【摘要】 [目的]研究对农田有重要防护作用的农田防护林在农田节水灌溉模式下的水分利用机制,为本地区农田和农田防护林的优化灌溉提供参考。[方法]利用稳定氧同位素(δ¹⁸ O)研究干旱绿洲区常见农田防护林胡杨（Populus euphratica）、沙枣（Elaeagnus angustifolia）和榆树（Ulmus pumila）在农田节水灌溉模式下的水分利用机制,根据直接判断法、IsoSource模型和吸水深度模型3种方法对结果进行了对比分析。[结果]不同时间,不同树种防护林水分利用来源不同。其中4月胡杨主要使用10—20cm的浅层土壤水,贡献率为83.3%;沙枣主要使用80—120cm和120—160cm的深层土壤水,其贡献率分别为50.6%和16.9%;榆树主要使用50—300cm的深层土壤水和地下水,累计贡献率为82.5%;5月胡杨主要利用浅层0—30cm的土壤水,贡献率为57.1%;沙枣和榆树转而利用表层0—10cm的土壤水,其贡献率分别为50.8%和52.7%;6月胡杨利用0—20cm浅层土壤水和地下水,贡献率分别为38.7%和10.5%;沙枣有76.9%的水分来源于10—20cm的浅层土壤;榆树主要水分来源中有49.1%来自于0—80cm,另有12.3%来自于地下水。同时研究得出胡杨4—6月的平均吸水深度分别为18,28,25cm,沙枣的平均吸水深度分别为118,37,34cm;榆树的平均吸水深度分别为95,37,29cm。[结论]选择农田防护林树种时,在保证防护林防护效益的同时,应选择搭配以深层土壤水或地下水为主要水分来源的种类,从而更加高效地发挥农田防护林的防护作用。更多还原

【Abstract】 [Objective]This paper studied the water use mechanism of farmland shelterbelts with important protection function under the mode of farmland water-saving irrigation,in order to provide a scientific basis for optimizing irrigation of the local farmland and farmland shelterbelt.[Methods]The stable oxygen isotope(δ¹⁸ O)was used to study the water use mechanism of Populus euphratica,Elaeagnus angustifolia and Ulmus pumilain the arid oasis areas under farmland water-saving irrigation mode.The results were compared and analyzed based on the direct judgment method,IsoSource model and water absorption depth model.[Results]The sources of water use was different for different tree species at vary time.In April,P.euphratica mainly used 10—20 cm of shallow soil water,and its contribution rate was 83.3%.E.angustifolia mainly used deep soil water at 80—120 cm and 120—160 cm depth with contribution rates of 50.6% and 16.9%,respectively.Whereas,82.5% water usage of U.pumila was from 50—300 cm depth of soil water and groundwater.In May,57.1% of water used by P.euphratica was from 0—30 cm shallow soil water.Surface soil water at 0—10 cm soil depth contributed 50.8% and 52.7% for the water usage of E.angustifoliaand U.pumila,respectively.In June,the contribution of water source for P.euphratica usage was 38.7% from 0—20 cm shallow soil,while 10.5% from groundwater.And 76.9% of the water content of E.angustifoliacame from shallow soil of 10—20 cm,49.1% of water usage for U.pumila came from 0—80 cm soil,and another 12.3% from groundwater.The average water absorption depth of P.euphratica was 18,28,25 cm,respectively in April,May and June.For E.angustifolia,it was 118,37,34 cm,respectively.At the same time,it was95,37,29 cm for U.pumila,respectively.[Conclusion]When selecting farmland shelterbelt tree species,while ensuring the protection benefit of shelterbelt,we should choose the species with deep soil water or groundwater as the main water source,so as to exert the protective effect of farmland shelterbelt more efficiently.更多还原