毛乌素沙地南缘沙区水分入渗特征及其影响因素

Soil Infiltration and Its Affecting Factors in Sandy Area in the South Mu Us Sandy Land

水分入渗是土壤水分循环的重要环节。为探明毛乌素沙地生物结皮覆盖沙区水分入渗特征及其影响因素,采用双环法测定不同类型地表（裸沙、浅灰色藻类结皮、黑褐色藻类结皮和藓类结皮,依次用BS、LC、DC和MC表示）水分入渗速率及其土壤理化性质。结果表明：1与BS相比,LC、DC和MC样地初始入渗率分别减少了37.7%、59.2%和73.6%,稳定前平均入渗率分别减少了37.5%、62.2%和81.3%,稳定入渗率分别减少了13.6%、67.4%和78.9%,累计入渗量分别减少了25.8%、61.3%和78.6%。2不同类型地表达到稳定入渗所需的时间在3~8 min;相关性分析结果显示,水分入渗速率与砂粒和土壤容重呈正相关关系,与粉粒、黏粒、结皮厚度、结皮抗剪强度、结皮层容重和有机碳含量呈负相关关系。3主成分分析结果表明,黏粒、结皮抗剪强度和土壤容重是影响该地区水分入渗速率的主要因子。因此,生物结皮在沙丘表面的形成和发育过程中,通过改变土壤的理化性质,减缓了该地区水分入渗速率,增加了降水的径流流失风险。

Water infiltration is an important part of the soil water cycle. In order to determine the infiltration in sandy soil covered with biological crusts and its affecting factors in the south Mu Us Sandy Land,in this study the moisture infiltration rate and soil physicochemical properties in four land cover types（ bare sand land,light algae crusts,dark algae crusts and mosses crusts） were measured by using double ring methods. Results are as follows：1 Average initial infiltration rates at LC,DC and MC sites were reduced by 37. 7%,59. 2% and 73. 6% respectively compared with the infiltration rate at BS site. Average infiltration rates at LC,DC and MC sites before stabilizing were reduced by 37. 5%,62. 2% and 81. 3% respectively compared with the infiltration rate at BS site. The average stable infiltration rates at LC,DC and MC sites were reduced by 13. 6%,67. 4% and 78. 9% respectively compared with the average stable infiltration rate at BS site. Accumulative infiltration rates at LC,DC and MC sites were reduced by 25. 8%,61. 3% and 78. 6% respectively compared with the accumulative infiltration rate at BS site; 2 The infiltration rate of different land surfaces became stable after 3-8 minutes. Correlation analysis showed that there were the positive correlations between sand and soil bulk density and all the four infiltration indexes,but the negative ones between the infiltration indexes and the silt and clay contents,crust thickness,shear strength of biological crusts and organic carbon content; 3 The principle component analysis indicated that the clay content,shear strength of biological crusts and bulk density of subsurface soil were the major factors greatly affecting the soil infiltration in the study area. Therefore,in the process of formation and development of biological crust on the surface of sand dunes,the change of soil physicochemical properties decreased the infiltration rates and increased the risk of runoff loss.