荒漠绿洲土壤优先流研究进展

A Review of Researches on Preferential Flow in Desert-oasis Region

荒漠绿洲土壤受干湿交替、冻融作用和土壤特性等非生物因素和动物洞穴、植物根系生物因素影响,存在大孔隙。水分和溶质优先沿着相互连通的大孔隙快速补充到土壤深层或浅层地下水,引起绿洲农田水分、养分损失;大孔隙存在,增强了土壤通气性,促进农田地力提升。荒漠绿洲土壤优先流的发生,减少地表径流及其侵蚀,促进水分入渗,影响着干旱区植被恢复和地下水补给。重点分析影响荒漠绿洲土壤优先流的非生物和生物因素,综述优先流对该区土壤性质和水文要素的影响。未来该区研究应重视以下几个方面:(1)加强大孔隙三维空间构型的研究,分析大孔隙结构与土壤优先流发生的内在机制;(2)开展不同景观类型土壤优先流的野外监测,认识土壤优先流的运动规律,揭示荒漠绿洲土壤优先流与植被互馈机制;(3)发展并构建荒漠绿洲土壤优先流运动的动力学模型。

Soil macropores are formed under the joint effect of abiotic factors（wetting and drying alternation,freezing and thawing processes,and soil properties,etc.）and biotic factors（soil fauna burrows,plant root channels）in desert-oasis region.As they may act as pathways for preferential flow,water and solute migrate rapidly along preferential pathways to shallow groundwater,which enhance the risks of water and nutrient loss.The presence of soil macropores also enhances soil ventilation,promotes nutrient cycling,and improves soil fertility.Preferential flow occurrence reduces surface runoff and its erosion,promotes water infiltration,and affects vegetation restoration and groundwater recharge.This paper analyzes the generated causes of preferential flow and its effect on pedologic and hydrological processes in desert-oasis ecosystems.Combined with the current research progress,the research emphases in the future are put forward as follows：（1）more efforts should be dedicated to conducting in situ field study of soil macropore networks and its effect on preferential flow;（2）Field experiments are conducted to analyze preferential flow movement in different landscapes and to reveal the interaction mechanism of preferential flow and vegetation;（3）the model is developed to simulate the movement of preferential flow in desert-oasis region.