| The lag effect of sap flow compared to meteorological factors was analyzed, and the multiple linear regression and the stepwise regression methods were applied to fit sap flow velocity, and the change of fitted precision was compared before and after sap flow lag effect considered. The lag effect analysis results showed that the sap flow lag effect existed compared to total solar radiation, wind speed and photosynthesis available radiation, the lag times were 10 min, 20 min and 10 min, respectively. The results of multiple linear regression and stepwise regression showed that the determination coefficient and the slop of fitted line were high with sap flow lag effect considered, and the relative error between fitted values and measured values was low. In conclusion, the fitted precision of sap flow velocity with lag effect considered was high. |
