The sap flow velocity of Populus euphratica with different DBH had different seasonal rules, for DBH is 60cm and 28cm, velocity was bigger in May then in August, while for 15cm, velocity in August was bigger;

• 不同胸径胡杨流速具有不同季节变化规律,60cm和28cm胡杨液流速率均5月>8月,而15cm的8月>5月。