μmol·m-2·s-1出现在11月。(2)7月和9月不同施氮水平之间的日均、白天、黑夜土壤呼吸的整体趋势为随着施氮量的增加,土壤呼吸减弱,即施氮抑制了土壤呼吸。11月的昼夜和白天土壤呼吸则无显著变化,而11月黑夜的土壤呼吸随着施氮量的增加逐渐增长,施氮促进了黑夜的土壤呼吸。从土壤呼吸日变化曲线图可得知,施氮没有改变土壤呼吸日变化规律。(3)采用线性回归模型得出,土壤温度、湿度、施氮、地下生物量和C/N共同解释了克氏针茅草原土壤呼吸速率季节变化的74.7%,拟合结果优于以温度为参数的线性回归模型(72.2%)。而土壤湿度、地下生物量以及施氮与土壤呼吸相关性不显著。影响土壤呼吸速率的主导因子是温度,土壤呼吸与土壤温度之间存在极显著的指数关系。虽然以相关性分析法得出的结论为施氮并未改变土壤呼吸温度敏感性,但对比同一月份的不同水平下的Q10值,受施氮影响Q10逐渐降低。(4)适量的氮素会增加地下生物量,而高氮则抑制其生长。国家自然科学基金资助项目(41371069)(5)土壤C/N比随着施氮量的增加而变化。与对照组相比,各土层土壤C/N比随着施氮量的增加而增加。而施氮量达到N3水平时土壤碳氮比随着施氮量的增加而逐渐下降。本研究中,施氮抑制了土壤呼吸:低氮增加了地下生物量和C/N。高氮减少了地下生物量,降低了土壤C/N。从观测结果来看,同一水平的施氮量对土壤根系呼吸和土壤微生物呼吸具有不同的影响。
[Abstract]:In recent years, because of the rapid development of mining industry and power generation industry in Inner Mongolia, the amount of nitrogen deposition increased year by year. In order to study the effect of nitrogen deposition on soil respiration of Stipa krylovii steppe in Inner Mongolia, In July 2014, the control experiment of simulated nitrogen deposition was carried out in the Plantago krshinshinensis in Taibusi Banner, Inner Mongolia, with the control of N _ 0) and five simulated nitrogen deposition no _ 3) treatments. The seasonal and diurnal changes of soil respiration under different nitrogen deposition treatments were monitored, and the soil respiration characteristics in this area were analyzed by means of 10 g N m-2 路yr-1 N _ 2 路yr ~ (-1) N _ (2) N _ (m ~ (-2) 路yr ~ (-1) N ~ (-1)) and 50 g N ~ (m ~ (-2) 路yr-1 ~ (-1) N _ (5)) respectively. The effects of different nitrogen levels on CO2 emission from grassland were studied. The main conclusions are as follows: the soil respiration rate of each treatment is summer, autumn and winter. The results of repeated measurement variance show that, compared with the control group, the soil respiration rate of each treatment is in summer, autumn and winter. The daily and daytime seasonal dynamic changes of soil respiration were changed by nitrogen application, but there was no difference between the night soil respiration season and the control group. The maximum diurnal soil respiration rate appeared in July, and the maximum soil respiration rate was 2.45 卤0.36 渭 mol 路m ~ (-2) 路s ~ (-1) on July. The minimum value of 0. 11 卤0. 01 渭 mol 路m -2 路s -1 appeared in November. Soil respiration was inhibited by nitrogen application, but no significant change was observed during the day and night of November, but the soil respiration increased gradually with the increase of nitrogen application rate in November. From the curve of diurnal variation of soil respiration, nitrogen application did not change the diurnal variation of soil respiration. The below-ground biomass and C / N explained the seasonal variation of soil respiration rate of Neymphus krjabini. The fitting results were better than that of the linear regression model with temperature as the parameter (72.2%), and the soil moisture was higher than that of the linear regression model (72.2%). There was no significant correlation between underground biomass and nitrogen application and soil respiration. Temperature was the main factor affecting soil respiration rate. There was a significant exponential relationship between soil respiration and soil temperature. Although the conclusion of correlation analysis was that nitrogen application did not change the sensitivity of soil respiration temperature, the Q10 values at different levels were compared with those of January. The effect of nitrogen application on Q10 decreased gradually. (4) proper amount of nitrogen increased the underground biomass, but high nitrogen inhibited the growth. The C / N ratio of soil changed with the increase of N application rate, compared with the control group, supported by the National Natural Science Foundation of China (NSF-funded project No. 41371069). The C / N ratio of different soil layers increased with the increase of N application rate, and the C / N ratio decreased with the increase of N application rate when the N application rate reached N 3 level. Nitrogen application inhibited soil respiration: low nitrogen increased underground biomass and C / N. High nitrogen reduced underground biomass, decreased soil C / N. Nitrogen application at the same level had different effects on soil root respiration and soil microbial respiration.
【学位授予单位】：内蒙古师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S812.2

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