Characteristics of Water Consumption of Atraphaxis bracteata A. Los. in the Mu Us Sandy Land of North Central China.

Water consumption by Atraphaxis bracteata A. Los. was measured using sap flow measuring system from May to October in 2009, and environmental variables were measured simultaneously in this study,. The study revealed the sap flow rate was largest in June, and the daily sap flow was significantly affected by weather condition. The sap flow rate is related to stem diameter, stems with larger diameter had higher sap flow rate than smaller diameter stems. The effects of soil moisture at depths of <1 m on the sap flow rate were not significant, which may be related to the uptake of water by plants from deep soil. In addition, time lags of 30–130 minutes were observed between transpiration and increased sap flow. These time lags were related to stem size as well as water conditions. The ratio of nocturnal to diurnal sap flow normally varied in the range between 0.1 and 0.4; however, on rainy days, the ratio was even larger than 1.0, indicating that nocturnal sap flow results in significant water loss. Environment factors had significant effect on sap flow. Solar radiation and the vapor-pressure deficit had the largest effect on the sap flow rate during the day and at night, respectively. [ABSTRACT FROM AUTHOR]