林分参数提取及与大气颗粒物分布关系

Extraction of forest stand spatial structure and its relationship with atmospheric particulate matter distribution

选取北京市奥林匹克森林公园紧邻五环道路的人工林作为实验样地,利用三维激光扫描系统获取林分的点云数据,分别通过体元模拟法和鱼眼图像的方法精确提取样地内树木的树冠体积和叶面积指数.采集获取样地的大气颗粒物浓度数据以及气象因子等数据,从林分空间结构参数的角度来分析林分空间结构对大气颗粒物的滞留能力.结果表明,对于大粒径颗粒物(2.5~100μm),不同季节时期的林分对其浓度影响为:夏季>春季>冬季.树冠体积和叶面积指数随季节的变化与大气颗粒物在林分中扩散的浓度变化量存在很大相关性.当树冠体积和叶面积指数变化率大时,林分对大气颗粒物的吸滞量相应增大,反之亦成立.

To investigate the regulatory function of forest spatial structure on retaining atmospheric particulate matter（PM）, point cloud data of forest park plantation were extracted using 3D laser scanning system in the ring road of Beijing Olympic Park. Then volume element simulation method and fish-eye method were applied to calculate tree canopy and leaf area index. Lastly, data on PM concentrations at different diameters and meteorological factors were interpreted. Results showed that retention capability of forest stand for PMs at diameter between 2.5 μm and 100 μm varied among seasons, with the highest adsorbability in summer and the lowest in winter. Canopy volume and leaf area index were highly correlated with PM concentrations, which larger canopy volume and leaf area index would attribute to higher rate of PM absorbed.