温带典型草原植被退化对土壤细菌群落结构的影响

发布时间：2017-12-27 06:23

  本文关键词：温带典型草原植被退化对土壤细菌群落结构的影响　出处：《内蒙古大学》2017年硕士论文　论文类型：学位论文

  更多相关文章： 温带典型草原 植被退化 高通量测序 细菌群落结构

【摘要】：土壤微生物在土壤生态系统中扮演着重要的角色,作为土壤微生物的重要组成部分—土壤细菌,在整个土壤生态系统中具有举足轻重的地位,它不仅可以促进生态系统的能量流动和物质循环,同时也是控制生态系平衡运作的重要指标。近年来,我国在此领域的研究主要集中在气候变化对土壤细菌生境影响以及不同土地利用方式对土壤养分、土壤细菌的影响,但是在植被-土壤-细菌三者之间的相互作用关系没有进一步阐明。本研究以内蒙古自治区锡林郭勒市毛登牧场"内蒙古大学草地生态学研究基地"温带典型草原为研究对象,通过高通量测序的方法,研究了4种退化样地(羊草轻度、大针茅轻度、中度和重度退化)的植物群落组成、土壤理化性质以及土壤细菌群落组成,分析植被-土壤-细菌群落结构之间的变化规律,对于温带典型草原土壤微生物资源的开发和保护其生态环境具有深远的意义。研究结果表明:(1)0-40 cm地上生物量随着退化加重而减少,表现为羊草轻度大针茅轻度中度重度退化。地上优势种氮含量在不同退化样地的分布差异显著,重度退化样地中每个优势种含氮量均为最高(P0.05)。地下根系氮含量也具有显著差异,中度退化样地最高(P0.05),这可能是因为中度退化样地的非禾本科植物和C3植物的总量要高于其余三种类型样地,所以中度退化样地的地下根系氮含量要高于其余三种退化样地。(2)通过实验室分析测得温带典型草原四种退化样地的土壤理化性质,结果表明只有0-40 cm 土壤粒度随着退化程度加重,粉粒所占比重逐渐下降,而黏粒的比例不断上升。这可能是因为草地退化加快了土壤风蚀的速度,进而使得土壤颗粒粒径变大。而在0-40 cm表层中重度退化样地的土壤有机碳、碱解氮和有效磷含量均为最低。(3)通过高通量测序技术可知,温带典型草原4种退化样地土壤中所有的150213条序列中共发现27个门、56个纲、243个科、1000个属,前6种主要细菌门比重总和为55.97%,这些细菌是优势菌类,这也说明虽然各样地退化程度不同,但是4种样地的具有相类似的微生物生境。然而,土壤个别细菌门在不同样地间变化较为明显。(4)四种退化样地中土壤细菌种系型丰富度和多样性差异不显著(P0.05),两者没有随着植被退化表现出响应关系,中度退化样地的土壤细菌种系型丰富度与多样性均为最高,这说明退化对于土壤细菌多样性的影响可能也符合"中度干扰假说"。其中,土壤中碱解氮和含水量是影响土壤细菌多样性的环境因子。在门、纲、目、科和属五种等级上不同退化样地种细菌分布存在差异,这说明温带典型草原的退化会导致某种细菌群落发生显著变化,但具体何种因素导致土壤细菌群落结构变化由于时间原因没能深入研究。
[Abstract]:Soil microorganisms play an important role in soil ecosystem, soil microorganism as an important part of soil bacteria, has an important position in the whole soil ecosystem, it can not only promote the energy flow and material circulation of ecological system, ecological balance is an important indicator of control system operation at the same time. In recent years, the research in this field mainly focused on the effect of climate change on soil bacterial habitat and the effects of different land use methods on soil nutrients and soil bacteria. However, the interaction between vegetation and soil bacteria three has not been further elucidated. This study takes the Inner Mongolia Autonomous Region City Xilinguole MAODENG pasture "base" of grassland ecology Inner Mongolia University temperate grassland as the research object, through the method of high-throughput sequencing, 4 kinds of degradation plot (Leymus chinensis Stipa grandis mild, mild, moderate and severe degradation) composed of physicochemical properties and composition of plant communities in soil and soil bacteria community, analysis of variation of vegetation soil bacterial community structure, which has profound significance for the development and the temperate typical grassland soil microbial resources to protect the ecological environment. The results showed that: (1) the biomass of 0-40 cm on the ground decreased with the deterioration, which showed mild moderate severe degeneration of Stipa Leymus. The nitrogen content of the dominant species on the ground was significant in different degenerate plots, and the nitrogen content of each dominant species in the severe degraded land was the highest (P0.05). With the nitrogen content of root was significantly difference, moderate degraded plot of the highest (P0.05), this may be because the total amount of moderate degraded plot of non gramineous plants and C3 plants are higher than those of the other three types, so the root nitrogen content of moderate degraded plot is higher than the other three kind of degradation. (2) through laboratory analysis, the physical and chemical properties of four degraded plots in temperate steppe were measured. The results showed that only 0-40 cm soil particle size increased with the deterioration degree, and the proportion of powder decreased gradually, and the proportion of clay increased. This may be because grassland degradation accelerates the speed of soil erosion and increases the particle size of the soil. In the 0-40 cm surface, the soil organic carbon, alkali hydrolysable nitrogen and available phosphorus were the lowest. (3) by high-throughput sequencing showed that 4 kinds of typical temperate grassland soil degradation in 150213 sequences were found in all 27 doors, 56 classes, 243 families, 1000 genera, 6 kinds of bacteria in the door before the proportion of total 55.97%, these bacteria were the dominant fungi, which also said that although different kinds of degradation degree, but 4 kinds of samples with similar microbial habitat. However, the changes in soil individual bacterial doors were more obvious. (4) four kinds of degraded soil bacterial phylotype richness and diversity were not significantly different (P0.05), both with no vegetation degradation showed response relationship, moderate degraded soil bacterial phylotype richness and diversity were the highest, indicating that the degradation for soil bacterial diversity effect may be "moderate disturbance hypothesis". Among them, soil alkali hydrolysable nitrogen and water content are environmental factors that affect the diversity of soil bacteria. Five species of the genus level of different degraded plots for bacterial distribution differences in the door, classes, orders, families and, this will lead to significant changes in some bacterial communities in temperate grassland degradation, but the specific factors that lead to the soil bacterial community structure changes due to the time not in-depth study.
【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S812.2

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