古尔班通古特沙漠西南缘柽柳沙包土壤粒度分布特征

Distribution Pattern of Soil Grain Size in Tamarix Sand Dune in the Southwest of Gurbantunggut Desert

柽柳(Tamarix chinensis)沙包是古尔班通古特沙漠地区特殊的生物地貌景观,对维持区域生态环境稳定具有重要作用。采用野外调查与室内分析相结合的方法,对古尔班通古特沙漠西南缘柽柳沙包0—500 cm层土壤粒度特征进行分析。结果表明:(1)该地区柽柳沙包土壤粒度组成以细粒物质为主,其中粉粒含量最高,其次为极细沙粒,两者含量达到80%以上,且50μm以下土壤粒度含量在57%以上。(2)随着土层深度的增加,黏粒、粉粒、平均粒径及分形维数总体呈先升高后降低再升高的变化趋势,极细沙粒、细沙粒及分选系数总体呈先降低后升高再降低的变化,土壤总体分选性较差,偏度呈正偏态,峰态呈中等峰态。分形维数、平均粒径与黏粒、粉粒呈显著正相关,与极细沙粒、细沙粒呈显著负相关,表明分形维数和平均粒径能够较好地反映柽柳沙包土壤粒度组成特征。(3)柽柳沙包土壤粒度的形成受土壤含水量、pH、全磷、有机质及电导率等土壤特性的影响。研究结果表明,平均粒径和分形维数能够较好地反映柽柳沙包土壤粒度分布特征,柽柳沙包土壤粒度组成是荒漠—绿洲过渡带土壤形成中不可忽视的潜在物质基础。

Tamarix chinensis sand dunes are specific bio-geographical landscape in Gurbantunggut Desert,which play an important role in maintaining the stability of regional ecological environment.Based on field investigation and indoor analysis,the soil grain size characteristics of 0—500 cm soil layer in T.chinensis sand dunes in the southwest of Gurbantonggut Desert were analyzed.The results showed that:(1)Soil grain size composition of T.chinensis sand dunes was dominated by silt and very fine sand,and the content was more than 80%,furthermore,the content of soil particle below 50μm accounted for more than 57%.(2)With the increasing soil depth,the content of clay and silt,average particle size and sorting coefficient showed the trend of increase-decrease-increase.In general,the content of very fine sand and fine sand,skewness and kurtosis showed the trend of decrease-increase-decrease.The overall sorting ability of soil was poor.Kurtosis was generally mesokurtic peak,and the grain size distribution was positive skewness.The fractal dimension and average particle size were significantly positively correlated with clay and silt,and negatively correlated with very fine sand and fine sand,indicating that fractal dimension and average particle size could better reflect the characteristics of soil particle size composition of T.chinensis sand dunes.(3)Soil particle size of T.chinensis sand dunes was affected by soil water content,pH,total phosphorus,organic matter and electrical conductivity.The average particle size and fractal dimension could well reflect the characteristics of soil particle distribution in the profile of T.chinensis sand dunes,and soil grain size composition of T.chinensis sand dunes was a potential material basis for soil formation in the desert-oasis transition zone.