不同氮素化合物的添加对额尔古纳草原土壤线虫群落的影响

发布时间：2018-03-15 23:02

本文选题：氮沉降　切入点：氮素化合物　出处：《沈阳师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着工业革命的发展,人类的活动对地球环境的影响越来越严重。工厂废气的排放,化石燃料的燃烧以及化肥的过度使用,使得大气中的氮素化合物日趋上升。大气中的氮素通过干沉降和湿沉降两种方式输入到陆地生态系统中,这给陆地生态系统带来大量的氮素输入,氮素的输入对陆地生态系统结构和功能带来显著的影响。氮素富集对地上植物群落结构的影响已经做了大量的研究,但是对地下生物群落对氮沉降的响应及其机理研究相对偏少。土壤是陆生态系统生物多样性最丰富的亚系统,土壤动物对生态系统有机质的分解、养分循环起着重要作用,其与土壤微生物、地上植物构成的食物链调控着生态系统结构和功能。土壤线虫是陆地上多度最高的多细胞生物,适应环境能力强,因此线虫可以生活在任何的地方,其对环境干扰响应敏感,是典型的指示生物。为此,我们利用中国科学院内蒙古额尔古纳不同氮素化合物添加实验平台,研究土壤线虫群落对草原不同利用方式(刈割与不刈割)、不同氮素化合物添加的响应方式及其机理。相对于其他氮素添加实验不同的是,本实验的创新点是添加五种不同的氮素化合物,这与大气中氮素化合物种类更为贴近,更能真实的反应实际情况下氮沉降对陆地生态系统中土壤动物的影响。不同的氮素化合物对土壤线虫的影响是不同的,随着氮素速率的增加,土壤线虫的多度有明显的升高,而多样性却显著降低,这意味着,随着氮素的添加导致土壤线虫物种的丢失。而通过分析土壤线虫的成熟度指数(MI)以及优势属集中程度指数(DOM)这两个指数来看,随着氮素的添加,土壤线虫的成熟度降低,优势属的集中程度增多,表明大量的氮素输入导致土壤线虫群落退化。通过土壤线虫群落不同功能团的分析发现,不同的氮素化合物对不同的功能团的影响不同:其中,食细菌和食真菌两类线虫对氮素化合物的添加是呈上升趋势;相反,随着氮素化合物速率的增加,捕食杂食类线虫和植物寄生类线虫的数量是降低的。研究发现氮素添加降低了食真菌线虫与食细菌线虫的比例(F/B),表明氮素添加后,土壤养分循环更多的通过细菌途径进行。本研究对预测全球变化背景下草原土壤线虫多样性的响应具有重要的意义。
[Abstract]:With the development of the industrial revolution, the impact of human activities on the earth's environment has become more and more serious. The emissions from factories, the burning of fossil fuels, and the overuse of chemical fertilizers, Nitrogen compounds in the atmosphere are rising day by day. Nitrogen in the atmosphere is fed into the terrestrial ecosystem by both dry and wet deposition, which brings a lot of nitrogen input to the terrestrial ecosystem. Nitrogen input has a significant impact on the structure and function of terrestrial ecosystems. The effects of nitrogen enrichment on the community structure of aboveground plants have been studied extensively. However, there are few studies on the response and mechanism of underground biota to nitrogen deposition. Soil is the most abundant sub-system of terrestrial ecosystem biodiversity. Soil animals play an important role in the decomposition of organic matter and nutrient cycling in ecosystem. The structure and function of the ecosystem are regulated by the food chain of soil microbes and aboveground plants. The soil nematodes are the most abundant multicellular organisms on the land and have a strong ability to adapt to the environment, so that nematodes can live anywhere. It is sensitive to environmental disturbance and is a typical indicator organism. To this end, we use different nitrogen compounds in Erguna, Inner Mongolia, Chinese Academy of Sciences to add experimental platform. The responses and mechanisms of soil nematode communities to different utilization patterns (mowing and no cutting, different nitrogen compounds addition) in grassland were studied. Compared with other nitrogen supplementation experiments, the response of soil nematode community to grassland was different from that of other nitrogen supplementation experiments. The innovation of this experiment is the addition of five different nitrogen compounds, which is closer to the type of nitrogen compounds in the atmosphere. Different nitrogen compounds have different effects on soil nematodes, and the abundance of soil nematodes increases with the increase of nitrogen rate. But the diversity decreased significantly, which means that the loss of soil nematode species was due to the addition of nitrogen. By analyzing the maturity index (MII) and the dominant genus concentration index (DOM) of soil nematodes, With the addition of nitrogen, the maturity of soil nematodes decreased, and the concentration of dominant genera increased, indicating that a large amount of nitrogen input led to the degradation of soil nematode communities. The effects of different nitrogen compounds on different functional groups were different: among them, the addition of nitrogen compounds by two kinds of nematodes, bacteria and fungi, showed an upward trend; on the contrary, with the increase of the rate of nitrogen compounds, The number of predatory nematodes and plant parasitic nematode decreased. The study found that nitrogen addition reduced the ratio of fungal nematode to bacteriophagous nematode, indicating that the addition of nitrogen decreased the ratio of fungous nematode to bacterial nematode. Soil nutrient cycling is more carried out through bacterial pathway. This study is of great significance to predict the response of soil nematode diversity in steppe under the background of global change.
【学位授予单位】：沈阳师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S812.2

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