中文摘要：

通过室内压力陶土板系统测定土壤含水率与基质势的关系与Star-1土壤水分物理特征测定系统确定非饱和土壤水力传导度的方法，结合应用van Genuchten公式模拟，分析了位于腾格里沙漠东南缘包兰铁路沙坡头段人工生态防护体系生物土壤结皮的水文物理特征，确定了其水分特征曲线、非饱和土壤水力传导度、非饱和弥散系数，并与原始沙丘沙进行比较。结果表明，生物土壤结皮的持水能力是沙丘沙的3—9倍。当土壤基质势在-1--13000cm的较高范围变化时，生物土壤结皮平均非饱和水力传导度低于沙丘沙（约为12％）；而当土壤基质势在-3000--15000cm的较低范围变化时，沙丘沙的平均非饱和水力传导度又大大低于生物土壤结皮（约为91．0％）。正是由于生物土壤结皮特殊的质地与结构，使其非饱和水力传导度随着土壤基质势的降低，以及土壤含水量的减少，而趋于增大。与原始沙丘沙比较，生物土壤结皮独特的水文物理特点决定了。它对荒漠地区土壤微生境的改善与促进作用，特别是通常情况下的高持水能力与低土壤基质势条件下的较高非饱和水力传导度，能够提高浅层土壤水分的有效性，有利于人工生态防护体系主要组分浅根系灌木、草本植物与小型土壤动物的生存繁衍。

英文摘要：

The biological soil crusts BSC play several important roles in many arid and semi-arid ecosystems around the world. Their effects on soil hydrology, however, are poorly understood. The experiments under 15 Bar Ceramic Plate Extractor, Star- 1 soil hydrophysical characteristics determination system, and with the van Genuchten closed-form equation for predicting the hydraulic conductivity of unsaturated soils are conducted using two samplers of the BSC and the shifting dune sand. The results indicate that the water holding capacity of BSC is 3 to 9 times magnitude than that of shifting dune sand; when the matrix potential varies from - 1 to - 3 000 cm, the unsaturated soil hydraulic conductivity of BSC is about 12 % lower than that of the dune sand, while the matrix potential varies within- 3000-- 15000 cm, the comparable value for BSC is about 91.0% and higher than that of shifting dune sand. The particular structure and particle size distribution contribute to the variation of the unsaturated soil hydraulic conductivity of the two soils, where biological crusts are formed by living organisms and their byproducts, creating a crust of soil particles bound together by organic materials. It improves the micro-habitat of desert soils and increases the availability of soil moisture to shallow rooted shrubs, herbages and micro soil animals in the artificially re-vegetated ecosystems.