Leaf Photosynthetic Capacity of Sunlit and Shaded Mature Leaves in a Deciduous Forest
Leaf Photosynthetic Capacity of Sunlit and Shaded Mature Leaves in a Deciduous Forest
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DOI：
10.3390/f11030318
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发表时间：
2020-03-01
期刊：
影响因子：
2.9
通讯作者：
Jin, Jia
中科院分区：
文献类型：
--
作者：
Song, Guangman;Wang, Quan;Jin, Jia
清楚地了解光合能力的动态对于生态系统碳吸收的准确建模至关重要。然而，这样的动态信息很难获得，并且极大地阻碍了我们对碳循环的理解。尽管在将光合能力的动态信息耦合到模型中已经付出了巨大的努力，但使用源于光合能力和其他可用叶片参数之间的密切关系的“代理”仍然是流行的选择。不幸的是，尚未就此类“代理”达成共识，导致它们仅适用于有限的情况。在本研究中，我们的目的是确定低温落叶林中成熟阔叶的光合能力（以最大羧化率 V-cmax 表示）与叶片性状之间是否存在密切关系。这是基于长期原位数据集，包括 2014 年至 2019 年叶片成熟期阳光照射和遮荫叶片的叶片叶绿素含量 (Chl)、叶片氮浓度（N 面积、N 质量）、叶片碳浓度（C 面积、C 质量）、当量水厚度 (EWT)、单位面积叶片质量 (LMA) 以及从中得出 V-cmax 的叶片气体交换测量值。在此期间，阳光照射和遮荫叶片的V-cmax值相对稳定，并且没有发生统计上显着的年际变化(p > 0.05)。然而，这不适用于特定物种。路径分析显示，N 区域是阳光照射叶片 V-cmax 的主要贡献者 (0.502)，而 LMA 与阴影叶片 V-cmax 的直接关系最大 (0.625)。如果没有叶类型信息可用，则 LMA 已被进一步确认为主代理。这些发现为更好地了解光合作用并预测温带落叶林的碳和水循环提供了一种有前景的方法。
A clear understanding of the dynamics of photosynthetic capacity is crucial for accurate modeling of ecosystem carbon uptake. However, such dynamical information is hardly available and has dramatically impeded our understanding of carbon cycles. Although tremendous efforts have been made in coupling the dynamic information of photosynthetic capacity into models, using "proxies" rooted from the close relationships between photosynthetic capacity and other available leaf parameters remains the popular selection. Unfortunately, no consensus has yet been reached on such "proxies", leading them only applicable to limited cases. In this study, we aim to identify if there are close relationships between the photosynthetic capacity (represented by the maximum carboxylation rate, V-cmax) and leaf traits for mature broadleaves within a cold temperature deciduous forest. This is based on a long-term in situ dataset including leaf chlorophyll content (Chl), leaf nitrogen concentration (N-area, N-mass), leaf carbon concentration (C-area, C-mass), equivalent water thickness (EWT), leaf mass per area (LMA), and leaf gas exchange measurements from which V-cmax was derived, for both sunlit and shaded leaves during leaf mature periods from 2014 to 2019. The results show that the V-cmax values of sunlit and shaded leaves were relatively stable during these periods, and no statistically significant interannual variations occurred (p > 0.05). However, this is not applicable to specific species. Path analysis revealed that N-area was the major contributor to V-cmax for sunlit leaves (0.502), while LMA had the greatest direct relationship with V-cmax for shaded leaves (0.625). The LMA has further been confirmed as a primary proxy if no leaf type information is available. These findings provide a promising way to better understand photosynthesis and to predict carbon and water cycles in temperate deciduous forests.