长白山红松针阔叶混交林林冠层叶面积指数模拟分析

根据长白山原始红松针阔叶混交林光合有效辐射的连续3年自动观测结果，结合便携式叶面积仪的季节观测，建立了以林冠上下光合有效辐射估算森林冠层叶面积指数的半经验公式.结果表明，该方法可以很好地反映叶面积的季节动态. 通过3年叶面积指数的季节动态比较发现，该森林冠层叶面积的起始生长日期随气温稳定通过0 ℃的日期延迟而延迟，整个生长季的叶面积动态可划分成上升期、相对稳定期和下降期，每个阶段都与大于0 ℃的积温存在较好的相关关系，分别用Logistic曲线和线性方程表达. 并对叶面积的观测和估算方法中存在的问题进行了讨论.

Simulation of crown leaf area index of Korean pine and broadleaved mixed forest in Changbai Mountains

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.