Knowledge Resource Center for Ecological Environment in Arid Area
| 额济纳三角洲典型植被群落土壤有机碳动态研究 | |
| 其他题名 | Study on the Soil Organic Carbon Dynamics of the Typical Vegetation Communities in Ejin Banner |
| 苏永红 | |
| 出版年 | 2007 |
| 学位类型 | 博士 |
| 导师 | 冯起 |
| 学位授予单位 | 中国科学院寒区旱区环境与工程研究所 |
| 中文摘要 | 随着全球气候变暖，碳循环研究引起了各国科学家的重视。土壤有机碳作为碳循环的重要组成部分是一个巨大的碳库，据估计有机碳含量是1500 Pg C，大约是大气碳的2倍，土壤碳的微小变化都会对大气CO2浓度起到很大的影响。因此对区域土壤碳动态的研究是碳循环研究的必不可少的环节。位于黑河流域下游的额济纳，气候极端干旱，自然条件极为严酷，生态环境极端脆弱。黑河在穿越河西走廊以后是唯一一条进入该区的河流，河水漫溢处形成了现代荒漠河岸绿洲。而荒漠河乔灌木林则是下游绿洲的主体，其主要任务是维护和改善区域生态环境，在区域的可持续发展中具有重要的作用和地位。但近几十年来，随着气候变暖、黑河流域上中游用水量增加，导致下泄水量减少、河道断流期加长、尾闾湖干涸、地下水位下降、土地沙化、盐渍化加剧，这些势必影响到荒漠绿洲植物根系的呼吸、微生物的群落组成等。在这种情况下，各种群落的土壤碳循环过程也会发生强烈的变化。土壤碳作为生态系统能量和物质循环的重要组成部分，与森林光能利用状况及生物量和生产力有直接的关系。因此，在全球变暖和人类活动影响强烈的背景下，深入了解干旱区荒漠绿洲生态系统土壤碳动态不仅为确定干旱区生态系统碳循环的源/汇属性提供直接的实验支持，对评价干旱区生态系统在全球碳循环中的地位具有重大的价值；同时为维护区域生态环境稳定，制定区域经济的可持续发展等重大的决策方面提供理论依据。\n本文以额济纳绿洲典型植被群落土壤碳为研究对象，应用土壤学原理，通过野外实验与室内分析相结合的方法，对额济纳绿洲土壤碳的贮存环境、地表CO2通量的日变化、季节变化以及不同土壤类型多年碳动态做了分析，同时应用土壤碳循环模型，对额济纳绿洲建群种－胡杨林土壤碳循环做了模拟并对未来50年对气候的响应做了探讨，主要工作和结论如下：\n(1) 在各类植被类型的土壤中挖取了9个剖面，深1m，分析了土壤的机械组成和养分、盐分特征，发现土壤属于碱性沙质土，不利于土壤有机碳的贮存和有机质分解；土壤养分缺乏，盐分表聚现象的土壤类型较多，不利于土壤有机碳的积累；说明研究区土壤有机碳的储存环境差。\n(2) 利用Li-6400-09土壤呼吸室观测了各种典型植被群落的土壤表面CO2通量在不同的季节日变、季节变化趋势。由于受水分和温度的共同作用，胡杨林地地表CO2通量在5、7、9月均为双峰曲线，柽柳林地在5、7、9月均呈单峰曲线，而沙枣在5月和7月呈双峰曲线，而在9月则呈单峰曲线；同时在整个生长季月均地表CO2通量的大小顺序是：7月>8月>6月>9月>5月。从整个区域来看，受水分和植被类型影响土壤呼吸速率值普遍比其它湿润地方的呼吸速率要小。\n(3) 应用土壤呼吸与温度、湿度以及温－湿度的各种模拟关系，拟合了它们之间的关系，当土壤温度是一个独立控制因素时，胡杨和柽柳林地用幂函数（F＝a(T+10)b和F＝a(T-Tmin)b）和指数函数（F= aexp(bT+cT2)）能较好的拟合温度与土壤呼吸之间的关系，各种林地的呼吸速率与土壤深度的关系密切；当湿度成为独立控制因子时，二次方模型对沙枣和柽柳林地土壤呼吸拟合比其它模型更好，而胡杨林地的土壤呼吸用三次方模型拟合的较好；当温度和水分同时成为控制因素时，F＝a+bT+cW+dTW这一线性拟合方程能够更好的反映出胡杨林地和沙枣林地土壤呼吸与土壤温－湿度之间的相关关系，柽柳林地土壤呼吸与温－湿度的相关性用指数模型（LnF＝a+bT+cW+dTW）模拟更为准确。\n(4) 研究了各类土壤的有机碳贮量和密度，认为储量和密度均比较小，土壤有机碳密度最小的土壤是风沙土；根据估算，在近20年来，河岸乔灌木林、河岸灌草林以及荒漠稀疏灌丛均释放了碳，形成有机碳源，只有荒漠稀疏草地蓄积了有机碳，表现为有机碳汇 。\n(5) 运用耦合植被生产系统模型和土壤碳Yasso模型，在参考气候条件下额济纳旗天然胡杨林的土壤碳密度基本维持在9.4-10.5kgC/m2左右；而在全球气候变化的背景下，额济纳旗天然胡杨林的土壤有机碳含量水平将会下降，这主要是由于土壤有机碳的惰性组分的分解速率加快而导致的。 |
| 英文摘要 | With warming of the Earth’s climate, the carbon cycle rose attentions of scientists around the world. As one of the most important portions of carbon cycle, soil organic matter contains a large reservoir of carbon, recently estimated ~1500 Pg C, about twice of the atmospheric CO2-C pool. Small changes in the soil C pool can significantly affect atmospheric CO2 concentrations. So studying the soil C dynamics of regions is necessary to the carbon cycle in the world. Ejin Sub-basin is located in the lower reaches of the Heihe River in the Inner Mongolia Autonomous Region of China belonging to a typical eco-environmental vulnerable zone. The Heihe River flowing through the Hexi Corridor is the only river in this region and formed the modern oasis around the river. Arbor and shrub are the primary parts of the oasis ecosystems and their functions are maintaining and improving the environment, which is significantly important to sustainable development. In recent years, the basin has faced increasingly serious ecological challenges, including the demise of large tracts of vegetation, the disappearance of lakes, a heightened frequency of sand storms, decline of groundwater table, and increasing areas of salina and desert soils. Together, these pose a serious threat to the plant root respiration and microbial compositions of the oasis. In this case, the soil carbon cycle will be changed in oasis ecosystem. As an important part of energy and matter cycle of the ecosystem, the soil C is directly related to the forest light-energy usage, biomass and productivity. Thus, in the background of global warming and stong impact of human activities, the study on the soil C dynamics in detail is significant, which not only can provide a directly experimental proof for the property of the soil as a carbon resource or carbon pool, also can offer important scientific evidences in maintaining eco-environmental development and carrying out sustainable development in the regions.\nBased on the the pedological principle and experiment in this thesis, soil C dynamics of typical arid vegetation has been studied in Ejin, including the storage environment of soil C, the daily, monthly and seasonal changes of soil CO2 fluxes, modeling soil C cycle in the Populu seuphratica forest, and investigation the responses between the carbon cycle and climate in the future 50 years. The main contents and conclusions are shown as the following:\n1.\tSoil samples were collected from the nine soil sections in different kind of typical vegetations to study the constitution, salinity and nutrition distributing features and the relationships between them and soil C. It was concluded that soil in study area belongs to sandy soil, its nutrient components are low, and the phenomenon of salinity congregating on surface developed in most soil. This is disadvantageous to the amassment of soil C.\n2.\tThe changes of soil CO2 efflux in different days and seasons were observation using Li-6400-09 in all kinds of typical soils. Parallel curves of soil CO2 efflux for Populu seuphratica, deloul curves for Tamarix spp. in may, July and September. Parallel curves of soil CO2 efflux for Elaeagnus angustifolia in may and July, but deloul curves in September. In the whole growing season, the order of respiration rate is July>August>June>September>May, and the soil respiration rate in this region is lower than that in humid zone.\n3.\tBased on the existing models, including linear, exponential, combination of exponential and power models, we analyzed the relationship among soil respiration and temperature, moisture and temperature-moisture. When temperature was an independent controlling factor, the models of respiration with an extra parameter (F＝a(T+10)b, F＝a(T-Tmin)b and F= aexp(bT+cT2)）had a better fit than the other power model for the Populu seuphratica and Tamarix spp plots. Whether Populu seuphratica, Tamarix spp or Elaeagnus angustifolia plot, a crucial relationship was found between respiration and temperature in different depth. When soil water-content is an independent controlling factor of soil respiration, the quadratic model produced better fits for the Tamarix spp and Elaeagnus angustifolia plot, but the cubic model fit better for Populu seuphratica. When both soil temperature and moisture are controlling factors, the combined linear model (F＝a+bT+cW+dTW) is more flexibe for Populu seuphratica and Elaeagnus angustifolia plot, and exponential model (LnF＝a+bT+cW+dTW) produced better fits for Tamarix spp plot.\n4.\tThe reserves and density of organic carbon in different soil were studied. We concluded that both the reserves and density of organic carbon in this region are low, and the lowest one of the organic carbon density is the wind-blown sand soil. Based on the estimations during the the last 20 years, the arbor-shrub, shrub-meadow near the river bank and the sparse shrub released the soil C and belong to the soil C resource, but sparse meadow absorbed C and it was a soil C pool.\n5.\tBy coupling the models of vegetation production system and Yasso, the density of Populu seuphratica plot is about 9.4-10.5 kgC/m2 in the average climate conditions of the last 50 years. With the change of global climate, the decomposition rate of the resistant soil organic carbon will get fastly, which will result in the soil organic carbon reserves of the Populu seuphratica decrease. |
| 中文关键词 | 额济纳 ; 典型植被 ; 土壤碳 ; 土壤呼吸 ; 碳循环模型 |
| 英文关键词 | Ejin Oasis Typical vegetation Soil C Soil respiration Carbon cycle model |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286560 |
| 推荐引用方式 GB/T 7714 | 苏永红. 额济纳三角洲典型植被群落土壤有机碳动态研究[D]. 中国科学院寒区旱区环境与工程研究所,2007. |
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