毛乌素沙地三种荒漠灌木根系分布特征与土壤水分研究

用全根系挖掘法，调查研究了风沙地生境中的黑沙蒿、杨柴、沙木蓼的根系分布特征；对根际不同土层土壤水分含量进行了观测，确定3种植物根系分布和土壤水分的响应特征。结果表明:杨柴的根系分布范围为地下0-280cm，主要分布在20-110cm，占总根重的65.86%；沙木蓼的根系分布范围0-180 cm，主要分布在0-80cm，占总根重的68.29%；黑沙蒿的根系分布范围0-240cm，主要分布在0-60cm，占总根重的62.14%。3种不同植物根系垂直分布形态特征，杨柴为“V”型分布，黑沙蒿为“伞”型分布，相比之下沙木蓼分布比较均匀。各土层中，除杨柴0-20cm土层根系分布较少外，黑沙蒿和沙木蓼表层根系分布较多；0-60cm土层中分布的根系密度最大，均表现为从土壤表层到深层逐次递减趋势；植物根系分布对土壤水分的响应显著，根系集中分布区域土壤含水量明显减小；黑沙蒿根际平均土壤水分含量最大，沙木蓼次之，杨柴最小，其与根系分布、水分利用策略密切相关。在水分资源竞争中，植物根系分布特征起到重要的作用。

Root Distribution of Three Desert Shrubs and Soil Moisture in Mu Us Sand Land

Root distribution of three desert shrubs,Artemisiaordo-sica,Hedysarum mongolicum and Atraphaxis bracteata A· Los· were investigated in wind sandy land conditions using whole root system excavation method.The rhizosphere soil moisture contents in different layers were observed to determine the root distribution of three desert shrubs and their jnteractive of soil moisture.The results showed that roots of Hedysarum mongolicum distribution for underground 0-280cm,mainly distributed in the 20-110 cm,and their root weight is 65.86% of the total amounts.The roots of Atraphaxis bracteata A· Los· distribution for underground 0-180cm,mainly distributed in the 0-80cm,and their weight is 68.29% of the total amounts.The roots of Artemisiaordo-sica distribution for underground 0-180 cm,mainly distributed in the 0-60cm,and their weight is 62.14% of the total amounts.For vertical distribution of plant root systems of three different morphological characteristics,the distribution of Atraphaxis bracteata A· Los· is the "V"-type,and the distribution of Artemisiaordo-sica is "umbrella" type.In contrast,the distribution of Atraphaxis bracteata A· Los· is more uniformly.Except for Hedysarum mongolicum,Artemisiaordo-sica and Atraphaxis bracteata A· Los· have more root distributing in toplayer (0-20cm).There are largest distribution share in 0-80cm layer of root density,and decreasing trend from the soil surface to the deep layers.The absorptive roots of plant have markedly effect on soil moisture.Soil moisture rapidly decreased under the concentrated distribution area of absorptive roots.The largest soil water content is Artemisiaordo-sica,the next is Atraphaxis bracteata A· Los· and Hedysarum mongolicum.The plant responses is closely related to their root distribution and plant water-use strategy.The discrepancy of root distribution partially determined the position of the studied species in water resources competition.