Soil moisture dynamics in an artificially re-vegetated desert area
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摘要: 研究土壤水分动态有助于在水文过程与生态格局之间建立定量的联系。以大型自动称重式蒸渗仪为试验设施,对草原化荒漠带固沙植丛区与无植被沙区土壤水分动态及蒸散发进行对比研究。结果表明,观测期内植丛区及无植被沙区土壤水分变化均与降水过程高度相关,油蒿与柠条植丛区总蒸散量大体相当,平均蒸散速率分别为1.31mm/d,1.22mm/d。受固沙植物种生育期差异与降水年内分配变化的综合影响,当经历连续30多天无雨期时,柠条植丛区土壤水分骤降,根系密集区土壤体积含水率降低至0.5%以下,平均蒸散速率由前期的2.2mm/d降至0.6mm/d。油蒿植丛区土壤体积含水率在1%左右变化,平均蒸散速率由1.8mm/d降为0.9mm/d,仍高于柠条植丛区达50%。无植被沙区土壤体积含水率保持在大于2%的水平,平均蒸发速率由1.1mm/d减小至0.4mm/d,平均为0.78mm/d,约为植丛区平均蒸散速率的60%。土壤深层渗漏量达113.4mm,占降水量的40.5%,渗漏速率平均为0.63mm/d。人工固沙植被有效地利用了这部分降水资源,使得植丛区土壤水分无深层渗漏。Abstract: The study on soil moisture dynamic is instrumental in establishing the quantitative linkage between hydrologic dynamics and ecological patterns and processes.The experiment based on the auto-weighing lysimeters aims to study the soil moisture dynamics and evapotranspiration (ET) of revegetated and bare desert dune area.The results reflect that during the experimental periods between March 31 and October 21, 2002, the soil moisture dynamics is highly related to the individual rainfall events, the areas of Artemisia ordosica Krasch and Caragana korshinskii Kom vegetation have a grossly equal magnitude in overall ET through the growing period, and the daily ET is 1.31 mm/d and 1.22 mm/d, respectively.The soil moisture decreases greatly in the Caragana korshinskii kom vegetation during the non-rainfall time for more than one month, especially within the soil profile of plant root concentration depth of 40-60 cm and 100-140 cm.After a long time of intra storm period, the ET rate of Artemisia ordosica vegetation decreases from the former value of 1.8 mm/d to 0.9 mm/d, the corresponding values of Caragana korshinskii kom vegetation and the bare desert dune area are from 2.2 mm/d to 0.6 mm/d and from 1.1 mm/d to 0.4 mm/d, respectively.To the overall deep drainage from the bare desert area, it accounts for 113.4 mm.Hence, the order of magnitude of annual rainfall fraction (40.5%) turned into groundwater recharge for similar areas varies between 0 and 50%, which has been shown by some previous investigators.Consequently, the results of this study fit the situation in the high middle of this interval.The artificial re-vegetation uses this part of precipitation effectively by eliminating the deep infiltration.
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