The microstructure and formation of biological soil crusts in their early developmental stage

编号 zgly0000371482

文献类型 期刊论文

文献题名 The microstructure and formation of biological soil crusts in their early developmental stage

学科分类 220.1040;森林土壤学

作者 ZHANGYuanming 

作者单位 XinjiangInstituteofEcologyandGeography 

母体文献 Chinese Science Bulletin;中国科学通报: 英文版 

年卷期 2005,50(2)

页码 117-121

年份 2005 

分类号 S153  S157 

关键词 生物土壤结皮  显微结构  土壤黏结力  沙漠  形成条件  化学因素  物理因素 

文摘内容 The biological soil crust serves as one of the biological factors contributing to the sand fixation in the Gurbantunggut Desert, the largest fixed and semi-fixed desert in China. This study was conducted to investigate the microstructure and formation of biological soil crusts which develop as a result of occurrence of cryptogams. One year after removal of biological soil crusts, the exposed surface could be fixed by bacteria, which make sand particles cohere by exopolysaccharides. The exopolysaccharides were mainly composed of glucose, mannitol, arabinose and galactose. The intension of pressure for this kind of crust is 13.42+1.38 Pa. After four-year recovery of the exposed sandy surface, the biological soil crust resulting from the colonization of soil surface by communities of filamentous cyanobacteria were mainly dominated by Microcoleus, which occurred as a cluster of filaments surrounded by a gelatinous sheath. At this developmental stage, the main contributors for sand fixation were changed from bacteria to filamentous cyauobacteria. Microscopic examination of this kind of crust revealed an intricate network of filamentous cyanobacteria and extracellular polymer secretions, which binds and entraps mineral particles and finer particles on the filament surface. These effects enhance soil cohesion and resistance to erosion. The intension of pressure for this kind of crust is 32.53±3.08 Pa。