黄土高原退耕还草区土壤微生物群落研究

发布时间：2018-05-02 21:32

本文选题：黄土高原 + 植被恢复　；参考：《西北农林科技大学》2017年硕士论文

【摘要】：植被恢复作为防治水土流失和修复退化生态系统的有效手段,在黄土高原地区得到了广泛应用。植物群落的恢复和演替受到植物-土壤反馈机制的深刻影响,而微生物群落在其反馈机制和植物群落结构塑造中发挥着关键性作用。本文选取黄土高原退耕还草区不同恢复年限的草地作为主要研究对象,基于高通量测序的分子生物学技术,研究植被恢复过程土壤微生物群落结构、组成和功能多样性的响应以及植物-微生物群落相互作用的特征,揭示植被恢复对微生物分类和功能多样性以及地上-地下生物群落相互作用的影响机制。主要结论如下:(1)在微生物类群多样性方面:草地自然恢复显著地改变了土壤细菌和真菌群落结构,基于Bray-Curtis和Unifrac距离的统计分析表明,不同恢复年限的土壤细菌和真菌群落组成差异均显著。细菌群落中相对丰度最高的门为放线菌门(Actinobacteria),其次是变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)和绿弯菌门(Chloroflexi);而真菌群落主要由子囊菌门(Ascomycota)、担子菌门(Basidiomycota)和接合菌门(Zygomycota)构成。土壤细菌和真菌群落的alpha多样性均随着恢复年限的增加而显著提高,而两者群落组成的相似度均表现出显著的时间衰减趋势。细菌和真菌的结构、组成和多样性均受到环境因子的影响,其中p H、有机质和总氮是造成微生物类群构成差异的主要驱动因素。(2)在微生物功能多样性方面:宏基因组测序表明自然恢复草地和农田土壤微生物类群的功能alpha多样性和beta多样性均显著不同,自然恢复30年的草地存在最高的功能alpha多样性。在测定的环境因子中,土壤有机质是造成微生物群落功能多种性差异的主导因素。通过KEGG数据库比对发现,草地土壤微生物与能量代谢、碳水化合物代谢和外源物质降解与代谢相关的功能基因类群相对丰度较农田显著提高;而与氨基酸代谢、多糖合成与代谢、复制与修复和细胞生长与凋亡相关的功能基因在农田中具有较高的相对丰度;通过CAZy数据库比对发现,草地自然恢复增加了碳水化合物降解酶基因的相对丰度,包括GH3、GH13和GH15等类群。(3)植物-微生物群落相互作用方面:在草地恢复过程中地上植被和地下微生物群落间具有显著的相互作用,其中土壤细菌和真菌群落的alpha多样性均随着植物alpha多样性的增加而显著增大,植物群落的alpha多样性可以作为细菌和真菌群落alpha多样性的显著预测因子。在beta多样性方面,植物群落的beta多样性与土壤细菌和真菌群落的beta多样性具有明显的相关性,土壤环境因子对细菌和真菌群落也具有显著影响。植物群落和土壤环境因素对土壤细菌和真菌群落具有不同的影响力,植物群落对真菌群落的影响大于细菌群落,而土壤环境因子对真菌群落的影响却小于细菌群落,表明植被恢复过程中细菌和真菌群落的构建具有不同的环境选择过程。
[Abstract]:Vegetation restoration is widely used in Loess Plateau as an effective means to control soil erosion and restore degraded ecosystem. The restoration and succession of plant communities are deeply influenced by the plant-soil feedback mechanism, and the microbial community plays a key role in the feedback mechanism and the shaping of plant community structure. In this paper, the grassland with different restoration years in the Loess Plateau was selected as the main research object. Based on the molecular biological technology of high-throughput sequencing, the soil microbial community structure during vegetation restoration was studied. The response of composition and functional diversity and the characteristics of plant-microbial community interaction reveal the mechanism of vegetation restoration affecting microbial classification and functional diversity as well as the interaction between aboveground and underground biota. The main conclusions are as follows: in terms of microbial diversity: natural restoration of grassland significantly changed the structure of soil bacterial and fungal communities. Statistical analysis based on the distances of Bray-Curtis and Unifrac showed that, The composition of soil bacterial and fungal communities with different restoration years were significantly different. Actinobacteriae, Proteobacteriae, Acidobacteria, Acidobacteria) and Chloroflexium were the most abundant in the bacterial community, while the fungal community was mainly composed of Ascomycotataa, Basidiomycotata and Zygomycota. The alpha diversity of soil bacterial and fungal communities increased significantly with the increase of restoration years, and the similarity of the composition of the two communities showed a significant trend of time decay. The structure, composition and diversity of bacteria and fungi are affected by environmental factors. Among them, pH, organic matter and total nitrogen are the main driving factors for the difference of microbial composition. 2) in terms of microbial functional diversity: Macrogenome sequencing shows that functional alpha of soil microbial communities can be recovered naturally from grassland and farmland. Diversity and beta diversity were significantly different, There is the highest functional alpha diversity in grassland after 30 years of natural recovery. Among the environmental factors measured, soil organic matter is the leading factor for the diversity of microbial community function. The results of KEGG database analysis showed that the relative abundance of microbial and energy metabolism, carbohydrate metabolism and metabolism related to metabolism of exogenous substances were significantly higher than that of farmland, while amino acid metabolism was associated with microbial metabolism. The functional genes related to polysaccharide synthesis and metabolism, replication and repair, cell growth and apoptosis have high relative abundance in farmland. The natural recovery of grassland increased the relative abundance of carbohydrate degrading enzyme gene. Including GH3, GH13 and GH15) plant-microbial community interaction: there is significant interaction between aboveground vegetation and underground microbial community during grassland restoration. The alpha diversity of soil bacterial and fungal communities increased significantly with the increase of plant alpha diversity, and the alpha diversity of plant communities could be used as a significant predictor of alpha diversity of bacterial and fungal communities. In terms of beta diversity, the beta diversity of plant communities was significantly correlated with the beta diversity of soil bacteria and fungal communities, and soil environmental factors had significant effects on bacterial and fungal communities. Plant communities and soil environmental factors have different influences on soil bacteria and fungi communities. Plant communities have more influence on fungal communities than bacterial communities, but soil environmental factors have less influence on fungal communities than on bacterial communities. The results showed that the construction of bacterial and fungal communities had different environmental selection processes during vegetation restoration.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S812.2

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