Comparison of the Vegetation Effect on ET Partitioning Based on Eddy Covariance Method at Five Different Sites of Northern China

Vegetation exerts profound influences on evapotranspiration (ET) partitioning. Many studies have demonstrated the positive impact of vegetation cover on the ratio of transpiration (T) to ET. Whether it is universally true with regard to different vegetation types and different sites is understudied. In this study, five sites in Northern China with different vegetation types were selected for comparison study. ET partitioning is conducted using an approach based on the concept of the underlying water use efficiency with eddy covariance measurements. The results show various patterns of vegetation’s effects over ET partitioning and, when compared with existing studies, also reveal a new relationship between the T/ET ratio and Normalized Difference Vegetation Index (NDVI) at some of the sites. At the alpine meadow site, the T/ET ratio gradually increase when NDVI is low and rapidly increase as NDVI go beyond a certain value, whereas at the arid shrub site, the T/ET ratio rapidly increase when NDVI is low and plateaus at a certain value when NDVI reaches a relatively high value. In deciduous forest, the T/ET ratio becomes unresponsive to NDVI beyond a threshold value. This study also reveals that irrigation schemes play a major role in determining the correlation between the T/ET ratio and NDVI because the T/ET ratio becomes well correlated with NDVI in case of flood irrigation and irrelevant to NDVI in the case of mulch drip irrigation. Furthermore, this study helps us to understand ET partitioning under different sites and different human activities such as irrigation. These findings can help policymakers to better understand the connection between vegetation and climate change or human activities and provide significant information for water management policy.

[1]  Kelly K. Caylor,et al.  Partitioning evapotranspiration across gradients of woody plant cover: Assessment of a stable isotope technique , 2010 .

[2]  Ü. Rannik,et al.  Gap filling strategies for defensible annual sums of net ecosystem exchange , 2001 .

[3]  Xuhui Lee,et al.  Evapotranspiration partitioning through in-situ oxygen isotope measurements in an oasis cropland , 2016 .

[4]  W. P. Kustasb,et al.  Fluxpart: Open source software for partitioning carbon dioxide and water vapor fluxes , 2018 .

[5]  Russell L. Scott,et al.  Evapotranspiration partitioning in semiarid shrubland ecosystems: a two‐site evaluation of soil moisture control on transpiration , 2011 .

[6]  H. Dehghanisanij,et al.  A Bowen Ratio Technique for Partitioning Energy Fluxes between Maize Transpiration and Soil Surface Evaporation , 2008 .

[7]  A-Xing Zhu,et al.  Evapotranspiration partitioning using an optimality-based ecohydrological model in a semiarid shrubland , 2018, Int. J. Digit. Earth.

[8]  Pei Wang,et al.  Partitioning evapotranspiration in a temperate grassland ecosystem: Numerical modeling with isotopic tracers , 2015 .

[9]  F. Tian,et al.  Soil salt distribution under mulched drip irrigation in an arid area of northwestern China , 2014 .

[10]  T. Scanlon,et al.  On the correlation structure of water vapor and carbon dioxide in the atmospheric surface layer: A basis for flux partitioning , 2008 .

[11]  Wonsik Kim,et al.  Partitioning of evapotranspiration using high‐frequency water vapor isotopic measurement over a rice paddy field , 2015 .

[12]  John Bjørnar Bremnes,et al.  Probabilistic wind power forecasts using local quantile regression , 2004 .

[13]  D. G. Meadows,et al.  Variability of soil physical and hydraulic properties at the Mojave Global Change Facility, Nevada: Implications for water budget and evapotranspiration , 2009 .

[14]  Yanlian Zhou,et al.  Water use efficiency of China’s terrestrial ecosystems and responses to drought , 2015, Scientific Reports.

[15]  F. Tian,et al.  Partitioning of Cotton Field Evapotranspiration under Mulched Drip Irrigation Based on a Dual Crop Coefficient Model , 2016 .

[16]  Shaomin Liu,et al.  A comparison of eddy-covariance and large aperture scintillometer measurements with respect to the energy balance closure problem , 2011 .

[17]  Russell L. Scott,et al.  Partitioning evapotranspiration using long‐term carbon dioxide and water vapor fluxes , 2017 .

[18]  Kelly K. Caylor,et al.  δ2H isotopic flux partitioning of evapotranspiration over a grass field following a water pulse and subsequent dry down , 2014 .

[19]  Bofu Yu,et al.  Partitioning evapotranspiration based on the concept of underlying water use efficiency , 2016 .

[20]  H. Lambers,et al.  Partitioning of evapotranspiration in a semi-arid eucalypt woodland in south-western Australia , 2009 .

[21]  C. Boast,et al.  A ``Micro-Lysimeter'' Method for Determining Evaporation from Bare Soil: Description and Laboratory Evaluation1 , 1982 .

[22]  Jake F. Weltzin,et al.  Dynamics of transpiration and evaporation following a moisture pulse in semiarid grassland: A chamber-based isotope method for partitioning flux components , 2005 .

[23]  M. Migliavacca,et al.  Basic and extensible post-processing of eddy covariance flux data with REddyProc , 2018, Biogeosciences.

[24]  R. Scott,et al.  Invasion of shrublands by exotic grasses: ecohydrological consequences in cold versus warm deserts , 2012 .

[25]  X. Lee,et al.  Evapotranspiration partitioning for three agro-ecosystems with contrasting moisture conditions: a comparison of an isotope method and a two-source model calculation , 2017 .

[26]  Dan Yakir,et al.  Effects of spatial variations in soil evaporation caused by tree shading on water flux partitioning in a semi-arid pine forest. , 2010 .

[27]  X. Lee,et al.  Partitioning of evapotranspiration through oxygen isotopic measurements of water pools and fluxes in a temperate grassland , 2014 .

[28]  R. Dickinson,et al.  A review of global terrestrial evapotranspiration: Observation, modeling, climatology, and climatic variability , 2011 .

[29]  H. R. Gardner,et al.  Direct evaporation from soil under a row crop canopy , 1983 .

[30]  S. Uhlenbrook,et al.  Experimental investigations of water fluxes within the soil–vegetation–atmosphere system: Stable isotope mass-balance approach to partition evaporation and transpiration , 2010 .

[31]  Stephen P. Good,et al.  Global synthesis of vegetation control on evapotranspiration partitioning , 2014 .

[32]  S. Kanae,et al.  Global Hydrological Cycles and World Water Resources , 2006, Science.

[33]  W. Schlesinger,et al.  Transpiration in the global water cycle , 2014 .

[34]  M. S. Moran,et al.  Partitioning evapotranspiration in semiarid grassland and shrubland ecosystems using time series of soil surface temperature , 2009 .

[35]  Naftali Lazarovitch,et al.  A review of approaches for evapotranspiration partitioning , 2014 .

[36]  Qing Xiao,et al.  Heihe Watershed Allied Telemetry Experimental Research (HiWATER): Scientific Objectives and Experimental Design , 2013 .

[37]  S. J. Birks,et al.  Terrestrial water fluxes dominated by transpiration , 2013, Nature.

[38]  Mario Minacapilli,et al.  Combined use of eddy covariance and sap flow techniques for partition of ET fluxes and water stress assessment in an irrigated olive orchard , 2013 .

[39]  R. Maxwell,et al.  Connections between groundwater flow and transpiration partitioning , 2016, Science.

[40]  R. Scott,et al.  Partitioning of evapotranspiration and its relation to carbon dioxide exchange in a Chihuahuan Desert shrubland , 2006 .

[41]  Dennis D. Baldocchi,et al.  A comparison of methods for determining forest evapotranspiration and its components: sap-flow, soil water budget, eddy covariance and catchment water balance , 2001 .

[42]  Peter E. Thornton,et al.  The Partitioning of Evapotranspiration into Transpiration, Soil Evaporation, and Canopy Evaporation in a GCM: Impacts on Land–Atmosphere Interaction , 2007 .

[43]  M. Vauclin,et al.  Partitioning evapotranspiration fluxes into soil evaporation and plant transpiration using water stable isotopes under controlled conditions , 2010 .

[44]  Tsutomu Yamanaka,et al.  Application of a two‐source model for partitioning evapotranspiration and assessing its controls in temperate grasslands in central Japan , 2014 .

[45]  Diego G. Miralles,et al.  Revisiting the contribution of transpiration to global terrestrial evapotranspiration , 2017 .

[46]  F. Tian,et al.  A comparison of methods for determining field evapotranspiration: photosynthesis system, sap flow, and eddy covariance , 2013 .

[47]  Thomas J. Sauer,et al.  Micro-Bowen ratio system for measuring evapotranspiration in a vineyard interrow , 2013 .

[48]  W. Kustas,et al.  Partitioning Evapotranspiration Using an Eddy Covariance‐Based Technique: Improved Assessment of Soil Moisture and Land–Atmosphere Exchange Dynamics , 2012 .

[49]  H. Guan,et al.  Environmental and physiological controls on sap flow in a subhumid mountainous catchment in North China , 2017 .

[50]  A. Strahler,et al.  Monitoring vegetation phenology using MODIS , 2003 .

[51]  W. Oechel,et al.  FLUXNET: A New Tool to Study the Temporal and Spatial Variability of Ecosystem-Scale Carbon Dioxide, Water Vapor, and Energy Flux Densities , 2001 .

[52]  Tetsuo Sakuratani,et al.  A heat balance method for measuring water flux in the stem of intact plants , 1981 .

[53]  Martha C. Anderson,et al.  The future of evapotranspiration: Global requirements for ecosystem functioning, carbon and climate feedbacks, agricultural management, and water resources , 2017 .

[54]  Dan Yakir,et al.  Dynamics of evapotranspiration partitioning in a semi-arid forest as affected by temporal rainfall patterns , 2012 .

[55]  Mark A. Weltz,et al.  Partitioning evapotranspiration in sparsely vegetated rangeland using a portable chamber , 2006 .

[56]  Bing Liu,et al.  The response of sap flow in shrubs to rainfall pulses in the desert region of China , 2010 .

[57]  Bing Liu,et al.  Evapotranspiration partitioning, stomatal conductance, and components of the water balance: A special case of a desert ecosystem in China , 2016 .