Sap flow dynamic variations of Hippophae rhamnoides and its response of meteorological factors

In the present study, the sap flow of Hippophae rhamnoides and meteorological factors were measured in the Ulan Buh desertby using the TDP sap flow testing system and automatic meteorological station. The results showed that the daily variation curve of sap flow velocity in H. rhamnoides stem was in a multimodal distribution. The sap flow started at 07:50 and reached the maximum value around 09:10 which varied in a range of 292.07~340.27 g·h-1. The sap still flowed at night. The sap flow velocity in H. rhamnoides stem correlated with diameter and its daily accumulated sap flow amounts of diameter with 10.5, 8.3 and 7.5 cm was 16 593.26, 14 907.08 and 14 101.83 g, respectively. The change law of sap flow velocity was similar with that of environmental factors. The correlation analysis results revealed that the environmental factors affecting the variation of sap flow in H. rhamnoides were air relative humidity, air temperature, effective solar radiation, soil temperature in the depth of 10 cm and wind speed.