Leaf canopy as a dynamic system: Ecophysiology and optimality in leaf turnover
Leaf canopy as a dynamic system: Ecophysiology and optimality in leaf turnover
复制标题
DOI：
10.1093/aob/mci050
复制
发表时间：
2005-02-01
期刊：
影响因子：
4.2
通讯作者：
Hikosaka, K
中科院分区：
文献类型：
--
作者：
Hikosaka, K
背景与目的在叶冠中，有树叶的翻转；也就是说，它们产生，衰老和下降。这些过程决定了冠层的叶面积，进而决定了冠层的光合作用。叶片周转率受环境因子的影响，且不同物种间存在差异。这篇综述讨论了植物冠层叶片动态的影响因素，重点是氮的作用。叶片的生产是由冠层光合作用支持的，而冠层光合作用是由光和叶片氮的分布决定的。叶片的氮决定光合能力。从根部吸收的氮分配给新叶。当叶片老化或光效降低时，部分叶片氮被吸收。被吸收的氮在新的器官中被重新利用，其余的随枯叶一起流失。汇源平衡在叶片衰老的调控中起着重要作用。已经提出了几个模型来预测对环境变化的反应。一个将氮用于光合作用的数学模型很好地解释了物种内部和物种之间叶片寿命的差异。结论当叶片更替处于稳定状态时，生物量产出与氮吸收之比等于凋落物与氮损失之比，与枯叶中氮浓度成反比。因此，枯叶中的氮浓度（氮吸收能力）和土壤中的氮有效性决定了冠层光合作用的速率。调节叶片的动态，使植物的碳增益和资源利用效率最大化。(C) 2004年植物学年鉴。
Background and Aims In a leaf canopy, there is a turnover of leaves; i.e. they are produced, senesce and fall. These processes determine the amount of leaf area in the canopy, which in turn determines canopy photosynthesis. The turnover rate of leaves is affected by environmental factors and is different among species. This mini-review discusses factors responsible for leaf dynamics in plant canopies, focusing on the role of nitrogen.Scope Leaf production is supported by canopy photosynthesis that is determined by distribution of light and leaf nitrogen. Leaf nitrogen determines photosynthetic capacity. Nitrogen taken up from roots is allocated to new leaves. When leaves age or their light availability is lowered, part of the leaf nitrogen is resorbed. Resorbed nitrogen is re-utilized in new organs and the rest is lost with dead leaves. The sink-source balance is important in the regulation of leaf senescence. Several models have been proposed to predict response to environmental changes. A mathematical model that incorporated nitrogen use for photosynthesis explained well the variations in leaf lifespan within and between species.Conclusion When leaf turnover is at a steady state, the ratio of biomass production to nitrogen uptake is equal to the ratio of litter fall to nitrogen loss, which is an inverse of the nitrogen concentration in dead leaves. Thus nitrogen concentration in dead leaves (nitrogen resorption proficiency) and nitrogen availability in the soil determine the rate of photosynthesis in the canopy. Dynamics of leaves are regulated so as to maximize carbon gain and resource-use efficiency of the plant. (C) 2004 Annals of Botany Company.