神农架森林土壤微生物沿海拔分布格局及形成机制

发布时间：2018-01-12 07:18

本文关键词：神农架森林土壤微生物沿海拔分布格局及形成机制　出处：《清华大学》2016年博士论文　论文类型：学位论文

【摘要】：微生物作为陆地生态系统的分解者,在调控生物地球化学过程中起着极其重要的作用,因此认识微生物空间分布格局及形成机制具有十分重要的意义。由于技术手段的限制,微生物地理学分布的研究相对滞后于大型动植物。随着宏基因组技术在微生物地理学领域中的应用,近年来发现土壤微生物群落结构具有一定的地理分布格局,突破了学术界对于微生物全球性随机分布的传统认识。神农架自然保护区位于湖北省西北部,是我国中北亚热带的过渡地区,也是我国东部平原丘陵区向中部山地区的过渡地区,其特殊的地理环境和气候条件孕育了十分丰富的生物资源。本研究以神农架自然保护区为研究对象,采用高通量测序以及基因芯片技术,率先综合物种水平以及功能基因水平揭示微生物地理学分布随着海拔的变化规律。本研究发现:(1)微生物在物种水平及功能基因水平的分布规律及构建机制不同。微生物物种组成沿海拔梯度呈明显地带性分布特征,符合中性理论,扩散限制在物种分布中发挥重要作用;而微生物功能基因组成则呈大范围广泛分布,符合生态位理论,环境理化性质在功能基因分布中发挥重要作用。(2)微生物群落控制因子随着研究尺度的不同而改变。在沿海拔梯度分布范围下,地理距离是影响微生物物种组成的主要因素,而环境理化性质是影响微生物功能基因组成的主要因素。在更小尺度下,林线处微生物群落结构主要受温度控制,而较低海拔的阔叶林其微生物群落则主要受到土壤有机质数量与质量的控制。(3)微生物结构与功能的关系受到考察类群的影响。考虑所有类群及功能基因种类,发现微生物物种组成与功能基因组成无明显相关关系,说明微生物整体群落存在功能冗余现象。而针对林线上下林型的氨氧化菌以及硝化基因(amoA)的相关性分析发现,微生物氨氧化菌多样性与amoA呈显著正相关关系,功能冗余程度低。(4)微生物功能基因组成对外界环境有良好的指征作用。整体功能基因组成与环境理化性质呈显著相关关系;林线处氮循环基因与土壤中NH4+-N、NO3--N存在相关关系;阔叶林中难降解碳基因的变化与环境中易降解碳的含量相吻合。体现了微生物功能基因组成对于指征外界环境变化的灵敏性。
[Abstract]:As the decomposers of terrestrial ecosystems, microorganisms play an extremely important role in regulating biogeochemical processes. Therefore, it is very important to understand the spatial distribution pattern and formation mechanism of microorganisms. With the application of macrogenome technology in the field of microbiogeography, it has been found that the soil microbial community structure has a certain geographical distribution pattern in recent years. Shennongjia Nature Reserve is located in northwestern Hubei Province and is a transitional region of central and northern subtropical zone in China. It is also a transitional area from the hilly region of the eastern plain to the central mountain area, whose special geographical environment and climatic conditions have given birth to very rich biological resources. This study takes Shennongjia Nature Reserve as the research object. High throughput sequencing and gene chip technology were used. It is the first to synthesize species level and functional gene level to reveal the regularity of microbial geography distribution with altitude. The distribution and construction mechanism of microorganisms at species level and functional gene level were different. In accordance with the neutral theory, diffusion limitation plays an important role in the distribution of species. The composition of microbial functional genes is widely distributed, which accords with niche theory. Environmental physical and chemical properties play an important role in functional gene distribution. Geographical distance is the main factor affecting the composition of microbial species, and the physical and chemical properties of environment are the main factors affecting the composition of microbial functional genes. In a smaller scale, the structure of microbial community in the forest line is mainly controlled by temperature. The microbial community of broad-leaved forest at lower altitude is mainly controlled by the quantity and quality of soil organic matter. The relationship between microbial structure and function was influenced by the study group. All the groups and functional gene types were considered. It was found that there was no significant correlation between microbial species composition and functional gene composition. The results showed that there was functional redundancy in the whole microbial community, and the correlation analysis of ammonia-oxidizing bacteria and nitrification gene of the upper and lower forest type was found. The diversity of microbial ammonia-oxidizing bacteria was positively correlated with amoA. The functional gene composition of microorganism has a good indication to the external environment, and the whole functional gene composition has a significant correlation with the physical and chemical properties of the environment. There was a correlation between nitrogen cycling gene and NH4 -Nnnno _ 3-N in soil. The change of refractory carbon gene in broadleaved forest is consistent with the content of easily degradable carbon in the environment, which reflects the sensitivity of microbial functional gene composition to indicating the change of external environment.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S714.3

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