Light acquisition and use by individuals competing in a dense stand of an annual herb, Xanthium canadense
Light acquisition and use by individuals competing in a dense stand of an annual herb, Xanthium canadense
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DOI：
10.1007/s004420050740
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发表时间：
1999-03-01
期刊：
影响因子：
2.7
通讯作者：
Hirose, T
中科院分区：
文献类型：
--
作者：
Hikosaka, K;Sudoh, S;Hirose, T
通过确定一年一度密集的单特异性立场中单个植物的生长和光合作用来评估个人在种内竞争中光的重要性和利用的重要性。木炭加拿大。使用冠层光合作用模型计算了看台中单个植物的光合作用，其中假定叶片光合作用是叶氮含量和光的可用性的功能。个体的估计光合速率与测得的生长速率密切相关。每单位地面质量的光合速率（RPR，相对光合速率）随着地上质量的增加而增加，表明看台中的不对称（单面）竞争。但是，较大的个体具有相似的RPR，表明对称（双面）竞争。这些结果与观察到整个林分的大小不平等的观察结果一致，但随着较大个体的增长而增加。一个人的RPR被计算为每单位的吸收光子通量的乘积（PHI（质量））和光使用效率（LUE，每单位吸收光子通量的光合作用）。 phi（质量）表明了光获取的效率，并且在较大的个体中较高，而在地上质量中间质量的个体中，LUE最高。 LUE取决于叶氮含量。在早期阶段，较小个体的叶氮含量与最大化的叶子相似。随着较小个体的增长，对较小个体的光的可用性降低，而氮含量并未明显变化，从而减少了他们的lue。我们认为，看台中的个体之间的不对称竞争主要是由于较小个体的光获取和轻度使用的效率降低。
The importance of light acquisition and utilization by individuals in intraspecific competition was evaluated by determining growth and photosynthesis of individual plants in a dense monospecific stand of an annual. Xanthium canadense. Photosynthesis of individual plants in the stand was calculated using a canopy photosynthesis model in which leaf photosynthesis was assumed to be function of leaf nitrogen content and light availability. The estimated photosynthetic rates of individuals were strongly correlated with the measured growth rates. Photosynthetic rates per unit aboveground mass (RPR, relative photosynthetic rate) increased with increasing aboveground mass, suggesting asymmetric (one-sided) competition in the stand. However, larger individuals had similar RPRs, suggesting symmetric (two-sided) competition. These results were consistent with the observation that size inequality over the whole stand increased with growth, but it remained stable among the larger individuals. The RPR of an individual was calculated as the product of absorbed photon flux per unit aboveground mass (Phi(mass)) and light use efficiency (LUE, photosynthesis per unit absorbed photon flux). Phi(mass) indicates the efficiency of light acquisition, and was higher in larger individuals in the stand, while LUE was highest in individuals with intermediate aboveground mass. LUE depends on leaf nitrogen content. At an early stage, leaf nitrogen contents of smaller individuals were similar to those that maximize LUE. Light availability to smaller individuals decreased as they grew, while their nitrogen contents did not change markedly, which decreased their LUE. We con eluded that asymmetric competition among individuals in the stand resulted mainly from lower efficiencies in both light acquisition and light use by smaller individuals.