本文關(guān)鍵詞： 刈牧 有機質(zhì) 土壤水分 土壤細菌群落結(jié)構(gòu) 土壤真菌群落結(jié)構(gòu)　出處：《東北師范大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：在全球氣候變化背景下,我國北方草地有機質(zhì)輸入和降水量有潛在增加的可能。放牧是我國北方草地生態(tài)系統(tǒng)主要的管理方式之一。土壤微生物(soil microbes)是土壤中種類最豐富、數(shù)量最龐大的生物類群,在草地生態(tài)系統(tǒng)的養(yǎng)分周轉(zhuǎn)、物質(zhì)循環(huán)和土壤物理結(jié)構(gòu)的保持等方面發(fā)揮重要作用。土壤微生物群落同時受到放牧、有機質(zhì)輸入和降水量的增加等多重因素干擾將呈現(xiàn)何種變化,各干擾因素之間對土壤微生物群落存在怎樣的交互作用。目前,尚無針對這類問題的綜合研究。本研究以盆栽控制實驗的形式開展,選擇松嫩草地優(yōu)勢種植物羊草(Leymus chinensis)及其常見伴生種全葉馬蘭(Kalimeris intergrifolia)和蒙古蒿(Artemisia mongolica)為實驗材料,在松嫩草地生態(tài)研究站開展為期兩年的三因素控制實驗,設(shè)置刈割處理、有機質(zhì)添加處理和水分梯度處理。通過實時熒光定量PCR技術(shù)和HiSeq 2500高通量測序技術(shù)研究土壤真菌和細菌數(shù)量、多樣性以及群落組成,探究刈牧、土壤水分和有機質(zhì)添加對土壤微生物群落的作用規(guī)律及關(guān)鍵影響因子,揭示其作用途徑,有助于深入了解土壤微生物群落對多因素干擾的響應(yīng),為預(yù)測和解釋全球氣候變化條件下我國北方草地土壤微生物群落的潛在變化提供理論依據(jù)。通過研究獲得以下主要結(jié)果和結(jié)論:(1)在本研究的土壤微生物群落中,細菌占優(yōu)勢地位。平均每克干土中細菌基因拷貝數(shù)為9.98×106個,平均每克干土中真菌基因拷貝數(shù)為3.53×104個,真細菌拷貝數(shù)之比平均為2.84×10-3。刈割和水分梯度處理及其及交互作用對土壤細菌數(shù)量有顯著影響。土壤細菌數(shù)量隨水分梯度增加顯著升高,與土壤含水量具有顯著的正相關(guān)關(guān)系;刈割通過提高土壤含水量來增加土壤細菌數(shù)量,土壤含水量是影響土壤細菌數(shù)量變化的主要因素。(2)真菌和細菌的豐富度指數(shù)在實驗處理下變化顯著。刈割降低植物的總生物量進而降低真菌的豐富度。刈割和有機質(zhì)添加及其交互作用對細菌豐富度作用顯著。土壤細菌豐富度指數(shù)與土壤全碳含量具有顯著的正相關(guān)關(guān)系,但土壤全碳含量在實驗處理下并無顯著性變化,刈割增加細菌豐富度這一結(jié)果可能由于刈割改變了植物根系分泌的碳素的種類或質(zhì)量,進而提高細菌豐富度。整體來看,有機質(zhì)添加降低了土壤細菌豐富度,并且削弱了刈割對土壤細菌豐富度的正向作用。(3)水分和刈割對土壤細菌群落組成作用顯著,主要是通過影響放線菌門(Actinobacteria)、綠彎菌門(Chloroflexi)、芽單胞菌門(Gemmatimonadetes)與疣微菌門(Verrucomicrobia)的相對豐度實現(xiàn)的。冗余分析(RDA)的結(jié)果表明,多因子互作實驗處理下,土壤含水量和土壤銨態(tài)氮含量是影響土壤細菌群落組成的主要環(huán)境因子,其中土壤銨態(tài)氮是最重要的影響因子。(4)水分和刈割對土壤真菌部分類群的相對豐度(relative abundance)有顯著影響。刈割通過提高土壤硝態(tài)氮含量增加了接合菌門(Zygomycota)的相對豐度。刈割和水分梯度處理及其交互作用對球囊菌門(Glomeromycota)的相對豐度影響顯著。球囊菌門的相對豐度與土壤含水量具有顯著的負相關(guān)關(guān)系,刈割通過增加土壤含水量來降低球囊菌門的相對豐度。綜上所述,土壤微生物群落對模擬動物采食以及水分變化響應(yīng)敏感,而添加有機質(zhì)在實驗周期內(nèi)對土壤微生物群落沒有顯著影響。土壤水分含量變化直接作用于細菌數(shù)量,動物采食引起土壤含水量變化進而影響土壤細菌數(shù)量。動物采食通過降低植物總生物量來影響真菌的豐富度,而動物采食和有機質(zhì)輸入對土壤細菌豐富度的交互作用還需進一步探究來解釋。本研究證實了水分和養(yǎng)分對微生物群落的調(diào)控作用,土壤含水量和土壤銨態(tài)氮含量是土壤細菌群落組成的主要驅(qū)動因子,土壤銨態(tài)氮含量是最重要的影響因素。降水量變化以及動物采食通過改變土壤水分和速效氮這一途徑,作用于土壤微生物部分類群進而影響土壤微生物的群落組成。土壤細菌群落對實驗處理引起的土壤環(huán)境變化的響應(yīng)比較敏感,而真菌群落雖然處于劣勢地位,對生境變化的抵抗性較強,群落結(jié)構(gòu)相對穩(wěn)定。本研究為解釋和預(yù)測未來松嫩草地土壤微生物群落的潛在變化提供了實驗支持。
[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.

【學(xué)位授予單位】：東北師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S812.2

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