氮添加对内蒙古东部草甸草原碳源汇特征的影响

发布时间：2018-01-31 07:10

本文关键词： 氮添加碳循环碳源汇碳循环模式　出处：《内蒙古大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着全球氮沉降、施肥活动的增加,外源氮素添加对于碳循环的影响也逐渐成为研究热点。大多数研究只关注氮素影响的某一方面,缺乏氮添加与生态系统关系的系统分析。本文通过对内蒙古呼伦贝尔草甸草原不同水平氮添加控制实验中碳循环各组分的测定,分析草甸草原碳循环各个环节的特征并构建碳循环模式,揭示N添加对于碳循环的影响以及生态系统碳源汇的问题。这一问题有助于深入了解全球气候变化中外源氮增加后对该生态系统的影响,对以增加草甸草原生态系统碳汇为基础的草地可持续性管理也有一定的应用价值。主要研究结果如下：1.氮添加会显著提高生态系统地上净初级生产力,但对地下生产力的影响不显著；2.N添加对于0-100cm土层整体及各层土壤有机碳含量均没有显著影响；但土壤碳的积累是一个长期的过程,短时间的氮添加不能很快增加土壤有机碳的含量；3.N添加对于枯落物剩余量与分解量均没有显著影响,但N添加具有提高枯落物产量和分解量的趋势；4.土壤呼吸对N添加浓度的响应不同：高氮处理显著促进了自养呼吸,但却显著抑制了异养呼吸；低氮处理显著抑制了自养呼吸,对于异养呼吸的影响并不显著；5.土壤呼吸与土壤温度之间关系密切,而土壤呼吸温度敏感性对于N添加不敏感；土壤呼吸对N素添加的响应程度与土壤湿度有关,土壤湿度越大,土壤呼吸对于施肥的响应程度越高；6.内蒙古东部草甸草原生态系统在生长季表现为净碳汇,每年生长季净吸收130gC/m2；7.N的添加有利于草甸草原生态系统碳汇的增加,主要通过促进碳吸收和减少碳排放两种方式实现；高氮处理提高了净初级生产力,但也促进了生态系统碳排放,低氮处理对净初级生产力影响较小,但减少了生态系统碳排放。8.构建了草甸草原碳循环基本模式及不同N添加后的碳循环模式。
[Abstract]:With the global nitrogen deposition and the increase of fertilization activities, the effect of exogenous nitrogen addition on carbon cycle has gradually become a hot topic. Most studies only focus on one aspect of nitrogen effect. Based on the systematic analysis of the relationship between nitrogen deficiency and ecosystem, the carbon cycle components of Hulunbeir meadow in Inner Mongolia were determined in the experiment of nitrogen supplementation control at different levels. The characteristics of each link of carbon cycle in meadow grassland were analyzed and the carbon cycle model was constructed. To reveal the effects of N addition on the carbon cycle and the carbon source and sink of the ecosystem, which is helpful to understand the effects of exogenous nitrogen on the ecosystem in the global climate change. It also has some application value to the sustainable management of grassland based on increasing carbon sink of meadow grassland ecosystem. The main results are as follows: 1. Nitrogen addition can significantly improve the net primary productivity of the ecosystem above ground. But the influence on underground productivity is not significant. 2.N addition had no significant effect on soil organic carbon content in 0-100 cm soil layer. However, the accumulation of soil carbon is a long-term process, and the content of soil organic carbon can not be increased quickly by adding nitrogen for a short time. 3.N addition had no significant effect on litter residue and decomposition, but N addition had the tendency of increasing litter yield and decomposition. 4. The responses of soil respiration to N addition concentration were different: high nitrogen treatment significantly promoted autotrophic respiration, but significantly inhibited heterotrophic respiration; Low nitrogen treatment significantly inhibited autotrophic respiration, but had no significant effect on heterotrophic respiration. 5.The relationship between soil respiration and soil temperature is close, but the sensitivity of soil respiration temperature is not sensitive to N addition. The response of soil respiration to N addition was related to soil moisture. The higher the soil moisture, the higher the response of soil respiration to fertilization. 6. The grassland ecosystem in eastern Inner Mongolia shows a net carbon sink in the growing season, with a net absorption of 130 g C / m ~ (2) per year. 7.The addition of N is beneficial to the increase of carbon sink in meadow grassland ecosystem, mainly through promoting carbon absorption and reducing carbon emission. High nitrogen treatment increased net primary productivity, but also enhanced ecosystem carbon emissions, and low nitrogen treatment had little effect on net primary productivity. However, the carbon emission from ecosystem was reduced. 8. The basic model of carbon cycle in meadow steppe and the carbon cycle model after different N addition were constructed.
【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S812

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