Evapotranspiration and soil water relationships in a range of disturbed and undisturbed ecosystems in the semi-arid Inner Mongolia,China  

作　　者：Nan Lu Shiping Chen Burkhard Wilske Ge Sun Jiquan Chen 

机构地区：[1]Department of Environmental Sciences,University of Toledo,Toledo,OH 43606,USA [2]Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,18 Shuangqing Road,Beijing 100085,China [3]State Key Laboratory of Vegetation and Environmental Change,Institute of Botany,The Chinese Academy of Sciences,20 Xiangshan Nanxincun,Beijing 100093,China [4]USDA Forest Service Southern Research Station,920 Main Campus,Venture II Building,Suite 300,Raleigh,NC 27606,USA

出　　处：《Journal of Plant Ecology》2011年第1期49-60,共12页植物生态学报（英文版）

基　　金：Natural Science Foundation of China(30928002);National Aeronautics and Space Administration(NASA)-NEWS Program of US(NN-H-04-Z-YS-005-N);the Outstanding Overseas Scientists Team Project of CAS;the State Key Basic Research Development Program of China(2007CB106800);the National Basic Research Program of China(973 Program)(2010CB833501).

摘　　要：Aims Evapotranspiration(ET)is a key component of water balance and is closely linked to ecosystem productivity.In arid regions,large proportion of precipitation(PPT)is returned to the atmosphere through ET,with only a small amount available to plants.Our objective was to examine the variability in ET–soil water relationship based on a set of ecosystems that are representative for semi-arid Inner Mongolia and its main land use practices.Methods This study used Eddy covariance(EC)data of water vapor(i.e.ET,mm),PPT(mm),soil volumetric water content(VWC,%),root biomass density and soil properties from three paired sites in semi-arid Inner Mongolia:cropland(Cropland-D)versus undisturbed grassland(Steppe-D),grazed grassland(Grazed Steppe-X)versus fenced grassland(Fenced Steppe-X)and poplar plantation(Poplar-K)versus undisturbed shrubland(Shrubland-K).The paired sites experienced similar climate conditions and were equipped with the same monitoring systems.Important Findings The ET/PPT ratio was significantly lower at Cropland-D and Grazed Steppe-X in comparison to the undisturbed grasslands,Steppe-D and Fenced Steppe-X.These differences are in part explained by the lower VWC in the upper soil layers associated with compaction of surface soil in heavily grazed and fallow fields.In contrast,the ET/PPT ratio was much higher at the poplar plantation compared to the undisturbed shrubland because poplar roots tap groundwater.The VWC of different soil layers responded differently to rainfall events across the six study sites.Except for Poplar-K,ETwas significantly constrained by VWC at the other five sites,although the correlation coefficients varied among soil layers.The relative contribution of soil water to ET correlated with the density of root biomass in the soil(R2=0.67,P<0.01).The soil water storage in the upper 50 cm of soil contributed 59,43,64 and 23%of total water loss as ET at Steppe-D,Cropland-D,Shrubland-K and Poplar-K,respectively.Our across-site analysis indicates that the site level of soil water for ET dif

关 键 词：EVAPOTRANSPIRATION soil water storage land use Inner Mongolia semi-arid region eddy-flux measurements 

分 类 号：S15[农业科学—土壤学]