Wide Range Measurement of Surface Vegetation as Global Environment Asset and Development of Its Function Evaluation System

开发了基于航空激光测高植被剖面估算大面积森林生物量和叶面积指数（LAI）的全新方法，并建立了基于激光GIS的森林清查系统，以适应这些面向环境的信息以及现有的面向木材的信息和数据。构成研究基础的植被剖面数据是在本项目中通过对Ontakesan山的飞行以及从爱媛大学实验森林和加拿大北方森林600公里长的样带的其他来源获得的。同时进行了一系列的森林清查，以获得现有森林生物量和LAI的地面真实值。基于这些遥感和地面数据，开发了三种不同的从植被剖面中推断森林生物量和LAI的方法。第一种方法是基于剖面的傅立叶分析，它产生功率谱，进而给出平均冠层直径作为功率最大值对应的波长。其他重要的林分特征，如平均胸径、树高和树梢密度，然后由平均冠层直径导出，最终得到林分蓄积量和生物量的估计。第二种方法基于分子动力学中平均自由程的概念，并给出叶片密度作为叶片平均激光穿透深度的函数的估计，该函数与单叶的平均面积一起，可以估计冠层的整个叶片面积，从而估算LAI。最后一种方法将植被剖面与林分蓄积量的积分联系起来，用平均树高与干密度的乘积很好地表示了这一点。

Entirely new methods of estimating forest biomass and leaf area index (LAI) over an extensive area from vegetation profile obtained by airborne laser altimetry were developed, and a laser-based GIS forest inventory system was established to accommodate such environment-oriented information along with the existing timber-oriented information and data.The vegetation profile data, which constitutes the basis of the research, was obtained by a flight over the Mt. Ontakesan in the present project, as well as from other sources for the Experimental Forest of Ehime University and for a 600km long transect over the boreal forest of Canada. Also a series of forest inventory surveys was conducted to obtain ground truth for existing forest biomass and LAI. Based on these remotely sensed and ground data, three different methods of deducing forest biomass and LAI from the vegetation profile were developed. The first method is based on the Fourier analysis of the profile, which yields power spectrum, which further in turn gives the mean canopy diameter as the wavelength corresponding to the power maxima. Other important stand characteristics such as mean DBH, tree height and stern density are then derived from the mean canopy diameter, eventually leading to estimates of stand stocking and biomass. The second method is based on the notion of the mean free path in molecular kinetics and gives an estimate of leaf density as a function of the mean laser penetration depth into the foliage, which along with the mean area of a single leaf, results in an estimate of entire leaf area of the canopy anti thus the LAI. The last method correlates the integration of the vegetation profile with stand stocking, which is well represented by the product of mean tree height and stem density.