毛乌素沙地南缘半固定沙丘风沙输移物特征

通过连续动态观测,获取毛乌素沙地南缘典型半固定沙丘表面风沙输移物,测量了风沙活动中不同沙丘部位的风蚀深度,并对风沙输移物及其养分进行了初步分析。结果表明:风沙活动期间沙丘顶部的风蚀深度最大,沙丘迎风坡次之,而丘间地的风蚀深度最小;沙丘顶部和迎风坡的输移物以中沙和细沙为主,养分含量较低,丘间地颗粒较细且养分含量较高;土壤养分含量与颗粒大小存在显著的负相关关系。迎风坡和丘顶处在风蚀亚环境而难以被植被固定,进而加速了风蚀过程;丘间地风沙活动较弱,风积物中养分含量较高的细颗粒物质促进了植被的发育,因而减弱了局地风速。

Features of Drifting Sand of Semi-fixed Dunes in the South Edge of Mu Us Sandy Land of China

By continuous dynamic observation, we collected the drifting sand on the surface of typical semi-fixed dunes in the south edge of Mu Us Sandy Land. Besides, we analyzed the erosion depths in different dune positions as well as nutrient contents of sand transport materials. The results indicate that the erosion depths on the top of the dune are the largest during wind activity, with upwind slope the less and interdune the least. The sand transport materials on the top of the dune and the upwind slope are mostly composed with medium particles and fine particles, which are low in nutrient contents. However, the interdune has more fine particles and high nutrient contents. Soil nutrient contents have a negative relationship with sand particle size. The upwind slope and the top of the dune are in the environment of wind erosion, thus they cannot easily be fixed by vegetation and wind erosion process is accelerated. In contrast, the wind activity in the interdune is relatively weak, and the fine particles with high nutrient contents promote vegetation growth and development, which lead to weaker wind velocity.