龙爪槐树干液流相对于气象因子的滞后效应分析

The sap flow velocity and the micro-meteorological environment of Sophora japonica f.pendula were measured from Aug.to Oct.2006 with sap flow gauge based on heat balance principle and auto-weather station in Ludong University.The time lag effect of sap flow compared to meteorological factors was analyzed,and the regressive analysis between comprehensive affecting factor put forward by principal component analysis and sap flow was conducted.The time lag effect analysis results showed that the sap flow lag effect existed compared to total solar radiation,wind speed and photosynthetically active radiation,and the lag time was 10 min,20 min and 10 min,respectively.The time lag effect was the reason of water storage adjustment of leaves,branches and trunks.The sap flow lag time to total solar radiation and photosynthetically active radiation was shorter than wind,because solar radiation affected tree transpiration directly,and the wind affected tree transpiration through affecting boundary resistance of leaves.In the case sap flow time lag considered or not,the determination coefficients between comprehensive meteorological affecting factor and sap flow were 0.830 and 0.944,respectively,and the determination coefficient ascending 13.735% because of lag effect considered.In conclusion,the fitted precision would be improved with the time lag effect of trunk sap flow compared to micro-meteorological factors considered.