Patterns,magnitude,and controlling factors of hydraulic redistribution of soil water by Tamarix ramosissima roots

查看全文 作　　者：TengFei [1,2]YU;Qi [2,3]FENG;JianHua [2,3]SI;HaiYang [2,3]XI;Wei [2]LI

机构地区：[1]Research School of Arid Environment and Climate Change,Lanzhou University;[2]Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences;[3]Gansu Hydrology and Water Resources Engineering Research Center

出　　处：《Journal of Arid Land》索引2013年第5卷第3期,共12页

基　　金：supported by the Key Project of the Chinese Academy of Sciences (KZZD-EW-04-05);the National Natural Science Foundation of China (91025024);the Western Light Project of the Chinese Academy of Sciences 摘　　要：Tamarix spp.(Saltcedar)is a facultative phreatophyte that can tolerate drought when groundwater is not accessed.In addition to deep water uptake,hydraulic redistribution(HR)is another factor contributing to the drought tolerance of Tamarix spp.In this study,data on soil volumetric moisture content(θ),lateral root sap flow,and relevant climate variables were used to investigate the patterns,magnitude,and controlling factors of HR of soil water by roots of Tamarix ramosissima Ledeb.in an extremely arid land in Northwest China.Results showed evident diurnal fluctuations in θ at the depths of 30 and 50 cm,indicating 'hydraulic lift'(HL).θ increased remarkably at 10 and 140 cm but decreased at 30 and 50 cm and slightly changed at 80 cm after rainfall,suggesting a possible 'hydraulic descent'(HD).However,no direct evidence was observed in the negative flow of lateral roots,supporting HR(including HL and HD)of T.ramosissima.The HR pathway unlikely occurred via lateral roots;instead,HR possibly occurred through adventitious roots with a diameter of 2-5 mm and a length of 60-100 cm.HR at depths of 20-60 cm ranged from 0.01-1.77 mm/d with an average of 0.43 mm/d,which accounted for an average of 22% of the estimated seasonal total water depletion at 0-160 cm during the growing season.The climate factors,particularly vapor pressure deficit and soil water potential gradient,accounted for at least 33% and 45% of HR variations with depths and years,respectively.In summary,T.ramosissima can be added to the wide list of existing species involved in HR.High levels of HR may represent a considerable fraction of daily soil water depletion and substantially improve plant water status.HR could vary tremendously in terms of years and depths,and this variation could be attributed to climate factors and soil water potential gradient. 关键词：液压升降机土壤水分水分再分配控制因素柽柳人力资源气候因素水势梯度

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Patterns,magnitude,and controlling factors of hydraulic redistribution of soil water by Tamarix ramosissima roots

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