Sandy grassland blowouts in Hulunbuir,northeast China:geomorphology,distribution,and causes

来源 :自然科学进展(英文版) | 被引量 : 0次 | 上传用户:yqligjs
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
A sandy grassland blowout consists of an aeolian depression formed in top soil and the underlying sand deposit underlie,and the adjoining redeposit of sand derived from the depression. Research based on field survey and topographic mapping combined with aerophotograph interpretation reveals that: (1) All the three sand land tracts in Hulunbuir Grasslands are composed of blowout depressions and adjoining dunes, with interlaying remnants of sandy grasslands as background; (2) blowout depressions and their adjoining dunes can be classified according to their morphometric characteristics, development stages, and initiating factors; (3) blowouts develop mostly in the upper parts of sidelong aweather and sunward slopes inclining southwestward when west wind prevails; (4) initiation of blowouts is closely related with the coupling of extreme droughts and wide spread intense human disturbance to the fragile topsoil layer. The investigations indicate that key factors to prevent desertification are to protect grassland vegetation and topsoil.
其他文献
For the aim of getting macromolecular flocculant,we studied the copolymerization of acrylic acid onto Rhi.oryzae cell wall structural polysaccharide by the init
综合评述了针对不同的原材料木质陶瓷的制备方法.介绍了木质陶瓷的微观结构及其在焙烧过程中的变化机理.概述了木质陶瓷的各种性能.最后总结了木质陶瓷作为功能材料和结构材
研究了Nb离子注入的γ TiAl合金在 1 1 2 3K和 1 1 73K空气中的高温循环氧化行为 ,用配有能谱仪的扫描电子显微镜对氧化层的形貌、显微结构进行了分析 ,用俄歇谱仪分析了注入
利用微波加热柴油机排气微粒过滤体是一种有望解决过滤体热再生易损坏难题的新颖方法。本文针对自行设计的过滤体微波加热再生系统建立了一个 2维非稳态传热传质模型。模型考
目的 构建间隙连接蛋白43(Cx43)和绿色荧光蛋白(GFP)双基因共表达重组腺病毒载体.方法 利用PCR方法从真核表达载体pcDNA3.0-Cx43扩增Cx43片断,利用DNA重组技术,将目的基因Cx4
本文对高温火团诱导的爆炸及惰性颗粒的抑爆过程进行了数值研究.这种带激波的两相化学反应流动,由于各种特征时间的差异,方程具有刚性.本文利用分裂格式处理方程刚性,用全耦
根据纤维素、半纤维素、木质素在高温高压水中分解速度相差很大的特点,提出了一条稻壳资源化的新工艺,以便减少废弃物、最大限度地得到糖类化合物。新工艺主要包括连续水蒸汽蒸
提出了一种新的氧感应膜的制备方法,大大提高了氧感应膜的信号强度和对氧的灵敏度.以钌的邻菲咯啉络合物为感应指示剂,根据荧光猝灭原理研制了一种氧传感器.该传感器采用非接触
采用TGA(热解重量分析法)技术,考察了山西省晋城市区生活垃圾不同组分的着火及燃烧特性。实验给出了原生垃圾中不同组分(包括废塑料类、废纸类、废弃织物类、植物类、厨余类和
Traditional clustering algorithms generally have some problems, such as the sensitivity to initializing parameter, difficulty in finding out the optimization cl