南昌厚田沙地蔓荆(Vitex trifolia)灌丛沙堆的沉积物与空间格局特征

Sediments and spatial pattern characteristics of Vitex trifolia nebkhas in the Houtian sandy land of Nanchang,China

为探讨亚热带湿润地区不同演化阶段灌丛沙堆的特征及其与环境间的相互作用关系,以南昌市厚田沙地蔓荆(Vitex trifolia)灌丛沙堆为研究对象开展野外调查与研究,对各演化阶段灌丛沙堆的形态参数进行实地测量以分析其形态特征,对不同地貌部位的表层沉积物进行采样以分析其粒度特征,并通过野外实地定位与遥感卫星影像图记录沙堆位置,以分析灌丛沙堆的空间分布格局。结果表明:厚田沙地蔓荆灌丛沙堆以稳定阶段为主,占比58.82%,衰退阶段次之,占比36.90%,发育阶段最少,仅占4.28%;各基本形态参数表现为稳定阶段>衰退阶段>发育阶段。沙堆表层的沉积物表现为稳定阶段细颗粒较多,发育阶段粗颗粒较多,衰退阶段居中;平均粒径表现为稳定阶段最小,为1.86Ф,衰退阶段次之,为1.75Ф,发育阶段最粗,为1.67Ф;顶部—中部—边缘—丘间低地的各地貌部位中,稳定和衰退阶段沉积物的平均粒径逐渐变粗,发育阶段无明显变化趋势。灌丛沙堆整体在大部分距离尺度上呈聚集分布状态,各演化阶段的沙堆中,发育阶段与其他两阶段的沙堆在各距离尺度上均无关联性,稳定与衰退阶段的沙堆在中小距离尺度上呈正关联性,反映出厚田沙地主要灌丛沙堆间的相互依赖性及群体效应。

In order to explore the characteristics of nebkhas at different evolution stages and their interaction with the environment in subtropical humid regions,field investigations and researchs were carried out with the Vitex trifolia nebkhas in the Houtian sandy land of Nanchang City as the research object.The morphological parameters of the nebkhas in each evolutionary stage were measured in the field to analyze the morphological characteristics,the surface sediments of different geomorphological positions were sampled to analyze the grain size characteristics,and the location was recorded through field positioning and remote sensing satellite images to analyze the spatial distribution pattern of nebkhas.The results showed that the nebkhas in the Houtian sandy land were mainly in the stable stage and accounting for 58.82%,followed by the recession stage and accounting for 36.90%,the developing stage was the least and accounting for only 4.28%,the basic morphological parameters of the nebkhas are stable stage>recession stage>developing stage.The sediments on the surface of the nebkha are characterized by more fine particles in the stable stage,more coarse particles in the developing stage,and intermediate in the recession stage.The average particle size is the finer in the stable stage which is 1.86Ф,followed by the recession stage which is 1.75Ф,and the coarsest in the developing stage which is 1.67Ф;from the topmiddle-edge-interdune of the nebkha,the average particle size of the sediments in the stable and recession stages gradually becomes coarser,and there is no obvious change trend in the developing stage.The nebkhas as a whole presented the aggregated distribution on most distance scales;among the nebkhas in each evolution stage,the nebkhas between the developing stage and other stages have no correlation at each distance scale,the stable and recession stages presented a positive correlation on the small and medium distance scales.Reflecting the interdependence and group effect between the main nebkhas in the Houtian sandy land.