The leaf growth course of a Larix principis rupprechtii plantation located in North China is from the last ten day period of April to the first ten day period of June. Based on the data of actual measurement of six day typical sunny days in the period of leaf growth,the dynamic processes of light attenuation and light absorption in the different layers of forest canopy were determined and analyzed. In sunny days,the observed daily mean values of PAR transmitted through the canopy range from 30...