[1]Alax Desert Eco-hydrology Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China;
[2]Key Laboratory of Eco-hydrology of Inland River Basin, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China;
[3]Gansu Hydrology and Water Resources Engineering Research Center, Lanzhou, Gansu 730000, China;
evapotranspiration; eddy covariance; Populus euphratica Oliv. forest; Heihe River Basin;