乌兰布和沙区不同下垫面的土壤风蚀特征

发布时间：2018-01-25 01:03

本文关键词： 风沙流结构输沙率土壤风蚀粒度分析乌兰布和沙漠　出处：《林业科学》2017年03期 　论文类型：期刊论文

【摘要】：【目的】研究荒漠生态系统典型植被群落对近地层风沙活动的影响,揭示荒漠生态系统中不同下垫面条件的土壤风蚀特征。【方法】在乌兰布和沙区东北缘荒漠-绿洲过渡带内,选取油蒿半固定沙丘(盖度约20%)、白刺半固定沙丘(盖度约30%)、油蒿固定沙丘(盖度约40%)、白刺固定沙丘(盖度约40%)、流动沙丘(CK)5种典型下垫面,运用风蚀钎和风沙流采集系统,实时监测5种下垫面的风蚀动态,定量分析不同下垫面条件下的土壤风蚀量、风蚀物的垂向分布及粒度组成的差异性。【结果】乌兰布和沙区不同下垫面同期土壤风蚀深度为:流动沙丘油蒿半固定沙丘白刺半固定沙丘油蒿固定沙丘白刺固定沙丘,当风速达到4.1 m·s~(-1)时,流动沙丘即可观察到沙粒蠕动,当风速达5.1 m·s~(-1)时积沙仪可收集到风蚀物。油蒿半固定沙丘、白刺半固定沙丘、油蒿固定沙丘、白刺固定沙丘的风速分别达到6.3,6.5,6.8,7.9 m·s~(-1)时方可发生风蚀;5种下垫面0~100 cm垂直断面上,67.6%~90.0%的风蚀输沙均分布于30 cm高度范围之内,挟沙气流中输沙率随高度增加呈幂函数规律递减,随风速增大呈幂函数规律递增,各高度层风蚀物粒度组成呈单峰态分布,峰值处在250~100μm之间,0~20 cm高度层峰值与其余各层的峰值范围差异明显且偏向粒径趋大的方向;自下而上,极细沙的粒度构成比例呈递增趋势,中沙的粒度构成比例呈递减趋势。【结论】随着植被盖度的增加,土壤风蚀程度显著减轻,流动沙丘、半固定沙丘、固定沙丘年风蚀深度依次降低。盖度为40%的油蒿、白刺群落,其地表风蚀深度仅为流动沙丘同期风蚀深度的1.73%~1.52%,0~100 cm高度范围内的输沙率仅为流动沙丘输沙率的6.6%~5.1%。在荒漠生态系统中,植物群落主要通过覆盖地表、提高下垫面的粗糙度和拦截沙粒的运动来缓解气流对地表的侵蚀作用。因此,在防沙治沙工程实施过程中,要充分考虑和利用植被防风抗蚀的生态效应。
[Abstract]:[objective] to study the effects of typical vegetation communities on the aeolian activities in desert ecosystems. To reveal the characteristics of soil wind erosion in different underlying surface conditions in desert ecosystem. [methods] in the desert oasis transitional zone of the northeast margin of Wu Lan Buhe region, the semi-fixed sand dunes of Artemisia annua were selected (coverage was about 20%). Spurs semi fixed sand dunes (coverage about 30%), Artemisia annua fixed sand dunes (about 40%), Spurs fixed sand dunes (about 40% cover, flowing sand dunes) 5 typical underlying surfaces. By using wind erosion drill and wind sand flow acquisition system, the wind erosion dynamics of five kinds of underlying surfaces were monitored in real time, and the amount of soil wind erosion under different underlying surfaces was quantitatively analyzed. The vertical distribution and particle size composition of wind erosion materials are different. [results] the depth of wind erosion in different underlying surfaces of Wu Lan Buhe sand area is:. The flow sand dune oil artemisia semi-fixed sand dune spur semi-fixed sand dune fixed sand dune fixed sand dune. When the wind speed is up to 4.1 m 路s-1), the movement of sand particles can be observed in the mobile sand dunes, and when the wind speed reaches 5.1 m 路s-1), the sand accumulator can collect the wind erosion. The semi-fixed sand dunes of Artemisia oil can be collected. The wind erosion occurred only when the wind speed of the semi-fixed sand dunes, the Artemisia annua fixed sand dunes and the Spurs fixed sand dunes reached 6.3m6.5m 路s-1 and 6.87.9m 路s-1, respectively. 90.0% of the sediment transported by wind erosion was distributed in the height range of 30 cm on the 0 ~ 100 cm vertical section of 5 kinds of underlying surfaces. The sediment transport rate decreases with the increase of height and increases with the increase of wind speed. The particle size composition of each layer of wind erosion shows a single peak distribution, and the peak value is between 250 渭 m and 100 渭 m. The peak value of 0 ~ 20 cm height layer is obviously different from that of the other layers and is inclined to the direction of larger particle size. From bottom to top, the grain size composition ratio of very fine sand is increasing, while that of middle sand is decreasing. [conclusion] with the increase of vegetation coverage, the degree of soil wind erosion is significantly reduced, and the flow sand dunes. The annual wind erosion depth of semi-fixed sand dune and fixed sand dune decreased in turn. The surface wind erosion depth of Artemisia annua and Spurr community with coverage of 40% was only 1.73% of that of flowing sand dune in the same period. The sediment transport rate in the range of 100 cm is only 6.6% of the sand transport rate in the moving dunes. In the desert ecosystem, plant communities mainly cover the ground surface. The roughness of the underlying surface and the movement of intercepting sand particles are improved to alleviate the erosion effect of air flow on the surface. Therefore, the ecological effect of vegetation wind and erosion resistance should be fully considered and utilized in the process of sand prevention and control project.
【作者单位】：中国林业科学研究院沙漠林业实验中心内蒙古磴口荒漠生态系统定位观测研究站;
【基金】：“十二五”科技支撑计划项目(2012BAD16B0103) 中央级科研院所基本科研业务专项(CAFYBB2016MB003)
【分类号】：S157.1
【正文快照】： 土壤风蚀(soil wind erosion)是指土壤及其母质在风力作用下剥蚀、分选、搬运的过程,其实质是气流或气固两相流对地表物质的吹蚀和磨蚀塑造地表景观的一个基本地貌过程(吴正,2003)。土壤风蚀不仅是干旱、半干旱地区主要的土地退化过程,而且是导致干旱、半干旱地区土地沙漠化与

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