中文摘要：

以低覆盖度（约20%）油蒿群丛为研究对象,采用多点式自记风速仪,研究行带式配置和随机分布的防风效果。结果表明：1）行带式配置的油蒿群丛的防风效果大于同覆盖度的随机分布的油蒿群丛,行带式配置具有显著的防风效果;2）在灌丛与灌丛之间形成的类似“狭管”流场的局部,有局部提升风速的作用,导致群丛内局部风速大于对照风速,致使随机分布的油蒿群丛内流场结构复杂、变化多样,低覆盖度时,沙地处于半固定、半流动状态,稀疏群丛内同时存在风蚀和积沙现象;3）除去两个极值后,行带式配置的油蒿群丛内平均地表粗糙度是随机配置的4倍,平均摩阻速度是随机配置的1.3倍,说明行带式配置具有显著的防止风蚀、固定流沙的作用。

英文摘要：

In this study we investigated the windbreak effects of a shrub（ Artemisia ordosica ） with its 20 % cover established for the purpose of sand-fixation. Wind velocity was measured at different locations and heights along the shrub belt and of the random distribution shrubs by using multiple-sensor automatic anemoscope （GB-228） during windy season （from February to April）. Statistical analysis indicated that when the cover was about 20 %, the belt scheme of A. ordosica was more effective for wind breaking than its randomly distribution. Random distribution of the shrubs formed many ＂narrow pipes＂ out of gaps between shrubs, which increased wind velocity, and resulted in greater wind velocity than that measured in the open. The flow field structure of the randomly distributed A. ordosica shrub was complicated and changeable, and the sand-dunes was in status of the semi-mobile or sem-fixed, which allowed wind erosion and sand accumulation in the thin stands to occur. After eliminating maximum and minimum, soil surface roughness and friction speed were found to be about 4 and 1.3 times greater in the belt than in the randomly distributed shrubs, respectively, indicating that the belt scheme enhanced the function of preventing wind erosion and fixing drift sand.