辽东次生林典型林分三维绿量转换叶面积研究

Scaling is one of the important scientific problems in ecology. Precision calculation of leaf area index (LAI) is the key for scaling and functional quantification of forest ecosystem. The study will take the typical stands of secondary forest in eastern Liaoning as research object. The tree canopy will be subarea based on light heterogeneity in tree canopy and light adaptation of tree species, and then establish a digital 3-dimensional subarea system of canopy with the aid of computer simulation technology. Canopy volume of subarea is extracted from the system and leaf area in the subarea is to be calculated by measuring living leaf one by one in the field. Canopy volume and leaf area of foliage, tree species and forest canopy will be obtained by adding and weighted adding. Quantification relationship between canopy volume and leaf area in tree species-level and canopy-level will be simulated. Conversion of leaf area to effective leaf area is analyzed and calculated. The results can be used to not only develop base for precision calculation of forest LAI and canopy functional quantification but also provide revised parameter of forest LAI in large forest area obtained by using Light Detection And Ranging(LiDAR) data and forest LAI obtained by plant canopy analysis system. It has the important scientific significance as well as the broad application prospect.

尺度转换是生态学研究的重要问题之一，叶面积指数(1eaf area index，LAI)精准估算是森林生态系统尺度转换和功能量化的关键。本研究拟以辽东次生林典型林分为研究对象，基于树冠内光异质性和树种光适应性对树冠进行分区，进一步借助计算机仿真技术，建立三维数字化树冠分区系统，在此基础上，提取分区树冠的三维绿量，野外活体实测树冠分区叶面积，通过简单累加和权重累加的方法获得单株、树种和冠层层次的三维绿量和叶面积，进而拟合树种和冠层两个层次三维绿量和叶面积的量化关系，解析叶面积和有效叶面积的转化关系，研究结果不仅能为实现森林叶面积指数和冠层功能高精度估算奠定理论基础，还能为应用激光雷达技术通过三维绿量大面积反演森林叶面积提供转换参数，为冠层分析系统测量叶面积指数提供校正系数，具有重要的科学意义和广阔的应用前景。

通过本研究，开展了基于激光雷达技术（LiDAR）的树木关键特征因子的提取与验证，获取了树木关键特征因子的提取方法，精度达到98%（α=0.05）和97%（α=0.01）以上；获取了利用LiDAR测算树木三维绿量的过程与方法，并通过多项对比分析，确立了获取LiDAR测算树木三维绿量的高精度便捷测算方法-点云分布填充式重建树冠三维绿量。对比当前主要叶面积测算方法，开创性的提出了一种更为高效快速便捷的叶面积快速提取法-Digimizer数字图像法，批量快速测算树木叶面积；基于LiDAR开展了多种树冠叶面积的模拟和树木生物量的模拟，确认了三种有效的树冠叶面积模拟方式：基于三维绿量的叶面积模拟、基于枝条基径的叶面积模拟和基于多特征因子融合叶面积模拟，两种树木生物量模拟方式：基于枝条因子的生物量模拟和基于三维绿量的生物量模拟，可以应对不同的需求实现相应高精度、快速便捷的获取树冠叶面积和树木生物量。利用树冠叶面积的实测与模拟，开展了相应区域树种的冠层叶面积与仪器测量LAI的比较，并开展了初步的仪器测量LAI的校正过程。研究结果不仅能为实现森林叶面积指数和冠层功能高精度估算奠定理论基础，还能为应用激光雷达技术通过三维绿量大面积反演森林叶面积提供转换参数，为冠层分析系统测量叶面积指数提供校正系数，具有重要的科学意义和广阔的应用前景。