Response of plant communities to elevated CO_2

植物群落对 CO_2 升高的反应

基本信息

批准号：
07044176
负责人：
HIROSE Tadaki
金额：
$ 1.6万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1995
资助国家：
日本
起止时间：
1995 至无数据
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07044176/
关键词：
Abutilon theophrashi Ambrosia artemisiifolia Canopy photosynthesis CO_2 elevation Leaf area index Nitrogen use efficiency Plant community Stand structure

项目摘要

Elevated CO_2 may increase dry mass production of canopies directly through increasing net assimilation rate of leaves and also indirectly through increasing leaf area index (LAI). We studied the effects of CO_2 elevation on canopy productivity and development in mono-specific and mixed(1 : 1) stands of two co-occurring C_3 annual species, Abutilon theophrasti and Ambrosia artemisiifolia. The stands were established in the glasshouse with two CO_2 levels (360 and 700ml/l)under natural light conditions. The planting density was 100 per m2 and LAI increased up to 2.6 in 53-day growth. Root competition was excluded growing each plant in an individual pot. However, interference was apparent in the amount of photons absorbed by the plants and in photon absorption per unit leaf area. Greater photon absorption by Abutilon in the mixed stand was due to different canopy structures : Abutilon distributed leaves in the upper layrs in the canopy while Ambrosia distributed leaves more to the lower layrs. CO_2 elevation did not affect the relative performance and light interception of the two species in mixed stands. Total aboveground dry mass was significantly increased with CO_2 elevation, while no significant effects on leaf area development were observed. CO_2 elevation increased dry mass production by 30-50%, which was mediated by 35-38% increase in the net assimilation rate (NAR) and 37-60% increase in the nitrogen use efficiency (NUE,=net assimilation rate per unit leaf nitrogen). Since there was a strong overall correlation between LAI and aboveground nitrogen and no significant difference was found in the regression of LAI against aboveground nitrogen between the two CO_2 levels, we hypothesized that leaf area development was controlled by the amount of nitrogen taken up from the soil. This hypothesis suggests that the increased LAI with CO_2 elevation observed by several authors might be due to increased uptake of nitrogen with increased root growth.

升高的CO_2可以通过增加叶子的净同化速率以及通过增加叶面积指数（LAI）而直接增加冠层干燥的批量生产。我们研究了CO_2升高对单个单一特异性和混合（1：1）冠层生产率和发育的影响（1：1），这些林分是两个共发生的C_3年度种类，即Abutilon theophrasti和Ambrosia artemisiifolia。在自然光条件下，在温室中建立了两个CO_2级别（360和700ml/L）的车位。每平方英尺的种植密度为100，在53天生长中，LAI增加到2.6。根竞争被排除在单个锅中的每种植物。然而，干扰在植物吸收的光子量和每单位叶面积吸收的光子吸收中显而易见。混合支架中Abutilon吸收的光子吸收较大是由于不同的冠层结构：冠层上层中的abutilon分布的叶子，而Ambrosia分布的叶片则更多地分布在下层。 CO_2高程不会影响混合林分中两个物种的相对性能和光截距。与CO_2升高有关，地面干质量显着增加，而对叶片面积发育没有显着影响。 CO_2海拔高度产量增加了30-50％，这是由净同化速率（NAR）增加35-38％的介导的，氮的使用效率增加了37-60％（NUE，NUE，=每单位叶氮的净同化速率）。由于LAI和地上氮之间存在很强的总体相关性，因此在LAI的回归中与地面氮之间没有显着差异，因此我们假设叶片面积的发育受到从土壤中占据的氮气的控制。该假设表明，几位作者观察到的co_2升高的LAI增加可能是由于氮的摄取增加而导致根生长增加。