Knowledge Resource Center for Ecological Environment in Arid Area
| 毛乌素沙地南缘风沙输移物特征及其环境意义 | |
| 其他题名 | Characteristics of Sand Transport Material in the Southern Edge of the Mu Us Sandy Land and Its Envi |
| 王广涛 | |
| 出版年 | 2015 |
| 学位类型 | 硕士 |
| 导师 | 段争虎 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 干旱半干旱地区的自然环境状况近些年来日益受到广大民众的关注，从生态环境的角度来看，这些区域多位于生态环境脆弱的敏感地带，气温、降水、植被状况的扰动都会对当地环境造成剧烈的改变，由此引起的沙漠化问题更为突出。近半个世纪以来，我国沙漠化过程经历了扩张与逆转的变化过程，许多学者从生物量波动与植被覆盖度的变化方面研究了沙漠化正逆过程的驱动机制，而风沙活动主导下的沙漠化物理过程研究相对较少。本文以毛乌素沙地南缘靖边县的沙丘与盐池县的干草原为研究地点，通过野外沙丘风沙活动观测、野外原状土取样结合风洞试验模拟，研究了风沙活动过程中的风蚀状况，并结合运移沉积物的粒度与养分特点探讨了土壤可蚀性以及风沙活动造成的养分损失。 结论如下： （1）在干草原地区，当土壤含水量在1%以下时，不论土壤是否遭受破坏，水分含量对于风沙输移率的影响都很小。 （2）沙丘风蚀物质所有样品的粒度组成都以细沙为主，其次是中沙，粗沙和粉沙含量均在1%以下；干草原土壤风蚀物质细沙含量最高，其次是中沙和粉沙，粗沙与极粗沙含量非常少。 （3）风蚀过程主要作用于表土可蚀性物质，对于极细颗粒和极粗颗粒，风力的侵蚀作用有限。虽然诸如植被覆盖和水分条件在风沙活动中扮演重要角色，但是土壤中粉沙和粘土的含量对于减弱风蚀输移率也起着重要的作用，这种作用在我国干旱半干旱沙漠化高风险地区不容忽视。 （4）土壤风蚀养分在沙丘不同部位的含量差异明显，丘间地有机质、速效磷、速效钾、全磷等养分的含量均显著高于迎风坡和沙丘顶部。这与丘间地水分条件较好和植被覆盖度较高有密切的联系；干草原土壤有机质的平均含量为有8.80g/Kg，总氮平均养分含量0.60 g/Kg，全磷平均含量为0.82 g/Kg，速效磷平均含量为15.95 mg/Kg，速效钾平均含量为209.50 mg/Kg，不同样点的养分状况都存在显著的变化。 （5）风沙活动过程中沙丘顶部的风蚀深度最大，其次是迎风坡，丘间地风蚀作用是微弱，风蚀深度约在10mm以下，甚至会出现微小的风积现象，这主要是丘间地低风速和较高植被覆盖度增大地表粗糙度所致。干草原地区土壤表面遭受轻微适度的人为干扰（例如放牧或者耕作）后，由于粉沙和粘土的存在风蚀输移率仍然非常低，土壤的风蚀量并不会有明显的变化。只有在对地表进行强烈的破坏之后，风蚀量随风速增大才会骤然增加，人类活动才会对这些地区的沙漠化发展起到重要的影响。 （6）风沙活动过程通过输出小于50 mm的细颗粒物质引起了土壤养分的损失，这种形式的养分损失在我国干旱半干旱地区非常重要。实验结果表明在风沙活动期间，样地中大约占总颗粒组分12.5%的细颗粒物质随风蚀作用输出，而这些细颗粒物质中含有相当多的养分。沙漠化过程中除了肥岛效应扮演重要角色外，风沙活动过程中风力作用对细颗粒物质的输移同样对我国干旱半干旱地区的沙漠化问题有重要影响。 |
| 英文摘要 | In recent years, the natural environment in arid and semi-arid regions has arouse wide attentions from general public. From the aspect of the ecological environment, these areas are located in the fragile ecological environment areas, which are sensitive to climate change. The disturbance of temperature, precipitation and vegetation condition will cause severe changes in the local environment, and the resulting desertification problem is more outstanding. Nearly half a century, the process of desertification in China has experienced the the change of expansion and reverse process. Many scholars studied the drive mechanisms on the process of desertification and reverse from the aspect of biomass fluctuate and the change of vegetation coverage . However, the physical process of desertification dominated by wind activities are poorly understood. This study choose the sand dunes existing in Jingbian county and the steppe existing in Yanchi county as research sites, both located in the southern edge of Mu Us sandy land. By observing sand dunes’ activity, sampling undisturbed soil in field as well as conducting wind tunnel test simulation, we studied the wind erosion situation during wind activities. Besides, by combining with the characteristics of transporting sediment grain size and soil nutrients, we discussed soil erodibility and nutrients loss caused by wind activities. Conclusions are as follows: (1) In steppe region, if the soil water contents are under 1%, the effects of moisture contents on sand transport rate are quite weak no matter whether the topsoil is damaged or not. (2) The grain size of sand dunes transport materials are mostly composed of fine particle, the second is medium sand, and the contents of coarse sand and silt are below 1%; among the grain size of steppe soil erode by wind, fine particle content is the highest, followed by the medium sand and silt, the contents of coarse sand and very coarse sand are very low. (3) Wind erosion process mainly acts on topsoil erodibility substance. For the particle size either too tiny or too large, the effects of wind reosion are limited. Although factors such as vegetation cover and water conditions play an important role in wind activities, the contents of silt and clay in the soil are also important in reducing the wind transport rate. This effect in high-risk desertification areas in arid and semi-arid China should not be ignored. (4) The contents of soil erosion nutrients in different parts of the dunes change greatly. Because of high moisture conditions and high vegetation coverage, the levels of organic matter, available phosphorus, available potassiums and total phosphorus in interdunes are significantly higher than the windward slope and dunes at the top. The content of soil organic matter in steppe reaches an average of 8.80 g/Kg, while the average content of total nitrogen is 0.60 g/Kg, total phosphorus content is 0.82 g/Kg , available phosphorus was 15.95 mg/Kg, available potassium content is 209.50 mg/Kg. The results show that nutrient conditions in different locations change significantly. (5) During wind activities, the erosion depth at the top of the dune is the highest , the second is the windward slope and the interdune is the shortest. The erosion depth in the interdune is under 10 mm, and even appears tiny deposition phenomenon, which is the result of low wind speed and high surface roughness caused by high vegetation coverage. After soil surface in steppe region suffered moderate human interference ( for example grazing or farming), the soil erosion amount does not have obvious change as a result of the existence of silt and clay, and the wind transport rate is still very low. Only after import huge damage to the soil surface , the wind erosion amount will increase abruptly with wind speed, and human activities will have an important influence on desertification development in these areas . (6) Through output fine grain size less than 50mm, wind activities cause soil nutrients loss. This form of nutrients loss is very important in arid and semi-arid areas in China. The experimental results show that during wind activities, fine particulate matter which occupies about 12.5% of the total grain composition is output by wind erosion in the sample area, and these fine particulate matter contains quite a lot of nutrients. This confirms that in addition to fertile island effect plays an important role in the process of desertification, fine particulate matter transported in the wind activities also has great influence on desertification problems in arid and semi-arid areas in China . |
| 中文关键词 | 风沙活动 ; 粒度 ; 养分 ; 毛乌素沙地 |
| 英文关键词 | wind activities grain size nutrients Mu Us sandy land |
| 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/2XILL650/287513 |
| 推荐引用方式 GB/T 7714 | 王广涛. 毛乌素沙地南缘风沙输移物特征及其环境意义[D]. 中国科学院大学,2015. |
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