温度变化对土壤有机碳矿化及其动力学特征的影响

发布时间：2018-06-02 09:02

本文选题：土壤有机碳 + 矿化　；参考：《西南大学》2015年硕士论文

【摘要】：采用野外采样和室内培养试验,研究了不同土地利用类型(林地和旱地)下的石灰土和黄壤(旱地)表层土壤有机碳(SOC)矿化对温度变化的响应。三种供试土样分别采自贵州省普定县天龙山区域的典型林地和旱地的0～10cm表层。针对3种供试土壤,设置2种温度培养模式：①恒温模式,包括25℃、20℃、15℃,分别简称为HT-25、HT-20、HT-15;②变温处理,范围：15℃～25℃,变温间隔12h,每24h为1个周期,简称为BT-15/25,其中变温处理和20℃恒温处理的积温相同,培养时间为56d。利用培养过程中测得的相关数据,系统研究温度变化对土壤有机碳矿化及其动力学特征的影响,为全面认识土壤有机碳矿化的温度效应以及有机碳矿化模型的构建提供基础资料和科学参考。研究结果如下：(一)相同培养温度条件下,3种土壤相同培养时间段内的日均矿化量和累积矿化量大小顺序为：森林石灰土旱地石灰土黄壤,且差异均达到显著性水平(P0.05)。不同培养温度条件下,3种土壤前14d的有机碳平均矿化速率显著高于其后42d的矿化速率,培养前14d释放的CO2量约占总矿化量的60%～68%,这表明前14d的矿化速率决定了整个培养期内的有机碳累积矿化量。恒温培养条件下,3种土壤的累积矿化量和矿化强度随着培养温度的升高而显著增加。森林石灰土BT-15/25处理的有机碳累积矿化量和矿化强度显著低于HT-20处理,黄壤BT-15/25处理的有机碳累积矿化量和矿化强度则显著高于HT-20处理,旱地石灰土2种温度处理之间的累积矿化量和矿化强度则无明显差异,说明培养温度模式(恒温和变温)的变化显著影响土壤有机碳的矿化,通常利用恒温培养下获得的土壤矿化数据来预测和衡量田间土壤碳矿化水平的方法是有待商榷的,判定有机碳矿化对变温环境的响应程度是准确估算土壤CO2排放量的关键。(二)土壤有机碳累积矿化量与有机碳含量呈显著或极显著正相关(P0.05、P0.01),表明土壤有机碳含量是控制矿化过程的重要因素。3种土壤变温处理的累积矿化量和矿化强度总是介于HT-25和HT-15处理之间,说明变温处理的有机碳矿化受到温度变化范围的限制。受土地利用和植被类型的影响,森林石灰土和2种旱地土壤的表层有机碳含量和组成差异显著,结合土壤有机碳含量和组成、Q10值和矿化强度之间的关系分析可知,有机碳含量和组成等自身属性可能是影响其矿化过程对外界温度变化响应的重要原因。(三)森林石灰土变温处理的潜在矿化量显著低于HT-20处理,且C0/SOC明显小于旱地石灰土和黄壤,说明变温环境中森林石灰土微生物分解有机碳的能力减弱,微生物对碳源的利用效率降低。(四)培养过程中土壤的κs随着温度的升高而升高,这表明随着温度的升高土壤微生物利用难分解碳库的能力逐渐增强。整个培养期内,3种土壤的难分解有机碳含量与累积矿化量的比值达到近40%,这显示在有机碳矿化过程中难分解碳库与易分解碳库有着同等重要的作用。通过比较分析变温处理和恒温20℃处理条件下森林石灰土、旱地石灰土和黄壤有机碳矿化动力学方程中各参数的变化规律,发现变温环境主要通过改变易分解碳库的含量和难分解碳库的矿化速率常数来影响土壤有机碳矿化过程。(五)整个培养期间,由于土壤可溶性有机碳的溶出量与有机碳含量的关联性,有机碳含量较高的森林石灰土的可溶性有机碳含量始终高于旱地石灰土和黄壤。土壤类型和所处温度条件的不同,使土壤可溶性有机碳的溶出量亦有差异,这主要与土壤有机碳的温度敏感性和不同温度条件下土壤微生物群落活性有关。3种土壤不同温度条件下的可溶性有机碳含量与有机碳日均矿化量均呈极显著正相关,表明制约土壤可溶性有机碳生成是温度影响有机碳矿化的一个重要途径。(六)由于土壤微生物量碳与土壤有机碳含量的相关性,森林石灰土的微生物量碳含量显著高于旱地石灰土和黄壤。除HT-25处理条件下黄壤的微生物量碳含量与日均矿化量显著相关外,各处理的土壤微生物量碳含量与有机碳的日均矿化量均无显著相关性；土壤微生物量碳也不能有效反映升温过程中以及恒温和变温处理之间土壤有机碳矿化的差异,该现象表明,温度条件不能通过显著改变土壤微生物数量来影响有机碳矿化过程。温度变化可能通过影响土壤微生物群落的组成、结构和活性从而改变微生物利用有机碳的能力,进而对土壤有机碳矿化过程产生影响。结合矿化动力学分析可知,土壤微生物群落活性的变化是影响有机碳矿化的关键,温度能通过改变土壤微生物群落的活性来影响有机碳矿化过程。
[Abstract]:The response of soil organic carbon (SOC) mineralization in calcareous soil and yellow soil (dryland) under different land use types (Woodland and dry land) to temperature changes under different land use types (Woodland and dry land) was studied by field sampling and indoor culture test. Three samples were collected from typical woodland and 0 ~ 10cm surface of dry land in Tianlong mountain area of Puding County, Guizhou province. 3 kinds of soil samples were provided. 2 temperature cultivation modes were set up in the test soil: (1) constant temperature mode, including 25, 20, 15 C, respectively for HT-25, HT-20, HT-15, and variable temperature treatment, range: 15 C to 25 C, variable temperature interval 12h, 1 cycles per 24h, which was called BT-15/25, in which the temperature treatment was the same as that of the constant temperature treatment at the same temperature, and the incubation time was 56d. utilization and culture process. The influence of temperature change on soil organic carbon mineralization and its dynamic characteristics is systematically studied in this paper, which provides basic information and scientific reference for a comprehensive understanding of the temperature effect of soil organic carbon mineralization and the construction of organic carbon mineralization model. The results are as follows: (1) 3 kinds of soil Xiang Tongpei under the same incubation temperature. The order of daily average mineralization and accumulated mineralization in the period of the cultivation period is: the forest calcareous lime soil yellow soil in the forest calcareous soil, and the difference reached significant level (P0.05). The average mineralization rate of the organic carbon in the 3 kinds of soil before the different culture temperatures is significantly higher than that of the subsequent 42d, and the CO2 amount released by the 14d before the culture is about the total ore. The mineralization rate of 14d was 60% ~ 68%. The cumulative mineralization of organic carbon in the whole culture period was determined by the mineralization rate of the whole culture period. The cumulative mineralization and mineralization intensity of the 3 soils increased significantly with the increase of incubation temperature. The cumulative mineralization and mineralization intensity of organic carbon in the forest calcareous soil BT-15/25 treatment was significantly lower than that of HT-2. 0 treatment, the cumulative mineralization and mineralization intensity of organic carbon in the yellow soil BT-15/25 treatment was significantly higher than that of HT-20 treatment. There was no significant difference in cumulative mineralization and mineralization intensity between 2 temperature treatments in dryland, indicating that the change of incubation temperature model (constant temperature and variable temperature) significantly affected the mineralization of soil organic carbon, usually using constant temperature culture. The method to predict and measure the soil carbon mineralization level in the field is debatable. The determination of the response degree of the organic carbon mineralization to the variable temperature environment is the key to the accurate estimation of soil CO2 emissions. (two) the cumulative mineralization of soil organic carbon has significant or extremely significant positive correlation with the organic carbon content (P0.05, P0.01). The content of organic carbon in soil is an important factor in controlling the mineralization process. The cumulative mineralization and mineralization intensity of.3 soil temperature treatment are always between HT-25 and HT-15 treatments. It shows that the mineralization of organic carbon in the variable temperature treatment is limited by the range of temperature change. There are significant differences in the content and composition of the surface organic carbon. According to the relationship between the soil organic carbon content and composition, the relationship between the Q10 value and the mineralization strength, it is found that the organic carbon content and composition may be the important reasons for the response of the mineralization process to the external temperature change. (three) the potential mineralization of the forest calcareous soil temperature change treatment is obvious. It was lower than HT-20 treatment, and C0/SOC was obviously less than calcareous soil and yellow soil in dry land, which indicated that the ability of microorganism to decompose organic carbon in forest calcareous soil decreased and the efficiency of microbial utilization of carbon source decreased. (four) the kappa s of soil increased with the increase of temperature during the process of culture, which indicated that the soil microorganism was used with the increase of temperature. The ability to decompose carbon pool is gradually enhanced. The ratio of the organic carbon content to the cumulative mineralization of the 3 soils in the whole culture period is nearly 40%, which shows that the decomposition of carbon pool and the decomposable carbon pool in the process of organic carbon mineralization has the same important role. By comparing and analyzing the forest stone under the temperature treatment and the constant temperature at 20 degrees C The variation of various parameters in the kinetic equation of mineral carbon mineralization in lime soil, dryland calcareous soil and yellow soil found that the temperature changing environment mainly influenced the mineralization process of soil organic carbon by changing the content of the decomposable carbon pool and the mineralization rate constant of the refractory carbon pool. (five) the dissolution of soil soluble organic carbon and the amount of soluble organic carbon in the whole culture period The soluble organic carbon content of forest calcareous soil with high organic carbon content is always higher than that of dryland calcareous soil and yellow soil. The difference of soil type and temperature conditions makes the soluble amount of soluble organic carbon dissolve in soil, which is mainly due to the temperature sensitivity of soil organic carbon and soil under different temperatures. The content of soluble organic carbon in different temperature conditions of.3 species was significantly correlated with the daily average mineralization of organic carbon, indicating that the restriction of soil soluble organic carbon formation was an important way for temperature to affect the mineralization of organic carbon. (six) the correlation between soil microbial biomass carbon and soil organic carbon content was related. The microbial biomass carbon content of forest calcareous soil was significantly higher than that of dryland calcareous soil and yellow soil. In addition to the HT-25 treatment, the microbial biomass carbon content was significantly correlated with the daily average mineralization, and there was no significant correlation between the soil microbial biomass carbon content and the daily average mineralization of organic carbon, and the soil microbial biomass carbon could not be effectively reversed. The difference in soil organic carbon mineralization between temperature and temperature treatment is shown, which indicates that temperature can not affect the mineralization process of organic carbon by significantly changing the amount of soil microorganism. The temperature change may change the organic carbon by influencing the composition, structure and activity of soil microbial community. The ability to affect the mineralization process of soil organic carbon, combined with the analysis of mineralization kinetics, the change of soil microbial community activity is the key to influence the mineralization of organic carbon, and the temperature can affect the mineralization process of organic carbon by changing the activity of soil microbial community.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S153.6

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