沙漠公路防护林影响下近地表风沙流粒度特征的空间分异

Spatial Variation of Grain-size Characteristics of Near Surface Aeolian Sand Transport Under Desert Highway Shelterbelt

利用BSNE集沙仪对沙漠公路两侧灌木混交防护林影响下的近地表风沙流粒度特征进行了研究,结果表明:在水平方向上,风沙流粒度沿主风向从林带上风侧到下风侧邻近林带流沙地,平均粒径减小,分选变差,而且越向下风向变化越大,但两条阻沙林带间风沙流粒度受沙丘影响不同于其他点,其平均粒径增大,分选性变好;在垂直方向上,风沙流平均粒径随高度先减小后增大,在植物冠层高度之上略有增大。受防护林影响,风沙流粒度的垂直分异减缓,而不同观测点之间的季节变化增大。防护林影响范围内近地表风沙流粒度的时空变化特征与防护林垂直疏透度、季节以及防护林内具体位置的微环境有关。

BSNE sampler was used to monitor the grain-size characteristics of near surface aeolian sand transport under desert highway shelterbelt. The results showed that in the horizontal direction, along the main wind direction from windward to leeward moving sand nearby the shelterbelt, the mean grain-size of aeolian sand transport decreased and the sorting coefficient became poor, and that the more downward the wind, the greater the changes. But between the two belts of sand-resisting forest, the grain-size characteristics of aeolian sand transport affected by the sand dunes were different with other points, its mean grain-size increased and the sorting coefficient became large. In the vertical direction, the main grain-size of aeolian sand transport firstly decreased and then increased, and the grain-size slightly increased above the plant canopy. Affected by the shelterbelt, the grain-size of near surface aeolian sand transport decreased in the vertical variation, but the grain-size of aeolian sand transport increased between different points in different seasons. Within the influence of shelterbelt, the spatial variation of grain-size characteristics of near surface Aeolian sand transport were relevant with the vertical porosity of the shelterbelt, season and the micro environment at specific location in the shelterbelt.