Knowledge Resource Center for Ecological Environment in Arid Area
| 毛乌素沙地植被风蚀斑块的环境特征及植物适应性 | |
| 其他题名 | Environment characteristics and plants’ adaptive strategies in wind erosion patches of the vegetation communities of Mu Us Sandland, semiarid area in Northwest China |
| 张曙东 | |
| 出版年 | 2018 |
| 学位类型 | 硕士 |
| 导师 | 黄振英 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 毛乌素沙地是我国重要的生态过渡带和典型的生态脆弱区。近年来，由于人类活动干扰的加剧，导致毛乌素沙地植被退化。沙地植被风蚀斑块是沙地生态系统中，由于人为干扰导致群落中植被缺失造成地表裸露，并在强风作用下发展扩大而产生的植被空白斑块。研究沙地植被风蚀斑块的发生和发展过程及其对植被的影响，对于深入理解我国北方沙地植被稳定性与环境因子间的相互关系具有理论意义，也能够为沙区荒漠化防治与植被修复的生产实践提供科学支撑。因此，本文围绕毛乌素沙地植被风蚀斑块的发生发展过程，以风因子为主要影响因素，通过野外调查监测、野外控制实验与实验室实验相结合的方法，在个体和群落尺度上，开展以下研究：（1）沙地植被风蚀斑块内非生物环境因子动态变化特征及其与风蚀斑块大小的关系；（2）沙地植被风蚀斑块内种苗库(土壤种子库和幼苗库)分布格局及其影响因子；（3）沙地植被的群落结构和功能对风因子的响应与适应；（4）沙地主要植物种对风蚀斑块内特殊的环境条件(风速增强、表层土壤流失)的适应机制。主要研究结果如下：（1）沙地植被风蚀斑块内外非生物环境因子存在明显差异，这种差异受斑块大小和土壤深度影响，并在时间上存在动态变化。在植被风蚀斑块内部，土壤温度高于风蚀斑块外部，在0-5 cm的表层土壤表现最为明显，并随着土壤深度的增加而相对减弱；与斑块边缘相比，斑块内部的土壤速效钾、碱解氮和有机碳含量均显著下降。沙地植被风蚀斑块内外的环境差异随着风蚀斑块面积的增大而增大。（2）斑块大小、取样时间和取样位置显著影响了植被风蚀斑块中种苗库（土壤种子库与幼苗库）密度。土壤种子库的种子密度与数量存在季节性的动态变化，其变化幅度随着土壤深度的增加而下降。受主风向的影响，土壤种子库在不同大小斑块中的分布格局存在差异，幼苗库的分布与土壤种子库相对应。斑块内幼苗的更新受微环境制约，部分一年生植物能够完成生活史，但多年生植物幼苗无法正常更新。（3）优势植物油蒿（Artemisia ordosica）群落在不同强度风速下都表现出了较强的稳定性，风速的改变在短期尺度内对群落中的物种数、重要值以及群落中的物种多样性指数（Shannon-Weiner指数、Simpson指数和Pielon指数）均无显著影响。随着风速增加，群落中两个优势种油蒿和羊柴（Hedysarum leave）的生长受到一定抑制（株高、冠幅和密度下降）；而群落中12种主要伴生种中，仅有4种植物，苦荬菜（Ixeris chinensis），赖草（Leymus secalinus），虫实（Corispermum spp.）和早熟禾（Poa sphondylodes）的生长（株高、密度下降）受到不同风强处理的显著影响；建群种为群落的抗风能力贡献了主要作用。（4）风蚀造成的根系暴露对优势植物种油蒿和羊柴的生长产生负面影响（营养生长减缓、植株含水量下降）；随着根系暴露程度的增加，油蒿存活率显著下降。对油蒿、中间锦鸡儿（Caragana intermedia），刺沙蓬（Salsola ruthenica）和沙蓬（Agriophyllum squarrosum）4个物种的野外控制实验表明，在面对风因子胁迫时，植物会通过减小自身承载压力（降低株高、减少冠幅、减少生物量、减小叶片长度等）、增加自身抗性（基径增大，根长度增加）或改变自身机械性状进行响应，但不同植物种在响应风因子时所采取的适应策略存在高度的种间特异性。综上所述，沙地植被风蚀斑块的形成往往会改变斑块内环境条件，降低土壤种子库密度和幼苗存活，从而阻碍斑块内幼苗的正常更新。风蚀导致的根系暴露还会直接影响到植物的生长与存活。毛乌素沙地植被主要植物种应对风因子的策略具有高度的种间特异性，在群落层次上优势的半灌木物种表现出较强的稳定性。因而，在沙地植被风蚀斑块的植被恢复过程中，需要采取针对性的措施（如补充土壤养分、建立人工沙障等）改善斑块内的环境条件，补充土壤种子库，选择适应性强的植物种重构植被群落。 |
| 英文摘要 | Mu Us Sandland is an important ecotone located in the desert zone of Northern China, which has an unstable and fragile ecosystem. Wind erosion patches in sandland vegetation communities are created by the anthropogenic interference and will expand with soil erosion. With the frequent interruptions of human activity recent years in Mu Us Sandland, vegetation degradation occurred in some areas that have good vegetation restoration.The study about the influences of development process of wind erosion patches in sandland vegetation communities on sandland vegetation growth is critical for understanding the relationship between vegetation stability and environment factors of the Sandland of Northern China, and will provide scientific support for desertification control and vegetation restoration of this region. Thus, this study focused on the occurrence and development process of wind erosion patches in sandland vegetation communities during the vegetation degeneration process of Mu Us Sandland, and considered wind as the main environment factor, through field monitoring and control experiments, in the individual and community scale, studied the following questions: (1) The differences of abiotic environmental factors between the inside and the outside of the wind erosion patches in sandland vegetation communities of Northern China and the size effect on them. (2) The distribution pattern of soil seed bank and seedling bank in the wind erosion patches in sandland vegetation communities of Northern China, and its influence factor. (3) The community structure and function of sandy vegetation in response to wind factor. (4) The adaptive strategies of main plant species in the Mu Us Sandland facing harsh environmental conditions (wind speed enhancement and surface soil loss) in the wind erosion patches. The main conclusion as following:(1) The differences of abiotic environmental factors between the inside and the outside of the wind erosion patches in sandland vegetation communities were existed. Soil temperature was higher than outside patches compared the soil in the patches. The difference of soil temperature in the patch was affected by the patch size and soil depth, especially in the surface soil of 0-5 cm depth. Inside the patches, the content of the soil available nutrient decreased with the increase of the size of the wind erosion patches. The content of the soil available nutrient outside the patches affected by the soil depth, and decreased with the increase of soil depth. With the increase of the patch size, differences of environment factors inside and outside of the patch increased.(2) The distribution pattern of soil seed bank and seedling bank in the wind erosion patches in sandland vegetation communities was affected by the patch size, time and location significantly. Affected by wind direction, seed densities and numbers of soil seed bank and and the maximum point of seed densities varied in the time scale and decreased with the increase of the soil depth. The distribution of seedling bank was corresponding to the soil seed bank, and varied with the change of location and seasons. In the patches, part of the annual plants completed their life history, but seedlings of perennial plants could not live through the winter.(3) The communities of Artemisia ordosica barely affected by the wind treatment. The change of wind speed had no significant effect on the number of species, important values and diversities in the community in a short term. However, constructive species and main accompanying species in the community would be affected slightly by the wind stress, with the decrease of height and crown width, and changes of plant densities in the community by the increasing wind influences. Only 4 of 12 main accompanying species in the community (Ixeris chinensis, Leymus secalinu, Corispermum spp. and Poa sphondylodes) had been affected by the increasing wind velocity in plant growth. The constructive species play a vital part in increasing the resistant abilities of community against wind.(4) Wind erosion would influence the growth of plants, the results of artificial denudation experiment showed that root exposure had a negative effect on the growth of Artemisia ordosica and Hedysarum leave which is the dominated species in Mu Us Sandland. With the increase of denudation, survival rate of Artemisia ordosica decreased. The study of Artemisia ordosica, Caragana intermedia, Salsola ruthenica and Agriophyllum squarrosum showed that plants response to the wind stress mainly in the following two ways across species: First, reducing the mechanical stress caused by wind through lower height, smaller crown width, biomass and leaves. Second, increasing the resistance abilities against wind by increasing stem base diameter, root length, and changing plant mechanical properties. Species specific adaptive strategies were existed when plants respond wind stress.Above all, the formation of wind erosion patches in sandland vegetation communities will change the environment conditions. Causing negative influences soil seed bank and seedling bank conditions, and the restoration of plants in the patches. Denudation caused by wind erosion will also affected the growth and survival of plants. Species specific adaptive strategies were existed when plants respond wind stress in Mu Us Sandland, and the plant community can resistant strong wind, relatively. In this case, in the process of restoration of sandland vegetation, the environment conditions should be improved specific (increase soil nutrients and create artificial sand barriers) and the soil seed bank should be replenished regularly. In addition, the plant species which have higher adaptive abilities should be chose for the vegetation restoring. |
| 中文关键词 | 毛乌素沙地 ; 沙地植被风蚀斑块 ; 风因子 ; 种苗库 ; 沙地植被适应性 |
| 英文关键词 | Mu Us Sandland Wind Erosion Patches In Sandland Vegetation Communities Wind Factor Soil Seed Bank and Seedling Bank Adaptation Strategy of Sand Vegetation |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院植物研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288217 |
| 推荐引用方式 GB/T 7714 | 张曙东. 毛乌素沙地植被风蚀斑块的环境特征及植物适应性[D]. 中国科学院大学,2018. |
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