防沙治沙和生态修复工程实施之后,有植物定植的沙丘表面广泛发育了生物结皮。揭示不同类型人工植被与生物结皮发育特征之间的关系对受损荒漠系统的生态修复具有重要的参考价值。采用野外调查的方法,对毛乌素沙地南缘沙区不同类型人工植被区（羊柴Hedysarum mongdicum、小叶杨Populus simonii、沙柳Salix psammophila＋羊柴、紫穗槐Amorpha fruticosa和沙地柏Sabina vulgaris）生物结皮厚度、抗剪强度、总盖度及分盖度进行了测定。结果表明：不同类型人工植被区生物结皮发育特征表现出较大差异,小叶杨样地生物结皮厚度、抗剪强度和总盖度均显著高于其他类型人工植被区（P〈0.05）,羊柴、沙柳＋羊柴样地生物结皮的盖度较低。分盖度的调查结果表明,小叶杨样地生物结皮以藓类结皮为主,其余样地则以藻类结皮为主。生物结皮盖度随植被盖度的增加而减少,随表层（0~5cm）土壤含水量的增加而增加。小叶杨的建植有利于生物结皮的扩殖,沙柳行带间栽植羊柴则不利于生物结皮的发育。
Widespread biological crusts have been developed at the dune surface after implementation of de- sertification control and ecological rehabilitation projects in the sandy area in Northern China. Clarifying the relationships between characteristics of biological crusts development and different types of artificial vegeta- tion has significant influence on the ecological rehabilitation of damaged ecosystem. Thicknesses, shear strength, coverage of biological crusts were examined under different types of artificial vegetation （Hedysa- rum mongdicum, Populus simonii, Salix psammophila, Amorpha fruticosa and Sabina vulgaris ） in southern Mu Us sandy land by field investigation methods. The results showed that characteristics of biologi- cal crusts development under different vegetation types varied greatly. Thicknesses, shear strength, cover- age of biological crusts under Po simonii site significantly higher than other sites （P~0.05）. Coverage of biological crusts under H. mongdicum and S, psammophila site was lower relatively. P. simonii site were dominated by mosses crusts while the other sites were dominated by algae crusts. Correlation analysis indicated that coverage of biological crust decreased with increasing of vegetation cover, increasing with surface （0--5 cm） water contents of soil. These results suggest that plantation of P. simonii is recommen- ded for establishment of biological crust, and plantation of S. psammophila with H. mongdicum is not conductive to development of biological crusts.
Journal of Desert Research
Mu Us sandy land