生物土壤结皮对库布齐沙漠北缘土壤粒度特征的影响

Effect of Biological Soil Crusts on Features of Grain Size in the Northern Margin of Hobq Desert

对库布齐沙漠北缘不同发育阶段的生物土壤结皮及其下层土壤粒度特征进行分析。结果表明:流动沙地和藻类结皮表层均以细砂和中砂成分为主,藓类结皮表层以细砂和极细砂为主。生物土壤结皮表层的中粉砂至黏土、粗粉砂和极细砂含量均高于其下层土壤。两种结皮样地均属于分选性较差等级,但结皮下层土壤分选性中等,3类曲线均不对称,属于正偏-极正偏等级,藓类结皮和藻类结皮表层的峰形均属于中等尖锐水平,而流动沙地的曲线尖窄。生物土壤结皮的成土作用随着结皮的发育阶段和土层深度的增加而表现出差异性和复杂性。

Grain size features of biological soil crusts and its subsoil in the northern margin of Hobq Desert at different developmental stages are studied by the method of particle-size analysis in this article.The fine sand and medium sand dominate the drifting sand and algal crust surface,and the fine sand and very fine sand prevail on the surface of moss crusts.The content of clay,medium silt,coarse silt and very fine sand on the crust surface are much more than that of same samples under the crust.The moss and algal crusts are very poor in sorting feature,however,soil under the crust is medium.Moreover,curves of drifting sand,moss crust and algal crust are all asymmetric in positive skewed distribution.The peaky curves of moss crust and algal crust are moderate,but that of drifting sand is very sharp.Therefore,soil formation effect of biological crust displays the difference and complexity at the different developmental stages and depth of the soil.