新疆和田河流域柽柳沙堆的生物地貌发育过程

柽柳沙堆是我国干旱区分布最为广泛的灌丛沙堆类型之一。在实地考察新疆和田河流 域柽柳生态地理特征、测量223 个柽柳沙堆形态, 并在两个野外观测点上实测4 个沙堆的风沙流剖面, 结合室内风洞实验段风速8 m/s 条件下模拟沙堆风流场结构等综合分析方法, 本文探讨了柽柳沙堆的生物地貌学特征及其发育过程。结果表明: 研究区柽柳的生态类型属于以胡杨林与灌木林下土壤为基础的吐加依土生境类型, 这个生境类型可以进一步划分为三个亚生境, 这些亚生境反映了柽柳沙堆不同发育阶段的生态环境特征。由于柽柳灌丛的寿命长、木质化枝干的刚性较强、根株萌发力强耐风蚀沙埋, 可对地面风沙流运行产生强烈扰动, 其风速剖面有别于芦苇沙堆和骆驼刺沙堆, 风流场结构有利于聚集风沙, 因此风沙依托柽柳灌丛堆积发育而成的柽柳沙堆平均坡度较大、沙堆存活与发育的周期也较长

Bio-geomorphologic Growth Process of Tamarix nabkha in the Hotan River Basin of Xinjiang

The characteristics of Tamarix shrub's plant ecology,community and environment and its regularities of distribution in space have been investigated in the Hotan River basin of Xinjiang. The shape data of 223 Tamarix nabkhas have been measured,and the structural characteristics of 4 Tamarix nabkha's sand driving wind have been observed at two field observational points. Based on the shape data surveyed and the sand flow materials observed,models of nabkhas have been made according to the proportion. In the wind tunnel,the flow patterns of different shapes of nabkhas have been imitated separately. The results indicated that Tamarix ecological type in the study area belongs to tugaic soil habitat which is based on soil of Populus and shrub forest. This habitat type can be further divided into three sub-habitats of juvenile,mature and post-mature Populus forests,in which Tamarix eco-geographical community is sequential succession. The change of ecological characteristics of Tamarix community in different sub-habitats induces variation of disturbance to sand flow and sand aggregation capability by Tamarix shrub in different stages. Therefore,the development of Tamarix nabkha presents phased succession. Compared with ecological characteristics and nabkha shapes of Phragmites and Alaghi,Tamarix shrubs can more intensely perturb wind-borne sand movement on the ground because of its longer life expectancy,the rigid shoot lignified,stool germination easily with endurance to be buried by sand and resistance to deflation. The wind speed section at the top of Tamarix nabkha is different from nabkhas of Phragmites and Alaghi.