策勒绿洲-沙漠过渡带不同植被沙丘表面风沙沉积物粒度特征分析研究

通过对策勒绿洲-沙漠过渡带不同植被类型下沙丘表层风沙沉积物粒度分布特征进行研究,探讨不同荒漠植被类型下风沙沉积物的沉积规律。结果表明:胡杨、骆驼刺、柽柳、花花柴灌丛沙堆表层沉积物粒级组成均以极细砂(57.20%-60.37%)为主,其次为极粗粉砂(18.47%-21.34%)和细砂(16.56%-19.03%),骆驼刺灌丛沙堆表面整体风沙沉积物平均粒径最细(84.06μm),胡杨沙堆表面整体沙物质平均粒径最粗(88.88μm)。四种植被沙堆表面沙物质的分选性总体上在中等-较好水平,分选系数介于1.44-2.02之间,胡杨沙堆表层沙物质的偏度值在顶部附近属于极负偏,骆驼刺、柽柳、花花柴灌丛沙堆表面沙物质均为负偏。峰度值介于0.95-1.51之间,胡杨沙堆顶部附近及骆驼刺沙堆表层沙物质主要属于窄峰态,柽柳、花花柴沙堆表面沙物质属于中等峰态。沙物质平均粒径与偏度值呈极显著正相关性(p<0.01),沙物质的分选系数与峰度值呈极显著正相关性,沉积物粒度特征空间差异主要受物源、植被高度、冠型、疏透度等因素影响。

Analysis of grain size characteristics of aeolian sediments on the surface of different vegetation dunes in the Cele oasis-desert ecotone

By analyzing the grain size distribution characteristics of aeolian sandy sediments on the dune surface under different vegetation types in the Cele oasis-desert ecotone,the sedimentary regularity of wind-sand sediments under the action of different desert vegetation and the difference of vegetation′s sand-fixed capacity were discussed.The results showed that the grain size components of the surface sediments of Populus euphratica,Alhagi sparsifolia,Tamarix and Karelinia caspia shrubs are mainly composed of very-fine sand(57.20%-60.37%),followed by very coarse silty sand(18.47%-21.34%)and fine sand(16.56%-19.03%).The average particle size of the overall aeolian sediment on the surface of Alhagi sparsifolia shrub sand pile is the smallest(84.06μm),and that of Populus euphratica is the coarsest(88.88μm).The sorting properties of sand material on the surface of four kinds of vegetation sand piles are generally moderately well sorted(1.44-2.02).The skewness of the surface sand material of the Populus euphratica sand pile is very fine skewed near the top.The surface sand material of the Alhagi sparsifolia,Tamarix and Karelinia caspia shrubs are all fine skewed.The kurtosis value is between 0.95 and 1.51,the surface sand material near the top of Populus euphratica and Alhagi sparsifolia sand piles mainly belong to leptokurtic distribution.While the surface sand materials of Tamarix and Karelinia caspia shrubs are of mesokurtic distribution.The average grain size of sediment is significantly positive correlated with the skewness value(p<0.01),and the sorting coefficient of sediment is significantly positive correlated with the kurtosis value.The spatial differences of sediment particle size are mainly affected by provenance,vegetation height,canopy type and porosity.