Knowledge Resource Center for Ecological Environment in Arid Area
| 黄河源区冻土和高寒生态系统关系初步研究 | |
| 其他题名 | Preliminary Study on the Relationships between Between Frozen Ground and Alpine Ecosystem in the Source Area of the Yellow River (SAYR) |
| 林琳 | |
| 出版年 | 2012 |
| 学位类型 | 硕士 |
| 导师 | 金会军 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 全气候变化及人类活动对青藏高原冻土及生态稳定性带来威胁。黄河源区气候属高原亚寒带半干旱区。黄河源属生态脆弱区域，在全区变化的背景下其冻土和生态变化显得尤为显著。因此，在黄河源区进行冻土与寒区生态系统的关系研究对理解和保护高寒生态系统和冻土有重要意义。黄河源区的冻土类型错综复杂。综合冻土条件和植被条件，共选择了四个监测场地进行活动层水热过程的监测及植被调查。四个实验区分别是：1查拉坪连续多年冻土区，主要植被类型为高寒沼泽草甸；2扎陵湖不连续多年冻土区，位于扎陵湖西南岸，主要植被为稀疏草甸；3麻多乡岛状多年冻土区，主要植被类型为沼泽化草甸，多种植被类型并存；4鄂陵湖季节冻土区，位于鄂陵湖东北岸，主要植被类型为草原化草甸。\n主要结论如下：\n1、高寒沼泽草甸(查拉坪和麻多乡)是植被覆盖度高和生产力高的植被类型。稀疏草甸的植被虽然盖度和地上生物量低但多度、香农威纳指数和均匀度指数均处于较高水平。\n2、在沼泽草甸地区，土壤养分在垂直剖面的分布也不同。麻多乡沼泽草甸的土壤营养随深度的增加呈现增加或波动的趋势，而查拉坪沼泽草甸的土壤营养随深度的增加呈现减小的趋势。查拉坪的土壤呈弱酸性，麻多乡的呈弱碱性。草原化草甸和稀疏草甸土壤养分大体随深度的增加而减小，pH为弱碱性。土壤0-40 cm的平均土壤全氮、速效氮、全磷、速效磷含量随冻土发育强度的增大而增大。土壤0-40 cm的平均土壤全钾、速效钾含量则是季节冻土区-鄂陵湖地区最高，其它三个地区按照冻土发育程度的减弱依次减小。\n3、黄河源区位于不同冻土类型的植物群落也存在的差异。不同的冻土类型适于特定的植被类型发育。连续多年冻土区发育了高寒沼泽草甸。不连续多年冻土区发育有高寒沼泽草甸、稀疏草甸和黑土滩。季节冻土区发育了草原化草甸。在连续多年冻土区和不连续多年冻土区都发育有高寒沼泽草甸。麻多乡的植被最为复杂，与其岛状多年冻土的分布的复杂性息息相关。冻土分布的复杂性耦合了植被类型的复杂性。在冻土发育好的地方土壤营养也相对丰富，植被发育也好。\n4、在黄河源区，植被退化有其区域性特征。对扎陵湖南岸勒那河汤岔玛的三个植被类型（沼泽草甸，草原化草甸，黑土滩）样地调查分析。沼泽草甸植被盖度、多度及多样性指数显著高于退化的稀疏草甸及黑土滩。稀疏草甸及黑土滩各土壤层养分含量随土壤深度的增加呈下降趋势, pH 值呈上升趋势; 而沼泽化草甸表现出相反的趋势。黑土滩各层pH 值稳定在7.9左右。但是黑土滩没有占绝对优势的种因而黑土滩的均匀度指数最高。黑土滩土壤含水量低，缺乏水相变时给温度变化带来的负反馈。黑土滩的土壤营养并不是各个调查样方中最低的，其形成与放牧和局地的小气候分不开。植被退化过程中，生物多样性有可能增加，即没有明显的建群种导致各种杂草入侵而是生物多样性增加，均匀度指数也增加。因此稳定的，生产力高的群落应该是多样性指数和均匀度指数均适中的群落。 |
| 英文摘要 | Climate change and human activities have brought adverse impacts to permafrost and alpine ecosystems in the Sources Areas of the Yellow River (SAYR). The SAYR is in the zone of an alpine frigid sub-arid climate characterized by long, windy and cold and short, stormy and warm seasons, . There is nowithout absolute frost-free periods, with only cold and warm seasons. The cold season lasts long with strong winds and sand storms. Relatively more abundant precipitation The occurs in the warm season(generally from June to August lasts short with relatively more abundant precipitation. The northeast northwest wind prevails. There are many meteorological hazards in the SAYR. OverallRegionally, the southeastern SAYR is warmer and more moist, while the northwestern part is colder and driery.\nIn order to study the degradation of permafrost and vegetation, four representative experimental plots were chosen for sampling, monitoring and investigations: 1) Alpine paludal meadow at Chalaping in the continuous permafrost zone; 2) Alpine steppes on the southeastern shore of the Gyaring Lake in the patchy permafrost zone; 3) Alpine paludal meadow at Maduo in the discontinuous permafrost zone, and; 4) Alpine steppified meadow on the northeastern shore of the Ngöring Lake in the area of seasonal frozen ground.\nAccording to the investigation and in comparison with the alpine steppe and steppified meadow, The the alpine paludal meadow at Chalaping has high vegetative coverage and primary productivity according to the investigation in comparison with those of the alpine steppe and steppified meadow, showing itsindicating a higher stability and efficiency. While In the meantime, the sparse grassland (steppe?) has a higher values in diversity indexes and evenness indexes.\nIn the paludal meadow, the distribution of soil nutrition varies significantly with depths and at from different sites to site. The soil nutrition contents of soils at Maduo increases or fluctuates with depths, whereas that those at Chalaping decreases with depths. Soils at Chalaping isSoils at Chalaping are slightly acidic, whereas it isthey are slightly alkaline at Maduo. The nutrition contents of the soils in the steppified meadow and steppe decline with depths, and the chemistry of soils display a slightly alkaline budget. The average contents of soil total and available N and P within depths of 0 – 40 cm of soils is may be related to the occurrence of permafrost. However, Tthe soil total and available K of soils are exceptional as they are richer in the areas of seasonally frozen ground..\nVegetation communities differ substantially in various zones of frozen ground in the SAYR. Firstly, specific type of frozen ground tends to be suitable for certain vegetation communitycommunities. For example, the paludal meadow is developed in areas underlain by continuous permafrost in the SAYR. The alpine paludal meadow, steppe and the “Blackened soil spots” are mosaicked in the areas of discontinuous permafrost. In areas affected only by seasonal frozen ground, the alpine meadow is is becoming steppified. The study areas at Maduo have all three fauna of alpine paludal and steppified meadows and steppe. Statistically, Tthis is closely related to the areal extents of permafrost. \nThe result shows that a coupling of permafrost and vegetation community. The soil nutrition content is relatively abundant and the vegetation grows healthier where frozen ground is well developed. These three factors, i.e., permafrost and active layer, vegetation and soil nutrients, interact and are interdependent.\nThe typical ecological features of aA degraded community include:is generally characterized by low levels of vegetative coverage, low primary productivity, poor soil nutrientionnutrition level, and low species diversity. In the SAYR, the “blackened soil spots” is striking as an striking evidence of for land and vegetation degradation.\nOn the southeastern shore of the Gyaring Lake, three experimental plots, steppified meadow (ZLH-1), “Black-soil” meadow (ZLH-2), and swamp paludal meadow (ZLH-3), were chosen to survey study the soil physics, community structures and moisture and thermal processes, and their relationships. The coverage, richness and diversity indices in the paludal meadow are significantly higher than the steppified meadow and the “blacked spots of soils” (severely degraded meadow, with pH values around 7.9). Generally, soil nutrients in the steppified meadow and the “blackened soil spots” decline with depths, while the soil pH rises with depths. However, in the alpine meadow dominated by Carex tibetica, the trends are reversed.\nThe “blackened soil spot” has a higher evenness index, indicating the absence of dominant species in the study plot. The topsoil in the “blackened soil spots” has a higher water permeability, but at depths of 20-30 cm, i.e., the plant root horizons, the water retensionretention rates of soils is are poor and thus harsh for the survival of plants in the arid SAYR. The moisture contents are generally low in the “Blackened soil” , and thus it is vulnerable to dramatic changes in soil and air temperatures. Taking care of the degraded grassland before it gets into the state of “Blacked soil spots” canmay protect the alpine ecosystems more efficiently cost-effectively.?\nHowever, Tthe nutrition level in the “blackened soil spots” is not the lowest, which means that it is not the nutrition that limits the plant growth. The degradation of vegetation may be contributed attributed to over-grazing and inclement microclimate. During the degradation process of vegetation, the biodiversity and evenness of community may even increase, owing to the fact that the lack of dominant species would create more favorable micoenvironments for vthe timely invasion of forbs (weeds). Therefore, a stable and productive community should have moderate biodiversity and evenness indexesindices. When the biodiversity and evenness indexes indices go too high or too lowfluctuate considerably, the community is considered unhealthy. |
| 中文关键词 | 黄河源区 ; 植被退化 ; 冻土 ; 活动层 ; 水热过程 |
| 英文关键词 | the Source Area of the Yellow River (SAYR) vegetation degradation active layer soil moisture frozen ground |
| 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/2XILL650/287103 |
| 推荐引用方式 GB/T 7714 | 林琳. 黄河源区冻土和高寒生态系统关系初步研究[D]. 中国科学院大学,2012. |
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