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

本项目的目的是通过制定估算方法，重建几十年来树木种群的结构和功能数量。发展针叶树种的同龄林分特别有意义。改造项目包括林分密度、林木生物量、个体生长量及其大小分布。并对变量的年际变化进行了估算。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的变量。这项研究的目的之一是证明这种重建是可能的。我们还试图通过研究重建的森林结构和功能的变化来评估全球变暖对森林生态系统的影响。我们表明，通过假设Hozumi，Shinozaki&Tadaki(1968)-3/2幂分布作为偶龄林分个体的生物量分布函数，并利用林分中约15棵最大树的胸高年轮数据，可以估计过去单株树木的大小分布函数的参数。即使对于已经从森林中消失的个体的大小和频率，重建也可以进行。此外，还提出了一种利用过去某一时期的“树干细长指数”参数值估算林分密度、林木各部位生物量、林分总材积、单株生长量及其大小分布的方法。这个参数是根据几棵树的树干分析数据计算出来的。在未来的研究中，有必要通过对过去有结构数据的林分重建的种群结构进行分析，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.