Characteristics of Sap Flow of Quercus acutissima and Its Response to Environmental Factors in Laoshan Mountain

During May and October 2021, sample plot of 1 ha was established in artificial broad-leaved forest in Laoshan Natural Reserve of Shandong. 4 trees of Quercus acutissima were selected as sample tree for determination of DBH, height, crown width, sapwood area, and at meantime, the environment factors like temperature, humidity, pressure, wind speed, photosynthetic radiation and soil temperature was measured. Sap flow of Qu. acutissima was read by TDP sap flow meter. The result demonstrated that daily variation of sap flow was a unimodal curve. The peak and average sap flow were the highest in August. The sap flow was influenced by environment factors such as photosynthetically active radiation, saturation vapor pressure difference, air temperature, and relative humidity, with extremely significant （P<0.01）, especially photosynthetically active radiation. Multiple regression analysis resulted the regression equation of sap flow and environmental factors, with the decision coefficient R² of 0.747.