Knowledge Resource Center for Ecological Environment in Arid Area
| 藏北高原不同类型草地固碳微生物群落及其固碳能力研究 | |
| 其他题名 | Form I autotrophic community and their CO2 fixing ability in different grassland soils on northen Tibetan |
| 赵康 | |
| 出版年 | 2018 |
| 学位类型 | 博士 |
| 导师 | 孔维栋 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 以卡尔文-本森（CBB）循环为主要碳固定途径的生物固碳作用在C元素地球化学循环中起到重要的作用，是自然界最重要的CO2固定途径。通过CBB循环，生物体将CO2合成为六碳糖，并向生态系统中输入能量。本文在样带取样调查及原位监测的基础上，采用多种分子生态学方法，在DNA及RNA水平上对藏北高原草地土壤form I固碳微生物进行了深入的研究。论文的主要研究内容及结果如下：（1）藏北高原草地表层土壤固碳微生物数量、结构及其固碳速率室内同位素标记培养了青藏高原北部19个草地样点表层（0-1cm）土壤，阐明了其固碳能力，并在DNA水平研究了土壤form I类固碳微生物群落分布及其环境影响因子。结果表明，form IC cbbL基因丰度最高（107 copies/g dry soil），其次为form IAB类（104-107 copies/g dry soil），且随着草地类型由荒漠草原向典型草原及草甸草原的转变，土壤cbbL基因丰度逐渐升高。同时，典型草原土壤13CO2固定速率最高（29.59 mg/kg dry soil d）。荒漠草原土壤13CO2固定速率稍低于草原土壤，二者显著高于草甸草原土壤（18.21 mg/kg dry soil d）。环境因子分析发现，年平均降水量是影响土壤固碳微生物群落结构及土壤13CO2固定速率的关键环境因子，其通过直接及间接（影响地上植被生物量、有机质、铵态氮及pH）效应影响土壤固碳微生物的数量及群落结构，进而影响土壤13CO2固定速率。（2）绿藻、蓝细菌及根瘤菌属固碳微生物是藏北高原草地土壤最活跃的固碳微生物类群应用稳定性同位素标记培养（DNA-SIP）及氯化铯梯度分层技术，在DNA及RNA水平上进一步研究了三类典型草地土壤固碳微生物特征。结果表明，form IAB类的cbbL基因表达量最高，为106 copies/g soil。绿藻（Chlorophyta）比蓝细菌（Cyanobacteria）cbbL基因表达量更高，其能够转录更多的cbbL基因。form IC类微生物cbbL基因表达量较低（104 copies/g soil），且主要为根瘤菌属（rhizobiales）固碳微生物。（3）土壤固碳微生物群落及固碳能力的原位监测研究在纳木错站（代表典型草原），首先通过原位监测定量了土壤CO2固定能力。其次在DNA水平分析了form I固碳微生物对土壤CO2固定过程的贡献、主要固碳微生物类群（form IAB及IC）群落结构、活跃固碳微生物类群及其环境影响因子。结果发现，土壤GPP表具有明显的单峰型季节性变化规律，峰值出现在7月（70 mg CO2/m2 h）。同时，form IAB类微生物为生物结皮层土壤的主要微生物固碳功能类群，其cbbL基因表达量最高（105 copies/g soil），且主要集中于日出后的8时及10时。而以根瘤菌属为主的form IC类微生物在原位状态下仍然能够进行cbbL基因的表达（103-104 copies/g soil）。结合环境因子的分析发现，土壤含水量及铵态氮含量为影响form IAB群落结构季节性变化的主要因子，土壤温度为影响form IC群落结构的主要环境因子。 |
| 英文摘要 | Calvin-Benson-Bassham (CBB) cycle as the main biological carbon fixing pathway plays an important role in C geochemical cycle, is one of nature's most important CO2 fixation pathway. Through the CBB circulation, organisms synthesize CO2 into six carbon sugar, inputing energy to the ecosystem. On the basis of large scale investigation and in situ monitoring method, we explored the Tibetan grassland soil form I autotrophic microorganisms by using a variety of molecular ecology in DNA and RNA level. The main research contents and results are as follows:(1) Soil form I autotrophic microbial abundance, community structure and the rate of CO2 fixing rate in the northern Tibet plateau grassland soilsSurface (0-1 cm) soils from 19 northern Tibetan plateau grassland sites were incubated by using isotope labeling method, to illustrate its carbon sequestration ability, and study the soil form I autotrophic microbial community distribution and environment impact factors. The results showed that with the grassland types changed from desert grassland to the Steppe and meadow grassland, soil form I cbbL gene abundance gradually rised, form IC cbbL gene had the highest abundance (107 copies/g dry soil), followed by form IAB (104-107 copies/g dry soil). At the same time, the Steppe soil 13CO2 fixation rate was the highest (29.59 mg/kg dry soil d). Desert grassland soil 13CO2 fixation rate slightly lower than that of Steppe soil, meadow soil (18.21 mg/kg dry soil d) was significantly lower than both. Environmental factor analysis revealed that the mean annual precipitation (MAP) affected soil carbon 13CO2 fixing rate and microbial community structure as the key environmental factors. Through the direct and indirect influence (the ground vegetation biomass, organic matter, ammonium nitrogen and pH), the MAP effected soil autotrophic abundance and community structure.(2) The green algae, cyanobacteria and rhizobium genus autotrophic microorganisms were the most active in northern Tibetan grassland soil.Stable isotope labeling (DNA-SIP) and cesium chloride gradient layered technology were used to further study the soil autotrophic microbial characteristics on DNA and RNA level. The results showed that the form IAB had the highest amount of cbbL gene expression activiy, is 106 copies/g soil. Chlorophyta had higher cbbL gene expression activity than Cyanobacteria, it can express more cbbL gene. Form IC autotrophs had low cbbL gene expression activity (104 copies/g soil), and the autotrophs mainly belong to rhizobium genus.(3) Soil carbon sequestration capacity and form I autotrophic community based on in situ monitoring methodIn namco Steppe (representative), firstly we quantitatively monitored the soil CO2 fixation ability in situ. Secondly analysised the relations between form I autotrophs and the soil CO2 fixing rate, and autotrophic (form the IAB and IC) community structure, active soil autotrophs and their environmental impact factors in DNA and RNA level. The results showed that soil GPP had obviously seasonal variation, peak appears in the July (70 mg CO2/m2 h). At the same time, form IAB autotrophs was the main CO2 fixing microbes in biological crusts soils. It had the highest cbbL gene expression activity (105 copies/g soil), and mainly at 8 and 10 a.m. Form IC autotrophs had lower cbbL gene expression activity in situ (103-104 copies/g soil), and mianly belong to rhizobial genus. Environmental factor analysis revealed that the soil water content and ammonium content was the main factor affecting the form IAB community structure, soil temperature was the main environmental factor affecting the form IC community structure. |
| 中文关键词 | 生物固碳 ; 固碳能力 ; 青藏高原 ; 草地土壤 ; 固碳微生物 |
| 英文关键词 | Form I Rubisco Carbon fixing Tibetan plateau Grassland soil |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院青藏高原研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288040 |
| 推荐引用方式 GB/T 7714 | 赵康. 藏北高原不同类型草地固碳微生物群落及其固碳能力研究[D]. 中国科学院大学,2018. |
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