Abstract: It is important to clarify the transpiration and water consumption of artificial vegetation for ecological construction in desertification area. In this study, we used thermal dissipation probe (TDP) and automatic weather stations to monitor longterm trunk sap flow of a poplar plantation and environmental factors in Horqin sandy land. We analyzed the dynamics of poplar sap flow and the relationship between sap flow and environmental factors. The results showed that the diurnal variation of sap flow generally followed a normal distribution, and occasionally a multi-peak curve. Weather conditions affected sap flow rate, with highest values on sunny days and lowest values on rainy days. In the growing season, sap flow rate was positively correlated with solar radiation intensity, saturated water vapor pressure difference and air temperature, with correlation coefficients R² of 0.88, 0.81 and 0.76, respectively. There was a negative correlation between sap flow rate and air relative humidity, with aR² of 0.79. The Penman-Monteith (P-M) model was constructed to simulate the potential evapotranspiration of poplar plantation and verified with the filed data. The results showed that the simulation effect was of high precision, with a R² of 0.83. Water consumption of poplar via evapotranspiration mainly depended on groundwater. The groundwater level dropped obviously accompanied by strong evapotranspiration of poplar during 9:00-18:00, after which groundwater level rose to some extent.

Key words: Horqin sandy land, poplar sap flow, environmental factor, Penman-Monteith model, groundwater level.