KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 降雨量变化和氮添加对准噶尔荒漠假木贼(Anabasis salsa)-绢蒿(Seriphidium borotalensis)群落和土壤的影响 | |
| Alternative Title | Effects of precipitation change and nitrogen deposition on Anabasis salsa - Seriphidium borotalensis community and soil in Junggar desert |
| 吴珂 | |
| Subtype | 博士 |
| Thesis Advisor | 杨维康 |
| 2020-06-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 理学博士 |
| Keyword | 降雨量变化 氮沉降 荒漠生态系统 植物群落 土壤 Precipitation varities Nitrogen addition Desert Plant community Soil |
| Abstract | 以降水变化和氮沉降增加为代表的全球变化是目前主要环境问题之一， 其对人类生存环境的影响已成为当前全球共同关注的焦点。 作为荒漠生态系统中重要的限制因子， 水分和养分通过对植物生长和土壤养分循环等过程产生影响， 使得生态系统结构和功能发生改变。 目前关于全球变化影响的研究主要关注温带草原生态系统， 在植被稀疏且生产力较低的荒漠生态系统开展的研究相对较少。然而由于干旱少雨、 土壤含氮量低，降雨量变化和氮沉降增加可能会对荒漠生态系统产生较大的生态影响。 基于此， 本研究以准噶尔荒漠假木贼（Anabasis salsa） -绢蒿（Seriphidium borotalensis） 群落和土壤为研究对象， 在 2017 年至 2019 年通过野外控制实验、植被调查、土壤样品采集以及高通量测序分析等方法，研究了荒漠植物群落和土壤对降雨量变化和氮沉降增加的响应， 模拟并揭示了不同降雨梯度和氮沉降条件下植物群落、土壤理化性质、土壤微生物多样性和群落结构，以及土壤酶活性的变化特征， 揭示了降雨量变化和氮沉降增加对荒漠植物群落和土壤的影响。 研究得出如下结论：（1） 降雨量与土壤含水量呈明显的正相关关系，除增雨显著提高了长期干旱土壤的 pH 值与有机质含量外，降雨量变化对其余土壤养分含量无显著影响；加氮导致的土壤酸化可显著降低土壤 pH 值，提高土壤有机质含量以及土壤全氮、速效氮和速效磷含量；降雨和加氮的交互作用对土壤 pH 值无显著影响，显著提高了土壤有机质含量和速效氮含量，但对其余土壤养分含量无显著影响。说明加氮可抵消因降雨量增加而导致的土壤 pH 值升高问题，而二者的叠加效应则促进了土壤有机质的积累，并提高了土壤中的速效氮的含量。（2） 研究区土壤细菌群落中优势类群为拟杆菌门、放线菌门、变形菌门和蓝菌门，土壤 pH 和 TN 是影响土壤微生物群落组成的主要因素。 土壤细菌群落多样性和丰富度随降雨量增加而增加，且极端干旱处理（-60%）与极端増雨处理（+60%）均降低了细菌群落多样性和丰富度。 降雨量变化和氮添加对土壤细菌群落种类组成无显著影响（P>0.05）。氮添加对土壤细菌门水平相对丰度没有显著影响，但不同细菌门对氮添加的响应不同。适当的增雨可通过提高植物生产力促进土壤有机质的积累，此外加氮可有效缓解土壤养分对土壤细菌繁育限制。因此降雨和氮添加存在明显交互作用， 导致土壤细菌群落的多样性和丰富度的提高。（3） 土壤真菌群落中子囊菌门相对丰度最高，是土壤真菌群落中的绝对优势门类。 土壤全钾含量和土壤含水量是影响土壤真菌群落结构的主要因素。 减雨导致真菌多样性指数和丰富度指数增加，而增雨对土壤真菌群落多样性和群落组成影响不显著。氮添加对土壤真菌多样性无显著影响（P>0.05） 。降雨量变化和加氮对土壤真菌多样性和群落组成无显著影响，但囿于有限的研究时间， 不能排除降雨量变化对荒漠生态系统微生物群落组成的长期累积效应。（4） 增雨提高了土壤脲酶、过氧化氢酶和碱性磷酸酶活性，对多酚氧化酶活性无显著影响。 加氮提高了土壤脲酶和碱性磷酸酶活性，对过氧化酶和多酚氧化酶活性无显著影响。不同土层间土壤酶活性差异显著，表层土壤酶活性最高，土壤酶活性随土层加深而逐渐降低。降雨量变化和加氮对土壤酶活性具有一定的交互作用，但不显著，说明这种的影响可能存在滞后效应，还需要开展长期观测揭示不同种类酶活性的变化规律。（5） 植物株高和植物群落盖度随降雨量增加而增加， 植物群落地上生物量随降雨量增加呈先增加后减小趋势， 在增雨 30%处理下地上生物量达到最大值，且增雨明显提高了植物群落丰富度指数和多样性指数。 氮添加对植物群落物种多样性无显著影响， 但显著增加了植物群落株高（P<0.01）、盖度（P<0.05）和地上生物量（P<0.01） 。降雨和氮添加的交互作用对植物群落株高、群落盖度、地上生物量均无显著影响（P>0.05） ， 仅提高了群落均匀度指数。总体而言， 降雨量增加导致植物群落盖度和生物量增高，土壤细菌群落多样性和土壤酶活性增高， 特别是增雨 30%最利于植物生长、土壤养分提高、 土壤细菌群落多样性和土壤酶活性提高。 加氮导致土壤酸化，增加了土壤氮素含量， 提高了植物群落株高、 盖度和地上生物量，但对植物群落 α 多样性、 土壤微生物多样性和种类组成， 以及土壤酶活性无显著影响。本研究通过模拟未来降雨量变化和氮沉降增加对新疆北部荒漠土壤理化性质、土壤微生物、 土壤酶活性与植物群落特征的影响， 初步阐释了干旱半干旱区荒漠生态系统对气候变化的响应机制。 研究结果可为荒漠生态系统的管理与保护提供科学基础， 同时在“干旱区资源可持续利用和应对气候变化”领域具有一定科学指导意义。 |
| Other Abstract | In recent years, the precipitation change and the increase of nitrogen depositioncaused by global changes have become one of the most recognized globalenvironmental problems, and its impact on human living environment has become thefocus of global attention. As the important limiting factors in desert ecosystems, water,nutrients and their availability can affect plant growth, soil characteristics and otherprocesses, thus changing the structure and function of ecosystems. At present, thestudy of global change is mainly focused on the temperate grassland ecosystem, butless on the desert ecosystem with sparse vegetation and low productivity. However,the desert ecosystem is dry and rainless, and the soil nitrogen content is low. Thechange of precipiation and the increase of nitrogen deposition have great ecologicaleffects on desert ecosystem. In this study, the Anabasis salsa - Seriphidiumborotalensis community and soil in Junggar desert was studied by conducting fieldcontrol experiment, vegetation investigation, soil physicochemical properties,microbial and enzyme analysis. Aiming to understand the response of plantcommunities and soil to precipitation change and nitrogen deposition increase, so asto reveals the plant community characteristics, soil physical and chemical properties,soil microbial diversity and community structure and the characteristics of the changeof soil enzyme activity in different precipitation and nitrogen deposition conditions.The experimental results are as follows:(1) There is a significant positive correlation between precipitation and soil watercontent. The change of precipitation has no significant effect on others soil nutrientcontent, except for the increase of precipitation significantly increased the pH valueand soil organic matter content of the long-term dry soil; the acidification caused bynitrogen addition can significantly reduce the pH value of the soil, improve theorganic matter content and the content of total nitrogen, available nitrogen andavailable phosphorus in the soil; the interaction between precipitation and nitrogenaddition had no significant effect on soil pH value, but significantly increased the content of soil organic matter and available nitrogen, and had no significant effect onthe content of other soil nutrients. The results showed that nitrogen addition couldcounteract the increase of soil pH value caused by the increase of precipitation, whilethe superposition effect of the two promoted the accumulation of soil organic matterand the content of available nitrogen in the soil.(2) The dominant groups in soil bacterial community were bacteroidetes,actinomycetes, proteobacteria and cyanobacteria. Soil bacterial diversity and richnessincrease with the increase of precipitation, extreme drought treatment (-60%) andextreme increased precipitation (+60%) also can reduces the community diversity andrichness. Soil pH and TN are the main factors influencing soil microbial communitycomposition. Precipitation changes and nitrogen addition had no significant effect onthe species composition of soil bacterial community. Nitrogen addition had nosignificant effect on the relative abundance of soil bacteriophyta, but differentbacteriophyta had different responses to nitrogen addition. Appropriate increaseprecipitation can promote the accumulation of soil organic matter by increasing plantproductivity, in addition, nitrogen addition can effectively alleviate the limitation ofsoil nutrients on soil bacterial breeding. There was an obvious interaction betweenprecipitation and nitrogen application, which can increase the diversity and richnessof soil bacterial communities.(3) Ascomycetes have the highest relative abundance in soil fungal community andare the absolute dominant group in soil fungal community. Soil total potassiumcontent and soil moisture content are the main factors that affect soil fungalcommunity structure. The decrease of precipitation would increase the diversity indexand richness index of fungi, while the effect of increasing rainfall on soil fungi wasnot significant. Precipitation change and nitrogen addition had no significant effect onsoil fungal diversity and community composition, but the cumulative effect ofprecipitation treatment on microbial community composition in desert ecosystemcannot be excluded because of the limited research time.(4) Precipitation increased the activity of soil urease, catalase and alkalinephosphatase, but had no significant effect on the activity of polyphenol oxidase.Nitrogen addition can increase the activity of soil urease and alkaline phosphatase, buthas no significant effect on the activity of peroxidase and polyphenol oxidase. Therewere significant differences in soil enzyme activity between different soil layers, withthe highest enzyme activity in the surface soil, and the enzyme activity in the soilgradually decreased with the deepening of the soil layer. The effects of precipitationchange and nitrogen addition on enzyme activity in some soils may have a lag effect,long-term experimental observation is needed to study the changes of enzyme activityin different types.(5) The height of community and vegetation coverage was increased with theincrease of the precipitation. The aboveground biomass increased first and thendecreased with the increase of precipitation, and reached the maximum under thetreatment of 30% increased of precipitation. The abundance index and diversity indexof community were increased obviously by increasing precipitation. Nitrogen additionhad no significant effect on vegetation coverage and community diversity in thecommunity, but significantly increased the height and aboveground biomass of plantcommunities. The interaction of precipitation and nitrogen addition had no significanteffect on plant height, community coverage and abovground biomass in thecommunity, but increased the evenness index in the community.The above results show that the increase of precipitation can increase the coverageand biomass of plant communities, increase the diversity of soil bacteria and theactivity of soil enzymes, especially the 30% increase of precipitation is the mostbeneficial to the plants and soil in the study area. Nitrogen addition can cause soilacidification and increase soil nitrogen content, plant community height, coverage andaboveground biomass, but it has no significant effect on α density of plant community,soil microbial diversity and species composition and soil enzyme activity.In this study, we clarified the effects of future precipitation increase or decrease andnitrogen deposition increase on soil physical and chemical properties, soilmicroorganisms, soil enzyme activities and plant community in desert of northernXinjiang, and improved the response mechanism of desert ecosystem in arid andsemi-arid areas to climate change. The research results can provide scientific basis for the management and protection of desert ecosystem, and have certain scientificguiding significance in the field of ‘sustainable utilization of resources in arid areasand coping with climate change’. |
| Subject Area | 生态学 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15454 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 吴珂. 降雨量变化和氮添加对准噶尔荒漠假木贼(Anabasis salsa)-绢蒿(Seriphidium borotalensis)群落和土壤的影响[D]. 北京. 中国科学院大学,2020. |
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