Responses of nighttime sap flow to atmospheric and soil dryness and its potential roles for shrubs on the Loess Plateau of China  

作　　者：Weiwei Fang Nan Lu Yu Zhang Lei Jiao Bojie Fu 

机构地区：[1]State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]School of Natural Resources,Faculty of Geographical Science,Beijing Normal University,Beijing 100875,China [4]College of Tourism and Environment,Shaanxi Normal University,Shaanxi 710119,China

出　　处：《Journal of Plant Ecology》2018年第5期717-729,共13页植物生态学报（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(No.41390462 and 41230745);the Project of Social Science Youth Foundation of Beijing Municipal(No.15JGC148).

摘　　要：Aims Nocturnal sap flow(E_(night))has been observed in a variety of plant species and environmental conditions.In water-limited environ-ments,E_(night) is important in the regulation of plant water’s physi-ology.This study was designed to evaluate the way in which E_(night)(defined as sap flow from 20:30 to 06:00)responded to changes in the atmospheric vapor pressure deficit(VPD)and the soil water con-tent(SWC),and explored its potential physiological significance for different plant species in a semi-arid area.Methods We selected three shrub species:Vitex negundo L.(VN),Hippophae rhamnoides L.(HR)and Spiraea pubescens Turcz(SP)in the semi-arid Loess Plateau of China.The plots of the three communities dominated by each of three species were on the same hill slope.Half-hourly sap flow density was measured in six to seven sample stems for each species during the main grow-ing season(June to August 2015).VPD,SWC,leaf water potential(Ψleaf)and stomatal conductance(G_(s))were measured at the same time.Regression analyses were conducted to determine the rela-tionships between E_(night),E_(day),E_(night)/E_(daily),VPD and SWC at half-hourly and daily time scales,as well as between E_(night),E_(day) andΨleaf.Important Findings The mean values of E_(night) and E_(day) were higher,but E_(night)/E_(daily) val-ues were lower for VN compared to HR and SP.The responses of sap flow density to VPD and SWC varied at different temporal scales.VPD was the dominant factor that affected E_(night) and E_(day) at the half-hourly scale for all three species.In contrast,SWC was the key factor that influenced E_(day) at the daily time scale.The values of E_(day) and E_(night)/E_(daily) correlated negatively with SWC because the effect of SWC was stronger on E_(day) than on E_(night).Although the low fraction of E_(night)/E_(daily)(4%-7%)may indicate a minor short-term effect of E_(night) on the standing water balance,E_(night) had eco-physiologically significance to the plants.The discrepancy inΨleaf between sunset and the following

关 键 词：nocturnal sap flow stem refilling stomatal conductance leaf water potential Loess Plateau 

分 类 号：H31[语言文字—英语]