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题名: 北京东灵山土壤细菌海拔格局及驱动机制
作者: 厉桂香1
学位类别: 博士
答辩日期: 2017-05
授予单位: 中国科学院大学
授予地点: 北京
导师: 马克明
关键词: 土壤细菌 ; 海拔梯度 ; elevational gradient ; 树线 ; treeline ; 高通量测序 ; high throughput sequencing ; 功能预测 ; predicted functional gene ; soil bacteria
其他题名: Soil bacterial distribution pattern and mechanism along elevational gradient in Dongling Mountain, Beijing
学位专业: 生态学
中文摘要: 土壤微生物多样性的空间格局是目前生物地理学的研究热点。海拔梯度作为多种生物和非生物因素在垂直方向上的综合反映,其短距离骤变的环境条件成为研究土壤微生物多样性分布的理想场所。由于微生物的特性和技术手段的限制,土壤微生物海拔格局研究相较于动植物滞后。土壤微生物是否同动植物一样呈现明显的海拔格局?植物群落怎样影响土壤微生物的海拔格局?其格局及驱动因子在树线处如何转变?这些问题尚无明确答案。 本研究采用Illumina MiSeq高通量测序的方法,对北京东灵山不同植被类型(森林-草甸)以及不同生活型植物下的土壤细菌群落进行研究,旨在揭示土壤细菌的海拔分布规律,及其与植被、土壤以及空间因素的关系,相关研究结果如下: (1)植被类型及土壤理化性质在树线上下不同,导致土壤细菌多样性分布格局在树线处发生了转变。在森林内,土壤细菌多样性呈现下凹型的分布格局(影响因素为土壤温度、pH、碳氮比),而在树线之上呈现单调递减的趋势(影响因素为pH、有效磷)。土壤细菌的群落结构也在树线上下差异显著,并且主导因素不同,在森林中为土壤pH,在草甸中为土壤温度。草甸中环境因子对于土壤细菌群落结构的解释率远高于森林中。草本植物与土壤细菌丰富度在森林和草甸中均不相关,但是与土壤细菌的群落结构显著相关。 (2)植被类型的不同也导致土壤细菌群落功能在树线上下的差异。采用PICRUSt基因预测分析方法,对辽东栎林及树线之上草甸的土壤细菌群落及功能进行对比研究,结果表明土壤细菌群落结构与预测功能均发生了变化。在39个二级预测功能分类中有10个子功能的相对多度在森林和草甸中具有明显差异。其中,其他次生产物代谢的生物合成、转录、多糖生物合成和代谢、酶家族、信号分子及交互作用、环境适应、细胞生长和死亡等的功能基因在森林中明显高于草甸中;而维他命及辅因子代谢、膜运输、内分泌系统等的功能基因在草甸中偏高。 (3)不同生活型植物下土壤细菌Hill多样性和群落结构的研究表明,不同生活型植物对土壤细菌多样性海拔分布的影响具有差异性。乔木下与灌木下土壤细菌物种丰富度同地上植物一样均呈现下降的海拔格局,草本下的土壤细菌物种丰富度与草本植物都呈现下凹型的海拔分布格局。同一生活型植物下,土壤细菌稀有类群与优势类群的海拔格局不同,土壤细菌物种丰富度海拔格局主要由稀有类群驱动。木本植物与土壤细菌的相关性较弱,但草本植物与地下细菌群落显著相关。 (4)土壤细菌群落沿海拔倾向于系统发育聚集且群落结构沿海拔没有呈现明显的距离衰减关系,意味着生态位理论的环境过滤作用在细菌群落的构建中起着重要的作用。系统发育结构及beta多样性分析显示,土壤pH、碳、氮是重要的环境过滤因子,尤其是土壤pH,影响森林内木本植物下土壤细菌群落构建。 本研究揭示了土壤细菌沿海拔梯度呈现明显的规律性分布且在树线处发生转变,明确了土壤细菌受地上植被及土壤因子的重要影响,研究结果对于系统认识土壤微生物群落多样性的形成机制及预测土壤微生物对环境变化的响应提供科学依据。
英文摘要: The spatial distribution pattern of soil microbial diversity has become a hotspot issue in biogeography currently. As a comprehensive reflection of a variety of biotic and abiotic factors in the vertical direction, elevational gradient has been seen as an ideal place for the study of soil microbial diversity distribution owing to dramatic changes in environmental conditions over short geographic distances. However, due to properties of microorganisms and technical limitations, the study of soil microbial distribution pattern along elevational gradient is lagged behind. If the soil microbial diversity show an elevational pattern just as the plant and animal? How does plant communities affect the distribution pattern of soil microbes along elevational gradient? Whether the distribution pattern and underlying mechanism vary at the treeline? Answers to these questions are still unclear In this study, using Illumina MiSeq, we investigated soil bacteria under different vegetation types (forest-meadow) and different life form plant in Dongling Mountain, Beijing. We aimed to reveal the elevational distribution pattern of soil bacteria and underlying environmental correlates, such as vegetation, soil, and spatial factors. The results showed as follows: (1) Elevational diversity pattern of soil bacteria shifted at the treeline in responding to changes in vegetation type and soil properties. The elevational diversity pattern of soil bacteria showed a hollow elevational pattern in the forest (correlated with soil temperature, pH, and C:N ratio) and a significantly decreasing pattern in the meadow (correlated with soil pH, and available phosphorus). The bacterial community structure was also distinct between the forest and meadow, relating to soil pH in the forest and soil temperature in the meadow. The explaining probabilities were much higher in the meadow than in the forest. Soil bacteria did not follow the distribution pattern of herb diversity, but bacterial community structure could be predicted by herb community composition. (2) Predicted functional categories and structure of soil bacteria also shifted at the treeline. We investigated the soil bacterial community and function of a Quercus liaotungensis forest and the meadow above the treeline using PICRUSt analysis. The results showed that bacterial community structure and the predicted functional profiles changed at the treeline. Within the 39 predicted functional categories at KEGG pathway hierarchy level 2, 10 categories show obviously difference between forest and meadow. Relative abundance of gene families related to biosynthesis of other secondary metabolites, transcription, glycan biosynthesis and metabolism, enzyme families, signaling molecules and interaction, environmental adaptation, growth and death tended to be higher in the forest. While those related to metabolism of cofactors and vitamins, membrane transport, endocrine system were significantly higher in the meadow. In future studies of microbial ecology, more attention should be paid to community composition and functioning instead of species diversity. (3) Different life form plant had an effect on the distribution of soil bacterial diversity. The species richness of soil bacteria under tree and shrub layer showed significantly decreasing elevational patterns like aboveground plants, and the species richness of herb and soil bacteria under herb layer both showed hollow pattern. Hill diversity showed different elevational patterns under same life form plant. The elevational patterns of soil bacterial species richness were mostly driven by rare groups. Woody plant were less relevant to soil bacteria, but the bacterial community under the herb layer was significantly associated with herb plants. (4) Bacterial communities tended to be phylogenetically clustered and did not show a significant elevational distance-decay distribution pattern along elevational gradient, suggesting the importance of environmental filtering processes in structuring the bacterial community. Phylogenetic and beta diversity analysis showed that soil pH, carbon and nitrogen were important environmental filter factors, especially pH, which played an important role in the assembly of bacterial community under woody plant. In summary, we found that the soil bacteria showed significant distribution pattern along elevational gradient and shifted at the treeline. Soil bacteria were affected by aboveground vegetation and soil factors. Our results provide a scientific basis for understanding the underlying mechanisms underlying biogeographical patterns of soil microbial communities and predicting how microorganisms should respond to environmental changes.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38659
Appears in Collections:城市与区域生态国家重点实验室_学位论文

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