Simulation of crown leaf area index of Korean pine and broadleaved mixed forest in Changbai Mountains
长白山红松针阔叶混交林林冠层叶面积指数模拟分析

Based on the 3-year successive automatic measurement of photosynthetic active radiation above and under the crown of Korean pine and broadleaved mixed forest in Changbai Mountains, as well as the seasonal observation on leaf area index, a semi-empirical model was established to estimate the crown leaf area index of the forest. The results showed that this model could well reflect the seasonal variation of crown leaf area. From the comparison of 3-year leaf area index series, it was found that the date when the leaf area index began to rise was postponed if the date when its air temperature stably surpassed 0 degrees C came late. The dynamics of the leaf area index in whole growth season could be divided into three stages, i. e., rising, relatively stable, and dropping, and at each stage, there was a greater correlation between the leaf area index and the accumulated temperature above 0 degrees C, which could be expressed by Logistic curve and linear equation. The problems existing in the observation and estimation of forest crown leaf area index were discussed.