奇台县强碱土土壤呼吸日和季节变化研究

发布时间：2018-02-23 22:12

本文关键词： 强碱土土壤呼吸变化特征影响因子降水　出处：《新疆大学》2015年硕士论文　论文类型：学位论文

【摘要】：干旱半干旱地区的土壤无机碳的储量巨大,它对于整个区域乃至全球碳循环的作用不可忽视。本研究采用LI-8100开路式土壤碳通量测量仪测定了无植被生长、有机质含量极少的强碱土土壤呼吸。野外采取土柱并灭菌处理,通过比较其无机与有机土壤呼吸所占比例,确定强碱土土壤呼吸的主导方式。同时在野外观测了其春、夏、秋季的土壤呼吸速率、温度(气温和地温)、湿度(空气相对湿度和土壤湿度)数据,分析它们之间的相关关系,并通过通径分析,获得不同季节对土壤呼吸影响最大的直接影响因子及间接因子,依此建立不同类别的多种回归模型,在精度检验及简单易行的原则上,得到各季节土壤呼吸预测的最优模型,且以这些模型的建模因子讨论强碱土土壤呼吸日和季节变化的机理。此外,在室内模拟了冬季低温环境下的土壤呼吸特征,以及在野外模拟不同降水强度下的土壤呼吸变化。最终以说明强碱土在不同环境下的土壤呼吸特征。主要研究结果如下:(1)强碱土土壤呼吸中,无机呼吸部分占到总的呼吸的99.37%。其主导了日变化和季节变化,有机呼吸部分的影响可忽略。(2)春、秋季土壤呼吸与气温、空气相对湿度和土壤湿度均达到了极显著相关,且与气温的相关性最强。夏季土壤呼吸与温、湿度四因子均存在极显著的相关关系,与地温的相关性最高。通径分析表明,气温是春、秋季土壤呼吸的最大直接影响因子,夏季则为地温因子,且三季节均以土壤湿度的间接作用最大。此外,温、湿度的耦合控制了土壤呼吸的变化,10cm处气温和土壤湿度所建的方程是春、秋季土壤呼吸的最佳预测模型,精度分别为92.67%和77.23%。而夏季土壤呼吸的最佳预测模型则为与10cm处气温、地温、空气相对湿度和土壤湿度所建的4因子方程,其估测精度为84.99%。(3)春、秋季的土壤呼吸日变化为单峰型,其峰值出现时间分别为14:00和10:00,日间段以释放CO2为主,夜间段则在大量的吸收CO2,但整体上春季以释放CO2为主(释放量为0.07μmol·m-2·s-1),而秋季则以吸收CO2为主(吸收量为0.05μmol·m-2·s-1)。夏季土壤呼吸日变化呈双峰型,第一峰值出现在9:00~10:00,第二峰值则出现在21:00左右,且其土壤呼吸速率仅在5:00~11:00期间以及21:00左右为正值,其余时段则为负值,其整体上吸收CO2,吸收量达到0.14μmol·m-2·s-1。模拟冬季土壤呼吸发现,低温下,强碱土能吸收大量的CO2,且温度越低,吸收的量越多。(4)强碱土土壤呼吸的变化机理,主要是土壤中的碳酸盐(Ca CO3等)与H2O和CO2的化学反应生成重碳酸盐而吸收CO2,使得夜间和日间的低温时段土壤呼吸速率值为负。而温度高的日间段,重碳酸盐遇热分解释放出CO2,但当温度达到一定的界限后(10cm处气温和地温分别超过30℃、26℃),高温反而激发了碳酸盐与H2O-CO2的反应速率而吸收大量的CO2,但前提是土壤湿度应保持在一个较高的水平。(5)小雨处理激发了土壤呼吸,在降水过程中,其比对照增加了320.69%,降水后的增长为58.82%,在降水后22h,土壤呼吸速率恢复到对照水平。中雨处理在降水过程中,其比对照减少了48.27%,但在降水后则整体增加了29.41%,降水后37h,土壤呼吸速率大致恢复到与对照相近水平。大雨处理使得强碱土能吸收更多的CO2,降水过程中和降水后的土壤呼吸速率,相较对照分别减少306.89%和188.24%。
[Abstract]:The soil inorganic carbon in arid and semi arid regions of the huge reserves, it is for the whole region and the global carbon cycle can not be ignored. This study determined by LI-8100 without vegetation growth in open soil carbon flux meter, alkali soil organic matter content of soil respiration. Rarely take soil column and field sterilization proportion through the comparison of the inorganic and organic soil respiration, soil respiration to determine the dominant mode of alkaline earth strong. At the same time in the field observation of the spring, summer and autumn, the soil respiration rate, temperature (temperature) and humidity (relative humidity and soil moisture) data, analysis of the relationship between them, and through path analysis through the different season the most direct impact factors and indirect factors on soil respiration, establish various different categories in the regression model, accuracy test and simple in principle, the The optimal model of soil respiration seasonal prediction, and the modeling of these models to discuss the mechanism of the change of factors of soil alkali soil respiration and the seasons. In addition, characteristics of soil respiration in winter with low temperature environment is simulated in laboratory, and in the field simulated rainfall intensity of soil respiration. Finally in order to illustrate the characteristics of soil respiration in alkali soil under different environmental conditions. The main results are as follows: (1) soil respiration in alkali, inorganic respiration accounted for the total respiration 99.37%. dominated the diurnal and seasonal changes, the effect of organic respiration part can be ignored. (2) the spring and autumn soil respiration and temperature, air relative humidity and soil humidity reached a significant correlation with temperature, and the correlation between soil respiration and temperature. The strongest in summer, there was a significant correlation between the four highest temperature and humidity factor correlation. Path analysis showed that the gas The temperature of soil respiration in autumn Shichun, the largest direct impact factor, summer is the temperature factor, and the three season are the indirect effects of soil moisture. Moreover, temperature change, humidity coupling control of soil respiration, the 10cm temperature and soil humidity equation is the best model of spring, autumn soil respiration, the accuracy is 92.67% and 77.23%. respectively and the optimal prediction model of soil respiration in summer is temperature, and soil temperature at 4 10cm, the equation of air relative humidity and soil moisture, the estimation accuracy of 84.99%. (3) spring, the diurnal change of soil respiration in autumn was single peak type, the peak time was at 14:00 and at 10:00 the day to release the CO2, at night in a large number of absorption of CO2, but the whole spring to release CO2 (release 0.07 mol - m-2 - s-1), and CO2 (mainly in autumn absorption absorption was 0.05 mol m-2. S-1). In summer, the diurnal change of soil respiration in Shuangfeng, the first peak in the 9:00~10:00, the second peak appeared at about 21:00, and the soil respiration rate only during 5:00~11:00 and around 21:00 in the rest time is negative, the absorption of CO2, reached 0.14 mol - m-2 - s-1. simulation of soil in winter breathing found absorption under low temperature, alkali soil can absorb a large amount of CO2, and the lower the temperature, the more the amount of absorption. (4) the change mechanism of alkali soil respiration, soil is mainly carbonate (Ca CO3) and H2O and CO2 chemical reaction of bicarbonate and absorption of CO2, the at the low temperature of soil respiration at night and daytime value is negative. While the daytime temperature is high, bicarbonate in thermal decomposition of the release of CO2, but when the temperature reaches a certain threshold (air temperature and soil temperature at 10cm were more than 30 DEG, 26 DEG C), but to stimulate carbon at high temperature The reaction rate of acid salt and H2O-CO2 and absorb a large amount of CO2, but the premise is the soil humidity should be maintained at a relatively high level. (5) the rain treatment stimulated soil respiration in the precipitation process, an increase of 320.69% compared with the control, after the rainfall of 58.82% growth in the precipitation of 22h after recovery of soil respiration the rate to the level of control. Moderate treatment in the precipitation process, the reduction of 48.27% compared with the control, but after rainfall in the overall increase of 29.41%, after precipitation 37h, soil respiration rate is restored to the control level. The heavy rain makes similar alkali soil can absorb more CO2, the precipitation process of soil respiration after neutralization precipitation compared with the control, respectively by 306.89% and 188.24%.

【学位授予单位】：新疆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S154

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