Abstract: DYNAGAGE packaged sap flow system produced in DYNAMAX company of America and MONITOR auto weather station were applied to measure the sap flow flux of trunk and micro-environmental meteorological factors from 20th August to 21st September in Ludong University,and the sap flow and micro-environmental meteorological data were analyzed with the principal components analysis method.Results showed that the environmental factors affected trunk sap flow could be divided into two principal components,the solar radiation and the atmospheric humidity.The comprehensive effect factors were highly related to the sap flow flux by the regression analysis.The coefficient of determination was 0.867.The result of regression analysis of comprehensive environmental factor with sap flow flux was compared with total solar radiation,photosynthesis available radiation,air temperature,relative humidity and wind speed.Results showed that comprehensive environmental factor was a reasonable index for sap flow flux's predicting in short time.

Key words: Principal components analysis, Principal components analysis, Sap flow flux, Meteorological factor, Comprehensive environmental factor, Regressive analysis