Paleo-ecophysiology of forests : reconstructing structure and function of tree populations.

本项目的目的是通过发展这种估计方法来重建几十年来树木种群的结构和功能数量。针叶林的平均年龄的发展是特别感兴趣的。重建项目包括林分密度、各部分生物量、个体生长及其大小分布。并对各变量的年变化进行了估计。我们使用从实地观测中获得的硬数据进行重建。没有试图估计已经从现场消失的分解或死亡变量。这项研究的目的之一是证明这种重建是可能的。我们还打算通过研究森林结构和功能的重建变化来评估全球变暖对森林生态系统的影响。我们表明，过去可以通过假设Hozumi， Shinozaki和Tadaki（1968）的-3/2功率分布作为均匀年龄的林分个体的生物量分布函数，并使用林分中约15棵最大树木的胸高的树木年轮数据来估计单个树木的大小分布函数的参数。重建甚至可以对已经从森林中消失的个体的大小和频率进行重建。此外，还提出了一种利用过去给定时间的“茎长细度指数”参数值来估算林分密度、树木各部分生物量、林分总干积、单株生长量及其大小分布的方法。该参数是根据几棵树的树干分析数据计算得出的。在未来的研究中，有必要通过对结构数据已存在一段时间的林分的种群结构重建分析来评估本方法的准确性。

The purpose of the present project is to reconstruct structure and functional quantities of tree populations for over several decades by developing methods for such estimation. Development of even-aged stands of coniferous species is of particular interest. The items to be reconstructed include stand density, biomass of tree parts, growth of individuals and its size distribution. Yearly changes of the variables are also estimated. We used hard data taken from the field observations for reconstruction. No attempts had been made for estimation of variables that had already disappeared from the scene for decomposition or mortality. One of the aims of this research is to show that such reconstruction is possible. We also intend to use the method for assessing the effect of the global warming on forest ecosystems by examining the reconstructed changes in forest structure and function.We showed that it is possible to estimate parameters of the size distribution function of individual trees in the past by assuming Hozumi, Shinozaki & Tadaki's (1968) -3/2 power distribution as the biomass distribution function of individuals in even-aged stands, and by the use of tree ring data at breast height of about 15 largest trees in the stand. The reconstruction could be done even for the size and frequency of individuals that have already disappeared from the forest. In addition, a method was developed to estimate stand density, biomass of tree parts, total stem volume of the stand, growth of individual trees and their size distribution in the past, by applying the parameter value of the so called "stem slenderness index" for a given time in the past. This parameter is calculated from the stem analysis data of several trees. Assessment of accuracy of the present method is necessary in the future studies through the analysis of reconstructed population structure for stands of which structural data exist for a time in the past.