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Radial growth and cell wall structure of trees grown under elevated carbon dioxide concentrations

在高二氧化碳浓度下生长的树木的径向生长和细胞壁结构

基本信息

批准号：
11460076
负责人：
FUNADA Ryo
金额：
$ 9.22万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

We estimated long-term effects of elevated carbon dioxide concentrations [CO_2] on physiological and anatomical characteristics of trees, namely the stem growth, wood structure and characteristics of photosynthesis. Seedlings of larch (Larix sibirica and Larix kaempferi) and white birch (Betula platyphylla var. japonica) trees were grown in growth chambers under two [CO_2], ambient (360 ppm) and elevated (720 ppm), and with high or low levels of nutrients for one-three growing seasons. Elevated [CO_2] had no significant effects on stem height and stem diameter. However, the stem height and stem diameter were enhanced by the high level of nutrients and these increases were stimulated by elevated [CO_2]. Annual ring widths, cell numbers and cell diameters tended to increase, whereas cell wall thickness tended to decrease slightly in response to elevated [CO_2] , By contrast, there were no statistically significant differences in the relative area of cell wall, which was closely related to specific gravity of wood, indicating that elevated [CO_2] had few effects of changes in wood quality. In conclusion, there is no obvious enhancement in the capacity of carbon fixation by elevated [CO_2]. However, changes in the temporal pattern of stem growth and in anatomical features of the stem would occur under elevated [CO_2]. Although net assimilation rate under which seedlings grew was higher in elevated [CO_2] than in ambient [CO_2], little enhancement of photosynthesis rate of whole crown under elevated [CO_2] was observed because of the smaller specific leaf area and the acclimation of photosynthetic characteristics of leaves to [CO_2] which seedling grew. Such acclimation of photosynthesis was closely related to the decrease in amounts of soluble proteins and Rubisco, which is a key enzyme of photosynthesis, in leaves.

本文研究了CO_2浓度升高对树木生理解剖特性的长期影响，即对树干生长、木材结构和光合特性的影响。以西伯利亚落叶松（Larix sibirica）、日本落叶松（Larix kaempferi）和白色白桦（Betula platyphylla var.在大气CO_2浓度（360 ppm）和高浓度（720 ppm）两种CO_2浓度下，以及高、低营养水平下，分别进行1 ~ 3个生长季的生长试验。CO_2浓度升高对茎高和茎粗的影响不显著。但高营养水平促进了茎高和茎粗的生长，且这些生长受[CO_2]浓度升高的刺激。随着[CO_2]浓度的升高，年轮宽度、细胞数量和细胞直径呈增加趋势，细胞壁厚度呈轻微下降趋势，而与木材比重密切相关的细胞壁相对面积差异不显著，说明[CO_2]浓度升高对木材品质的影响不大。总之，[CO_2]浓度升高对固碳能力没有明显的增强作用。然而，在[CO_2]升高的情况下，茎生长的时间模式和茎的解剖特征会发生变化。高[CO_2]条件下，虽然幼苗生长的净同化率高于正常[CO_2]条件下，但由于幼苗比叶面积较小，叶片光合特性对[CO_2]的适应性较强，因此高[CO_2]条件下对全冠光合速率的提高作用不大。光合作用的这种驯化与叶片中可溶性蛋白质和光合作用关键酶Rubisco含量的下降密切相关。