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| 氮沉降对新疆天山高寒草原植被、土壤及温室气体通量的影响 | |
| 其他题名 | Impacts of Nitrogen Deposition on Vegetation, Soil and Greenhouse Gases Fluxes in Alpine Grasslands of the Tianshan Mountains, Xinjiang |
| 贺桂香 | |
| 出版年 | 2014 |
| 学位类型 | 硕士 |
| 导师 | 刘学军 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 随着人类活动引起的大气活性氮排放的持续增加，全球氮沉降水平也不断升高。当氮沉降水平超过氮素临界负荷时，将导致水体富营养化、森林衰退、土壤酸化和生物多样性下降等了一系列严重的生态问题。草原是陆地表面仅次于森林的绿色覆被层，同时是对氮沉降较为敏感的生态系统，草原氮素循环是全球氮素循环的重要环节。新疆天山中段巴音布鲁克草原是我国最大的干旱区高寒草原之一，对于维持我国草原生态系统的稳定和持续发展发挥着重大作用，因而如何科学评价外源氮输入增加对这一草原生态系统物种多样性、生产力及氮素循环的影响具有十分重要的意义。为此，本文以新疆巴音布鲁克草原为对象，通过设置5个外源氮输入水平（即N0、N1、N3、N9和N15，分别代表氮添加量0、10、30、90和150 kg N ha-1 yr-1，以硝酸铵为氮源），模拟大气氮沉降升高对从高寒草原生产力、物种多样性、土壤理化性质、氮素转化以及温室气体通量的影响，探讨高寒草原对大气氮沉降升高的响应规律。论文的主要研究结果如下： 1. 高寒草原禾本科和非禾本科类植物的物种数变化较小且未受氮沉降水平的显著影响。禾本科的物种数相对稳定，对氮沉降强度的升高无显著响应。非禾本科类的物种数年际间波动较大，对氮沉降相对敏感，随着氮沉降强度的升高，非禾本科类物种数有下降的趋势。氮沉降提高了植被的总盖度、总地上生物量和禾本科植物的盖度、地上生物量，非禾本科类的植被盖度和地上生物量对氮素响应变化趋势与禾本科植物相反。禾本科的植物盖度和地上生物量均高于非禾本科类植物。 2. 与未施肥的样地相比，连续氮添加五年后高寒草原土壤铵态氮和硝态氮随着氮沉降水平升高而显著增加；而土壤有机质、全单、速效氮、含水量和pH值等未随氮沉降水平的提升而发生显著变化。 3．新疆高寒草原的净氨化速率、净硝化速率和净矿化速率随氮沉降水平的升高而显著增加。其中，土壤净硝化速率大于净氨化速率。 4. 氮沉降促进了新疆高寒草原的甲烷吸收强度和生态系统呼吸强度。 |
| 英文摘要 | With rapid increasing emission of reactive nitrogen (N) induced by human activity, atmospheric N deposition and its ecological impacts have been global concerns. Nitrogen deposition can lead to a series of serious ecological problems, such as eutrophication in water bodies, forest decline, soil acidification, biodiversity decline. Nitrogen deposition in grassland ecosystems is likely to play a significant role in global N cycle and indirect greenhouse gas emissions. Alpine grassland of the Tianshan Mountains, Xinjiang plays an important role in maintaining ecosystem stability and sustainability in arid region of central Asia. Therefore scientific assessment of the influence of increased N deposition on the productivity, species abundance, and N cycling of the grassland ecosystem is of great importance. In order to identify the response of plant species, soil physicochemical properties, GHGs emissions and soil nitrogen transformation to elevated N deposition rates, a five-year N deposition experiment (2009-2013) was conducted in Bayinbuluk alpine grassland. Five N deposition rates (N0, N1, N3, N9 and N15, representing 0, 10, 30, 90 and 150 kg ha-1 yr-1, respectively) were selected and applied as ammonium nitrate (NH4NO3) in late May and June each year. The main results are summarized as follows: 1. All the plant species at the studying site were divided into 2 parts: grasses and forbs. After succession of N deposition, species richness of grasses showed increasing trend and a decreasing trend was found for species richness of forbs. But there were no significant changes in plant species richness for both groups under various N deposition rates in past three years (2011-2013). Relative coverage and aboveground biomass of grasses increased with N deposition and experimental year, showing significant relationship between these parameters and N deposition rates. Relative coverage and aboveground of forbs was decreased with N deposition with no significant changes. 2. Soil NH4+-N and NO3--N significantly increased with elevated N deposition. But N deposition did not significantly affect soil moisture content, TN (Total Nitrogen), AN (Available Nitrogen) and SOM (Soil Organic Matter) after five-year N addition. 3. Nitrogen deposition increased net nitrification, ammonification and mineralization rates in the alpine grassland soils. 4. Nitrogen deposition tended to increase CH4 uptake and CO2 emission fluxes compared with those in control (no N addition), although there were no significant differences (P>0.05). |
| 中文关键词 | 高寒草原 ; 氮沉降 ; 物种多样性 ; 土壤理化性质 ; 氮素转化 ; 温室气体 |
| 英文关键词 | alpine grasslands nitrogen deposition species richness soil physicochemical properties nitrogen transformation greenhouse gases |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 环境科学 |
| 来源机构 | 中国科学院新疆生态与地理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287451 |
| 推荐引用方式 GB/T 7714 | 贺桂香. 氮沉降对新疆天山高寒草原植被、土壤及温室气体通量的影响[D]. 中国科学院大学,2014. |
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