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首页> 外文期刊>Chinese science bulletin >The microstructure and formation of biological soil crusts in their early developmental stage
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The microstructure and formation of biological soil crusts in their early developmental stage

机译：生物土壤结壳发育初期的微观结构和形成

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The biological soil crust serves as one of the biological factors contributing to the sand fixation in the Gurbantunggnt Desert, the largest fixed and semi-fixed desert in China. This study was conducted to investigate the microstrueture and formation of biological soil crusts which develop as a result of occurrence of cryptogams. One year removal of biological soil crusts, the exposed surface could be fixed by bacteria, which make sand particles cohere by exopolysaccharides. The exopolysaccfaarides 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 cyanobacteria. 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
机译：在中国最大的固定和半固定沙漠古尔邦通特沙漠中，生物土壤结皮是导致固沙的生物因素之一。进行这项研究以研究由于隐孢子虫的发生而形成的生物土壤结壳的微观结构和形成。去除生物土壤结皮一年后，暴露的表面可能会被细菌固定，从而使沙粒与胞外多糖结合。胞外多糖主要由葡萄糖，甘露醇，阿拉伯糖和半乳糖组成。这种地壳的压力强度为13.42±-1.38 Pa。在裸露的沙质表面恢复四年后，由丝状蓝细菌群落在土壤表面定殖而形成的生物土壤地壳主要由小隐色子控制。发生为被胶状鞘包围的细丝簇。在这个发展阶段，固沙的主要贡献者已从细菌变为丝状蓝细菌。对这种硬皮的显微镜检查表明，丝状蓝细菌和细胞外聚合物分泌物形成了复杂的网络，该网络将矿物质颗粒和更细的颗粒结合并截留在细丝表面。这些作用增强了土壤的内聚力和抗侵蚀性。这种地壳的压力强度为32.53 + -3.08

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