地理科学 ›› 2013, Vol. 33 ›› Issue (9): 1117-1124.doi: 10.13249/j.cnki.sgs.2013.09.1117

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包兰铁路沙坡头段防护体系生物土壤结皮沉积特征及其风沙环境意义

张加琼(), 张春来(), 王焕芝   

  1. 北京师范大学地表过程与资源生态国家重点实验室 北京师范大学防沙治沙教育部工程研究中心, 北京 100875
  • 收稿日期:2013-01-07 修回日期:2013-02-19 出版日期:2013-09-30 发布日期:2013-06-13
  • 作者简介:

    作者简介:张加琼(1984-),女,藏族,四川小金人,博士研究生,主要研究方向为土壤风蚀。E-mail:jqzhang@mail.bnu.edu.cn

  • 基金资助:
    国家自然科学基金(41171004)资助

Distribution of Biological Soil Crust and Its Significance to Aeolian Environment in Shapotou Section Protective System of Baotou-Lanzhou Railway

Jia-qiong ZHANG(), Chun-lai ZHANG(), Huan-zhi WANG   

  1. State Key Laboratory of Earth Surface Processes and Resource Ecology, MOE Engineering Center of Desertification and Blown-sand Control at Beijing Normal University, Beijing 100875, China
  • Received:2013-01-07 Revised:2013-02-19 Online:2013-09-30 Published:2013-06-13

摘要:

分析了沙坡头段防护体系生物土壤结皮类型、地表紧实度和沉积物机械组成的空间分布及其对风沙环境的指示意义。结果显示,沿主风向生物土壤结皮从无发育、斑块状分布,到连续分布;类型由地衣-藻结皮为主逐渐演变为苔藓结皮与其交错分布,地表紧实度逐渐增大。表层沉积物粒径随防护距离增大逐渐变细,悬移组分含量增加,结皮层粘粒和粉砂含量较高。表明防护体系内风沙活动由强烈蚀积逐渐转变为沉积主导,风沙环境趋于稳定。结皮沉积特征随沙丘地形起伏表现出波动变化,显示沙丘地形对局地风沙环境的影响。

关键词: 生物土壤结皮, 机械组成, 紧实度, 风沙环境

Abstract:

This study analyzed the spatial distribution of the type and thickness of biological soil crust, ground surface compaction and grain-size composition of surface sediments through a cross-section parallel to the prevailing wind direction in Shapotou section of Baotou-Lanzhou railway protective system, and discussed the significance of the biological soil crust to the changes of the aeolian environment in the protective system. Results showed that the biological soil crust was developed gradually from lichen-algae crust to crossly exist of moss crust and lichen-algae crust along the prevailing wind direction in the protective system. The crust distribution was developed from no crust, patch style to continuous crust formation with gradually increasing on surface compaction along the prevailing wind direction in the vegetation area of the protective system. The ground surface compaction was much higher in the vegetation area than the mobile dune area no matter with developed crust or not. The grain size of the surface sediments became fine, and the sorting got worse with the increasing of the protective distance. Suspended components (grain size<0.1 mm) increased along the protective distance. The suspended component was much higher in the vegetation area than in the mobile dune area along the cross-section direction, and much higher in the crust layer than the 5 cm layer under curst in the depth direction. The content of silt and clay in the biological soil crust layer was much higher than its below layers in the vertical direction, and they increased with undulation which caused by the terrain change of the fixed dunes along the cross-section. These results implied that the aeolian environments tended to be stable along the cross-section. It changed gradually from intense erosion and deposition aeolian activity in the upwind mobile dune area to deposition dominated aeolian environment in the downwind vegetation area of the protective system. The upwind area of the vegetation area that without crust developed was a transition area from erosion and deposition to deposition dominated aeolian environments. There was still erosion and deposition activity at this area but the intensity was much less than the mobile sand area. Relative stable aeolian environment produced advantageous conditions for the development of the biological soil crust, which inversely enhanced surface stability and its wind erosion resistance ability remarkably in the vegetation area of the protective system. The better-developed moss crust was distributed in the gentle terrain area of the fixed and semi-fixed dunes while the lichen-algae crust was widely distributed in the vegetation area of the protective system. This spatial distribution variation of difference type crust implied the spatial difference on surface stability of the aeolian environments in the protective system. Spatial distribution of the attributes of the biological soil crust vibrated with the terrain of fixed dunes showed that dune terrain influenced local aeolian environment in the protective system.

Key words: biological soil crust, gain-size composition, surface compaction, aeolian environment

中图分类号: 

  • K903