刈牧、水分和有机质添加对草地土壤微生物群落的作用

发布时间：2018-01-26 06:52

本文关键词： 刈牧有机质土壤水分土壤细菌群落结构土壤真菌群落结构　出处：《东北师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：在全球气候变化背景下,我国北方草地有机质输入和降水量有潜在增加的可能。放牧是我国北方草地生态系统主要的管理方式之一。土壤微生物(soil microbes)是土壤中种类最丰富、数量最庞大的生物类群,在草地生态系统的养分周转、物质循环和土壤物理结构的保持等方面发挥重要作用。土壤微生物群落同时受到放牧、有机质输入和降水量的增加等多重因素干扰将呈现何种变化,各干扰因素之间对土壤微生物群落存在怎样的交互作用。目前,尚无针对这类问题的综合研究。本研究以盆栽控制实验的形式开展,选择松嫩草地优势种植物羊草(Leymus chinensis)及其常见伴生种全叶马兰(Kalimeris intergrifolia)和蒙古蒿(Artemisia mongolica)为实验材料,在松嫩草地生态研究站开展为期两年的三因素控制实验,设置刈割处理、有机质添加处理和水分梯度处理。通过实时荧光定量PCR技术和HiSeq 2500高通量测序技术研究土壤真菌和细菌数量、多样性以及群落组成,探究刈牧、土壤水分和有机质添加对土壤微生物群落的作用规律及关键影响因子,揭示其作用途径,有助于深入了解土壤微生物群落对多因素干扰的响应,为预测和解释全球气候变化条件下我国北方草地土壤微生物群落的潜在变化提供理论依据。通过研究获得以下主要结果和结论:(1)在本研究的土壤微生物群落中,细菌占优势地位。平均每克干土中细菌基因拷贝数为9.98×106个,平均每克干土中真菌基因拷贝数为3.53×104个,真细菌拷贝数之比平均为2.84×10-3。刈割和水分梯度处理及其及交互作用对土壤细菌数量有显著影响。土壤细菌数量随水分梯度增加显著升高,与土壤含水量具有显著的正相关关系;刈割通过提高土壤含水量来增加土壤细菌数量,土壤含水量是影响土壤细菌数量变化的主要因素。(2)真菌和细菌的丰富度指数在实验处理下变化显著。刈割降低植物的总生物量进而降低真菌的丰富度。刈割和有机质添加及其交互作用对细菌丰富度作用显著。土壤细菌丰富度指数与土壤全碳含量具有显著的正相关关系,但土壤全碳含量在实验处理下并无显著性变化,刈割增加细菌丰富度这一结果可能由于刈割改变了植物根系分泌的碳素的种类或质量,进而提高细菌丰富度。整体来看,有机质添加降低了土壤细菌丰富度,并且削弱了刈割对土壤细菌丰富度的正向作用。(3)水分和刈割对土壤细菌群落组成作用显著,主要是通过影响放线菌门(Actinobacteria)、绿弯菌门(Chloroflexi)、芽单胞菌门(Gemmatimonadetes)与疣微菌门(Verrucomicrobia)的相对丰度实现的。冗余分析(RDA)的结果表明,多因子互作实验处理下,土壤含水量和土壤铵态氮含量是影响土壤细菌群落组成的主要环境因子,其中土壤铵态氮是最重要的影响因子。(4)水分和刈割对土壤真菌部分类群的相对丰度(relative abundance)有显著影响。刈割通过提高土壤硝态氮含量增加了接合菌门(Zygomycota)的相对丰度。刈割和水分梯度处理及其交互作用对球囊菌门(Glomeromycota)的相对丰度影响显著。球囊菌门的相对丰度与土壤含水量具有显著的负相关关系,刈割通过增加土壤含水量来降低球囊菌门的相对丰度。综上所述,土壤微生物群落对模拟动物采食以及水分变化响应敏感,而添加有机质在实验周期内对土壤微生物群落没有显著影响。土壤水分含量变化直接作用于细菌数量,动物采食引起土壤含水量变化进而影响土壤细菌数量。动物采食通过降低植物总生物量来影响真菌的丰富度,而动物采食和有机质输入对土壤细菌丰富度的交互作用还需进一步探究来解释。本研究证实了水分和养分对微生物群落的调控作用,土壤含水量和土壤铵态氮含量是土壤细菌群落组成的主要驱动因子,土壤铵态氮含量是最重要的影响因素。降水量变化以及动物采食通过改变土壤水分和速效氮这一途径,作用于土壤微生物部分类群进而影响土壤微生物的群落组成。土壤细菌群落对实验处理引起的土壤环境变化的响应比较敏感,而真菌群落虽然处于劣势地位,对生境变化的抵抗性较强,群落结构相对稳定。本研究为解释和预测未来松嫩草地土壤微生物群落的潜在变化提供了实验支持。
[Abstract]:Under the background of global climate change, North China Grassland organic matter input and precipitation have the potential to increase possible. Grazing is one of the main management northern grassland ecosystem in China. Soil microorganism (soil microbes) is the most abundant species in the soil, the largest number of taxa, in nutrient turnover in grassland ecosystem the play an important role in maintaining the material circulation and soil physical structure. The soil microbial community by grazing, organic matter input and precipitation increase of multiple factors such as interference will show what kind of changes on the soil microbial community interaction exists between what the disturbance factors. At present, there is no comprehensive study for this problem in this study. Pot experiments conducted in the form of Leymus chinensis in Songnen grassland, the dominant species selection (Leymus chinensis) and common companion species in the leaf Ma Lan (Kalimeris Intergrifolia Mongolia (Artemisia) and Artemisia mongolica) as experimental materials, three factors of station to carry out a two-year control experiment in the Songnen grassland ecological research, set up cutting processing, adding organic matter processing and moisture gradient processing. By the number of real-time fluorescence quantitative PCR technology and HiSeq 2500 high-throughput sequencing technology to study the soil fungi and bacteria, diversity and the research community, defoliation, soil moisture and organic matter addition on soil microbial community function rule and the key influence factors, reveal its pathway in response to contribute to a deeper understanding of soil microbial communities on the influence of multiple factors, provide a theoretical basis for potential changes in northern China Grassland Soil microbial community and explain the Global Forecast under the condition of climate change. The main results are as follows: (1) through the study of soil microbial community in this study, the dominant bacteria . the average per gram dry soil bacteria in the gene copy number is 9.98 * 106, average per gram of dry soil fungi in gene copy number is 3.53 * 104, the ratio of the average bacterial copy number is 2.84 * 10-3. cutting and processing and moisture gradient and interaction have significant effects on the number of soil bacteria in soil bacteria. The number increased significantly with the increase of moisture gradient, has significant positive correlation with soil moisture; cutting through increasing the soil moisture increased the number of soil bacteria, soil moisture is the main factor affecting the change of the number of soil bacteria. (2) fungal and bacterial richness index changes significantly in the experimental treatment. The total amount of cutting decreased the biological plant and reduce fungal richness. Cutting and organic matter and add a significant interaction effect on bacterial richness. Soil bacteria diversity index and soil total carbon content was significantly positive Close relationship, but the carbon content of the soil in the experimental treatment has no significant change, mowing increases bacterial richness this result may be due to the change of cutting plant root exudation of carbon species or quality, and then improve the bacterial richness. Overall, adding organic matter reduces soil bacterial richness, and weakened the positive effect of cutting on soil bacterial richness. (3) water and cutting on soil bacterial community composition was mainly affected by actinobacteria (Actinobacteria), Chloroflexi (Chloroflexi), gemmatimonadetes (Gemmatimonadetes) and verrucomicrobia (Verrucomicrobia) the relative abundance of redundancy analysis (RDA implementation.) the results show that multi factor interaction experimental treatment, soil moisture and soil ammonium nitrogen content is the main environmental factors affecting the composition of soil bacterial communities, the soil ammonium nitrogen is the most important The impact factor (4). The relative abundance of water and cutting on soil fungi of some species (relative abundance) has a significant impact. Cutting through improving the soil nitrate content increased Zygomycota (Zygomycota). The relative abundance of mowing and water treatments and their interactions on the Glomeromycota (Glomeromycota) the relative abundance of influence significant. The relative abundance of Glomeromycota and soil moisture content has a significant negative correlation between the relative abundance of cutting through the increase of soil moisture to reduce the Glomeromycota. In conclusion, the soil microbial community to simulated animal feed and moisture sensitive response, and the addition of organic matter in the experimental period on soil microbial community is not significant effect. The changes of soil moisture content directly on the number of bacteria, animal feed caused by soil moisture change influences the quantity of soil bacteria in animal feed through. Reducing the total plant biomass to affect fungal richness, and animal feed and organic matter input interaction on soil bacterial richness also needs further research to explain. This study confirmed that water and nutrient regulation of microbial community, soil moisture and soil ammonium nitrogen content is the main driving factor of soil bacteria community, soil ammonium nitrogen is the most important factor. The precipitation changes and animal feed by changing soil water and available nitrogen in this way, effect on Soil Microorganism of some species may affect soil microbial community composition in response to changes of soil environment. The soil bacterial communities on the experimental treatment caused by the more sensitive, and although the fungal communities in the inferior position, the strong resistance to habitat change, community structure is relatively stable. This research is to explain and predict the future in Songnen grassland The potential changes in soil microbial communities provide experimental support.

【学位授予单位】：东北师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S812.2

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