Effects of vegetation change on evapotranspiration in a semiarid shrubland of the Loess Plateau, China

Abstract. Vegetation change is a primary factor that affect evapotranspiration (ET), which is an important process in the hydrological cycle. In this study, an attempt is made to analyze the effects of vegetation change on ET using continuous observation data from eddy-covariance (EC) measurements over three periods (1 July 2011 to 30 June 2014) of a study site in a sparse shrubland study site located in the Loess Plateau of China, which is a fragile ecosystem experiencing serious soil desiccation. In our study, vegetation change includes phenological change and land use change. Phenological process of vegetation is validated to have a remarkable positive effect on ET in a rate of 1.83 ± 0.01 along with vegetation greening. Land use change at our study site was due to the native vegetation being cut-off by human activities, converting sparse shrubland to bare soil. With land use condition changing during the three years, annual total ET was observed to increase 103 mm, suggesting that soil evaporation consumes more water than canopy transpiration. In summary, the effects of vegetation change on ET suggest that both vegetation greening and increased area of exposed soil would aggravate the soil desiccation at our site in the north Loess Plateau.