土壤线虫群落对气候及碳输入途径变化的响应

发布时间：2017-12-26 21:28

本文关键词：土壤线虫群落对气候及碳输入途径变化的响应　出处：《河南大学》2016年博士论文　论文类型：学位论文

【摘要】：工业革命以来,人类活动导致的以气候变暖、大气二氧化碳浓度升高、降水格局变化及大气氮沉降等为主要特征的全球变化进程正在对我们赖以生存的陆地生态系统产生重要而深远的影响。作为陆地生态系统最大的有机碳库,土壤碳储量及动态对大气CO2浓度具有重要调控作用。土壤线虫是地下食物网的重要组分,在凋落物分解、营养物质矿化、生物多样性保护及生物地球化学循环过程中发挥重要作用。然而,目前对于全球变化情景下,土壤线虫群落结构及功能的变化及适应依旧缺乏规律性认识。本研究利用控制实验平台,研究气候变暖、降水格局变化、大气氮沉降等全球变化驱动因子及改变植物碳输入途径情景下土壤线虫群落的响应及反馈。研究内容包括四部分,第一部分探讨了增温及增雨对中国北方温带草原土壤线虫群落的影响;第二部分主要研究增雨及氮素添加对中国北方平原弃耕草地土壤线虫群落的影响;第三部分比较了不同施肥梯度对中国北方平原农田生态系统冬小麦样地土壤线虫群落的影响;第四部分主要探讨改变植物碳输入途径对中国北方温带草原土壤线虫群落的影响。取得的主要研究结论如下:(1)在中国北方温带草原生态系统,增温对土壤线虫的影响十分有限,增雨处理显著增加了土壤线虫的多度,显著增加了食细菌性线虫的相对多度,显著降低了杂-捕类线虫的相对多度。在属的水平上,增雨显著增加了小杆属(Rhabditis)、绕线属(Plectus)、垫咽属(Tylencholaimus)和垫刃属(Tylechus)线虫的相对多度,但显著降低了穿咽属(Nygolaimun)、缢咽属(Axonchium)和真矛属线虫(Eudorylaimus)的相对多度。与对照样地相比,增温显著提高了拱唇属(Labronema)和缢咽属(Axonchium)线虫的相对多度,而显著降低了穿咽属线虫(Nygolaimun)的相对多度。(2)在中国北方平原弃耕草地生态系统,增雨显著增加了土壤线虫的多度,但并不影响群落的营养结构;氮添加不改变土壤线虫的多度,但显著降低了土壤线虫属的丰富度,并改变了线虫群落构成,表现为显著增加了食细菌性线虫的相对多度,显著降低了食真菌性及杂-捕类线虫的相对多度。另外氮素添加显著降低了线虫群落的通路指数(CI)及成熟度指数(MI),表明氮素添加处理使土壤食物网向细菌性分解通路偏转,同时食物网的复杂性降低,结构趋向于简单化。(3)在中国北方平原冬小麦样地中,土壤线虫的多度及群落结构随冬小麦生长阶段及施肥量的不同而不同,表现为土壤线虫的多度在冬小麦返青期及拔节期最大,而在实验后期逐渐降低。线虫属的丰富度在冬小麦抽穗期及成熟期较高而在返青期及拔节期较低。土壤线虫的多度随施肥量的增加而增加,但其属的丰富度随施肥量的增加而下降。不同食性类群对施肥量增加的响应不同,表现为食细菌性线虫对施肥量变化不敏感,食真菌性及杂-捕类线虫的相对多度随施肥量增加而减小。植食性线虫在100 kg N ha-1 y-1施肥水平下相对比例达到最大,并随施肥量的进一步增加,其比例逐渐下降,提示合理的施肥方案对农业害虫的防控具有一定现实指导意义。(4)植物根系碳输入途径对土壤线虫群落的影响强于凋落物途径。去除植物显著降低了土壤线虫多度(73.09%)、属的丰富度(17.98%)和植食性及杂-捕类线虫的相对多度,但是增加了食细菌性线虫的相对多度。凋落物添加显著增加了土壤线虫的多度(37.88%),但不影响其群落结构。凋落物去除显著降低了土壤线虫属的丰富度(9.39%)。土壤线虫多度与土壤养分(SOC,TN,MBC,MBN)间显著的正相关关系表明,土壤线虫多度的变化主要受土壤养分含量的影响,而不同食性类群与土壤pH及NO3--N浓度之间的相关分析结果显示,土壤线虫群落结构的变化主要与土壤的理化环境有关。另外,本研究发现,凋落物对土壤线虫群落的影响受植物的调控,两者的交互作用比单一因素作用更为复杂。(5)土壤呼吸与土壤线虫的多度及属的丰富度间存在显著的正相关关系,提示在今后关于土壤碳储量评估及碳动态预测研究中,应加入对土壤动物的考量。
[Abstract]:Since the industrial revolution, the global change process characterized by climate warming, atmospheric CO2 concentration, precipitation pattern change and atmospheric nitrogen deposition has been significantly and profoundly influenced by the human activities. As the largest organic carbon pool in the terrestrial ecosystem, the soil carbon reserves and dynamics have an important control effect on the atmospheric CO2 concentration. Soil nematodes are important components of underground food web. They play an important role in litter decomposition, nutrient mineralization, biodiversity conservation and biogeochemical cycle. However, the changes and adaptation of soil nematode community structure and function are still lack of regularity under the situation of global change. In this study, we use the control experiment platform to study the global warming driving factors such as climate warming, precipitation pattern change, atmospheric nitrogen deposition and the response and feedback of soil nematode communities under the circumstances of plant carbon input. The study includes four parts, the first part discusses the effects of warming and precipitation of Chinese northern temperate grassland soil nematode community; effects on the northern plains Chinese abandoned grassland soil nematode communities in the second main part of rainfall and nitrogen; the third part compares the different fertilization gradient effects on soil nematode communities in North Plain Chinese the ecological system of winter wheat plots; the fourth part mainly discusses the influence of the change of plant carbon inputs of Chinese northern temperate grassland soil nematode community. The main conclusions are as follows: (1) China in northern temperate grassland ecosystem, effects of warming on soil nematode is very limited, rainfall treatments significantly increased soil nematode abundance, significantly increased bacterial feeding nematode abundance, significantly reduced the impurities, the relative abundance of nematode trapping. In the genus level, rainfall increased Rhabditis (Rhabditis), (Plectus), a winding pad (Tylencholaimus) and swallow genus tylenchus nematodes (Tylechus) relative abundance, but significantly reduced the wear of the pharynx (Nygolaimun), (Axonchium) and a pharyngeal constriction really spear nematodes (Eudorylaimus) relative abundance. Compared with the control plots, warming significantly increased the lip arch is (Labronema) and (Axonchium) a pharyngeal constriction nematode abundance, and significantly reduced the wear pharyngeal nematodes (Nygolaimun) relative abundance. (2) in the Northern Plains grassland ecosystem Chinese abandoned, rainfall increased soil nematode abundance, but does not affect the nutrition structure of the communities; nitrogen addition does not change the soil nematode abundance, but significantly reduced the richness of soil nematodes of the genus and changed the nematode community composition, showed significantly increased food the relative abundance of bacterial nematodes, fungal feeding significantly reduced and impurities, the relative abundance of nematode trapping. In addition, nitrogen addition significantly decreased the CI and MI of the nematode communities, indicating that nitrogen addition reduced the soil food web to bacterial decomposition pathways, and the complexity of the food web decreased and the structure tended to be simplified. (3) the winter wheat in the northern plains Chinese plots, soil nematode abundance and community structure with the growth stage of winter wheat and fertilization is different, as the soil nematode abundance in winter wheat at the jointing stage and the largest, and gradually decreased in the later stage of the experiment. Abundance of nematode genera in higher winter wheat heading and maturity in regreening stage and jointing stage is low. The abundance of soil nematodes increased as the amount of fertilizer increased, but the abundance of the genus was decreased with the increase of the amount of fertilizer. The response of different feeding groups to the increase of fertilizer amount is different. It shows that bacterial eating nematodes are not sensitive to the amount of fertilizer, and the relative abundance of fungi and nematodes is reduced with the increase of fertilizer amount. The relative proportion of phytophagous nematodes reached the maximum at 100 kg N HA-1 Y-1 fertilization level, and the proportion gradually decreased with the further increase of fertilizer amount. This indicates that reasonable fertilization plan has practical guiding significance for the prevention and control of agricultural pests. (4) the effect of plant root carbon input on soil nematode community was stronger than that of litter path. Removal of plants significantly reduced soil nematode abundance (73.09%), genera richness (17.98%), and relative abundance of herbivorous and heterotrapping nematodes, but increased the relative abundance of bacterial nematodes. Litter added significantly increased the degree of soil nematode (37.88%), but did not affect its community structure. Litter removal significantly reduced the richness of soil nematode (9.39%). Soil nematode abundance and soil nutrients (SOC, TN, MBC, MBN) showed significant positive correlation, the effects of soil nematode abundance is mainly affected by soil nutrient content, and the correlation analysis between different feeding taxa and soil pH and NO3--N concentrations showed that the soil nematode community structure is mainly about physical and chemical environment in soil. In addition, it was found that the effects of litter on soil nematode community were regulated by plants, and the interaction between them was more complex than that of a single factor. (5) there was a significant positive correlation between soil respiration and soil abundance and richness of soil nematodes, suggesting that soil fauna should be considered in future research on soil carbon storage assessment and carbon dynamics prediction.
【学位授予单位】：河南大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S154.386

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