摘要：着重探讨了固定沙丘植物根系吸水问题。在甘肃省石羊河以东腾格里沙漠西南缘湖盆滩地邓马营湖北部一生长有白刺的固定沙丘上设置观测点，采用中子仪､负压计逐日定时分层测定沙丘0～175 cm深度含水量和水分势能。以野外实测数据为基础，运用数理统计方法确定非饱和导水率､水分扩散率等沙丘水分运动参数，并从宏观角度建立了与水面蒸发强度､沙丘水分含量相关的附加根系吸水项的白刺根系吸水模型。用所建数学模型对6月和8月白刺生长期内无雨时段沙丘水分动态进行模拟，并选取6月5日､10日､12日沙丘25 cm､55 cm和100 cm深度模拟含水量值与实测值进行比较分析，两者之间的相对误差为-21.97%～5.67%，大多在-0.016%～3.56%之间。同时，比较了秋季预测与实测沙丘剖面水分分布曲线。沙丘水分动态模拟结果的验证与分析表明：根系吸水率精度较高，能较正确反映无雨时段根系吸水规律；用所建数学模型预测的白刺生长期沙丘剖面含水量与实测值分布曲线拟合较好。
　　关键词：固定沙丘；根系吸水；数值模拟；水分预测
　　中图分类号：P641.13 文献标识码：A 文章编号：1672-1683(2007)05-0064-04
　　Study on the Numerical Simulation of Moisture Behavior in Fixed Dune under Water Extraction by Plant Roots
　　QIAN Ju LONG Xun-jian MA Jin-zhu ZHANG Hui-chang YI Li-xin2
　　(1.Key Laboratory of Western Chinas Environmental Systems，MOE，Lanzhou University，Lanzhou 730000，China；2.College of Environmental Science and Engineer，Nankai University，Tianjin 30007 China；*Author for correspondence)
　　Abstract： Water uptake by roots in fixed dune was discussed in this paper.The field experiments had been daily carried out on time within the 0 cm～175 cm depth of the fixed dune planted Nitraria tangutorum which is located in the north of Dengmaying basin at the southwestern edge of Tengger desert in Shiyanghe river basin in the northwestern Chinas Gansu province to measure moisture content and moisture potential with sand layers by Neutron moisture meter and Tensionmeter.Based on the measured data in the field，the parameters of dune moisture transport，such as unsaturated conductivity，moisture diffusivity etc.，were made using mathematical statistics method.
　　Then model with the item of water uptake by Nitraria tangutorum roots which was related to the rate of evaporation measured by evaporator and dune moisture contents was established at the macroscopic angle.In addition，the numerical simulations of moisture behavior in fixed dune during the growth of Nitraria tangutorum and rainless period in June and August were conducted.The relative errors between simulated data and measured ones were-21.97%～5.67%，mainly-0.016%～3.56%，which was indicated in the numerical simulation of dune moisture at the depth of 25 cm，55 cm and 100 cm on June 5 th，10 th and 12 th.Meantime，the predicted curves of moisture distribution and the measured ones in the dune profile in autumn were compared.The results from the verification and analysis of dune moisture simulated data showed that the precision of root uptake rate was higher，and it was able to indicate the regularity of water uptake during the rainless period，the predicted moisture distribution curve in the dune profile during Nitraria tangutorum growth season by the use of mathematical model was basically consistent with the measured one.
　　Keywords：fixed dune；water uptake by plant roots；numerical simulation；moisture prediction
　　
　　沙漠环境中，有限的大气降水是无灌溉条件下天然植被得以生存的主要水源之一。沙生植物对大气降水的吸收，主要通过沙丘水分来实现。根系是植物吸收水分的器官，根系吸水每时每刻都在发生。即使在植物叶片气孔关闭，无蒸腾水分逸出的夜间，根系仍以某一速率从沙丘中吸收少量水分以补充植株体白天过渡的水量损失，调节植物体内水分平衡^[1]。根系吸水是地下水—沙丘—植物—大气连续体(简称GSPAC)水分循环中的重要环节，也是植物与水分关系研究中的主要内容之一^[2-3]。沙丘温度､水分含量､水溶液浓度､通气状况及气象条件等GSPAC环境因素则会影响沙生植物根系吸水^[3-4]。沙丘含水量剖面分布不同时，对根系吸水在剖面上的分布有很大影响。如降水后，根系吸水的主要区域在沙丘浅层，沙层逐渐干燥时，根系吸水的区域开始向下运移^[1]。
　　

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