氮沉降背景下枯落物对松嫩草地土壤线虫群落特征的作用

发布时间：2018-06-19 03:49

本文选题：土壤线虫 + 施氮　；参考：《东北师范大学》2016年硕士论文

【摘要】：土壤线虫(soil nematode)在土壤食物网中占多个营养级,对于维持土壤生态系统稳定、有机质分解、植物营养矿化及养分循环过程具有重要意义。氮沉降(nitrogen deposition)现象日益严重,对线虫群落特征以及生态功能造成很大影响。草地枯落物(litter)是地上植物生产力进入分解者亚系统的主要途径与关键环节,枯落物分解后向土壤中输入碳、氮、磷等营养元素。施氮和枯落物均能够通过改变植物群落、土壤理化性质和土壤环境进一步影响土壤线虫群落。目前,关于氮沉降背景下不同枯落物水平对线虫群落的调节作用还缺少相关研究。本论文以松嫩草甸草原为研究对象,通过施氮和添加、去除枯落物的控制实验,研究氮沉降背景下枯落物对土壤线虫群落特征以及土壤理化性质和植物群落特征的影响,揭示了氮沉降背景下枯落物通过改变植物群落和土壤环境条件调节线虫群落的作用机制。获得如下主要研究结论:(1)本实验发现松嫩草甸草原的线虫个体平均密度为261条/100 g干土。隶属于31科,54个属。其中优势属为垫咽属和拟丽突属;常见属包括巴兹尔属、矮化属和短体属等18个属;稀有属包括具脊垫刃属、叉针属和盘旋属等34个属。(2)施氮和枯落物对线虫丰富度无显著影响。施氮和枯落物处理对土壤p H和总氮含量都无显著影响,但线虫丰富度随土壤p H升高而降低,随土壤总氮含量升高而增加。土壤p H主要通过减少丝尾垫刃属和盘咽属多度降低线虫丰富度,土壤总氮通过增加盘旋属和棱咽属线虫多度增加线虫丰富度。(3)施氮对线虫的作用受枯落物水平的影响。在2倍枯落物水平上施氮能够显著降低线虫多度、多样性以及成熟度指数,而在去除和1倍枯落物水平上施氮无显著作用。施氮能够直接减少线虫多度,也能够通过提高土壤硝氮含量和植物地上生物量增加线虫多度和多样性。(4)施氮能够改变枯落物对线虫的调节作用。在不施氮情况下,线虫多度随枯落物增加而升高,多样性和成熟度指数随枯落物水平无显著变化;而在施氮情况下,线虫多度不受枯落物影响,多样性和成熟度指数随枯落物增加而降低。枯落物通过提高土壤含水量增加线虫多度,可以直接减少线虫多样性,也能够通过抑制优势植物生长降低线虫多样性。(5)施氮和枯落物对线虫群落的影响具有交互作用。随枯落物的增加施氮对线虫的不利影响增强,并且施氮后增加枯落物也不利于维持线虫群落的群落结构和稳定性。表明减少枯落物能够减弱氮沉降对土壤线虫的不利影响,并且在氮沉降背景下,放牧、割草等适度的草地利用可以通过减少枯落物来维持草地生态系统的结构和功能的稳定性。综上所述,本研究阐明了施氮和枯落物影响土壤线虫群落特征的作用规律,揭示了施氮和枯落物通过改变土壤环境和植物群落调节线虫群落的内在机制。本研究结果表明,线虫多度与土壤含水量和硝态氮含量正相关,线虫多样性与土壤总氮和植物地上生物量正相关,施氮能够通过提高土壤硝氮含量和植物地上生物量增加线虫多度和多样性,枯落物能够通过抑制优势植物生长降低线虫多样性,该研究结果丰富了生物多样性理论;在氮沉降背景下,增加枯落物能够降低线虫群落的稳定性,表明放牧、割草等适度的草地利用可以通过减少枯落物来维持草地生态系统的结构和功能的稳定性,加深关于草地生态系统结构和功能对全球变化和人类干扰响应的理解。
[Abstract]:Soil nematode (soil nematode), which accounts for many nutritional levels in the soil food network, is of great significance for maintaining soil ecosystem stability, organic matter decomposition, plant nutrition mineralization and nutrient cycling. The nitrogen deposition (nitrogen deposition) phenomenon is increasingly serious, which has a great influence on the characteristics of the colony and the ecological function of the nematode. Litter is the main approach and key link in the subsystem of plant productivity into the decomposer. After litter decomposition, the nutrient elements such as carbon, nitrogen and phosphorus are input into the soil. Nitrogen application and litter can all affect soil nematode communities by changing plant communities, soil physical and chemical properties and soil environment. In this paper, the effects of litter on the characteristics of soil nematode community, the physical and chemical properties of soil soil and the characteristics of the plant community were studied in this paper. The main conclusions are as follows: (1) the average density of the nematode in the Songnen meadow grassland is 261 /100 g dry soil, which belongs to 31 families and 54 genera. The dominant genus is the genus hypopharyne and parinus. 18 genera including Basil M, dwarf and short body; rare genera including 34 genera with ridges, spunneedles and circling genera. (2) nitrogen application and litter have no significant effects on the abundance of nematodes. Nitrogen application and litter treatment have no significant effects on soil P H and total nitrogen content, but the nematode abundance decreases with soil P H, with soil Total nitrogen content increased. Soil P H mainly reduced nematode richness by reducing the genera of silk tail pads and hypopharynx. Total soil nitrogen increased nematode richness by increasing circling and nematode. (3) the effect of Nitrogen Application on nematodes was affected by the level of litter. Nitrogen application at 2 times of litter could significantly reduce nematodes. Diversity, diversity and maturity index have no significant effect on removal of nitrogen and 1 times the level of litter. Nitrogen application can directly reduce nematode abundance and increase the diversity and diversity of nematodes by increasing soil nitrogen and aboveground biomass. (4) nitrogen application can change the regulation of litter to nematodes. The abundance of nematodes increased with the increase of litter, and the diversity and maturity index did not change significantly with the level of litter. In the case of nitrogen application, the abundance of nematodes was not affected by the litter, and the diversity and maturity index decreased with the increase of litter. Diversity, can also reduce the diversity of nematodes by inhibiting the growth of dominant plants. (5) nitrogen application and litter have interaction effects on the nematode community. With the increase of nitrogen application, the adverse effects of nitrogen on nematodes are enhanced, and the increase of litter after nitrogen application is not conducive to the maintenance of the community structure and stability of the nematode community. It can reduce the adverse effects of nitrogen deposition on soil nematodes, and moderate grassland utilization, such as grazing and mowing, can maintain the stability of the structure and function of the grassland ecosystem by reducing the litter in the background of nitrogen deposition. In this study, the effects of nitrogen and litter on the characteristics of soil nematode communities are clarified. The results showed that the diversity of nematodes was positively related to soil water content and nitrate content, and the diversity of nematodes was positively related to soil total nitrogen and aboveground biomass, and nitrogen application could increase soil nitrogen and plant soil by increasing soil nitrogen and plant land. The biomass increases the diversity and diversity of nematodes. The litter can reduce the diversity of nematodes by inhibiting the growth of the dominant plants. The results enrich the theory of biodiversity. In the background of nitrogen deposition, the increase of litter can reduce the stability of the nematode community, indicating that grazing, mowing and other appropriate grassland utilization can reduce the litter size. To maintain the stability of the structure and function of the grassland ecosystem and to deepen the understanding of the structure and function of the grassland ecosystem on the global change and the response to human interference.
【学位授予单位】：东北师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S812.2

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