中文摘要：

蒙古栎（Quercus mongolica）、花曲柳（Fraxinus rhynchophulla）和胡桃楸（Juglans mandshurica）林是我国东北天然次生林区具有代表性的主要林型。本研究以该3种林型为对象，利用数码相机外带鱼眼镜头获得3种林型的半球面影像，再利用专用软件GapLight Analyzer处理分析获得了叶面积指数、林冠孔隙度和林下光照因子等参数。结果表明，3种林型的叶面积指数变化总体趋势是一致的，均呈先上升再下降的单峰曲线，蒙古栎林和胡桃楸林都是在7月中旬或8月中旬达到最大峰值，花曲柳林是在8月中旬或9月中旬达到最大峰值；3种林型冠层孔隙度的变化总体趋势也是一致的，呈先下降再上升的单峰曲线，不同样地峰值出现的时间也不同，最低峰值在6、7、8、9月中旬均有出现；通过对不同月份的叶面积指数、林下散射光、林下直射光的变异系数分析表明，7-9月叶面积指数的空间格局是影响林下散射光空间分布的主要因素。叶面积指数与林冠孔隙度呈指数相关。

英文摘要：

Quercus mongolica, Fraxinus rhynchophulla, and Juglans mandshurica forests are the representative forest types in natural secondary forest zone of northeast China. By using digital camera with fish-eye lens, the hemispherical photographs of the three forest types were taken, and the parameters leaf area index, canopy porosity, and illumination factors were analyzed by Gap Light Analyzer. For the leaf area index of the three forest types, there was a similar variation trend, i. e. , increased first and decreased then, with the maximum presented in mid-July or August for Q. mongolica and J. mandshurica forests while in mid-August or September for F. rhynchophulla forest. The canopy porosity of the three forest types also had a similar variation trend; but opposite to leaf area index, being decreased first and increased then, with the minimum presented in mid-June, July, August or September. The analysis of variation coefficients of leaf area index, transmitted direct gap light, and transmitted diffuse gap light indicated that the spatial pattern of leaf area index in July-September was the main factor affecting the spatial distribution of transmitted diffuse gap light. Leaf area index had an exponential regression relationship with canopy porosity.