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Adjustment of leaf anatomical and hydraulic traits across vertical canopy profiles of young broadleaved forest stands
Trees ( IF 2.3 ) Pub Date : 2021-07-16 , DOI: 10.1007/s00468-021-02181-0
Arne Sellin 1 , Meeli Alber 1 , Katrin Rosenvald 1 , Anna Katarzyna Jasińska 2
Affiliation  

Key message

No evidence of coordination between leaf hydraulic function and stomatal characteristics was observed in young hybrid aspen stands attributable to the near-anisohydric behaviour and the fast-growing nature of this species.

Abstract

Within forest canopies, there are environmental gradients that enhance water losses in the direction of treetops. Therefore, the foliar morpho-anatomical plasticity, which allows plant acclimation to environmental variations, is of great importance, but empirical information about the relationship between leaf structural and functional traits is inconsistent, varying with ecological requirements and the life strategy of the species. In this study, leaf hydraulic conductance, anatomical structure, and stomatal morphology were investigated in young hybrid aspen (Populus tremula × P. tremuloides) stands to elucidate the coordination between structural and hydraulic traits within the canopy. Stomatal size and density demonstrated opposite trends with respect to leaf location, leading to a relatively uniform spatial distribution of potential gas exchange capacity in the canopy. The hydraulic system of branches was adjusted to maximise the potential water supply in the midcanopy, containing nearly half of the trees’ total photosynthetic surface. Most vascular traits in both the petioles and laminae demonstrated stronger development towards the treetop that should enhance the water supply of the upper foliage, which is exposed to higher irradiance and atmospheric evaporative demand. Small increases in the total vein density expressed per unit lamina area in the upper canopy could not compensate for substantial leaf thickening, resulting in decreased vein density expressed per unit lamina volume and increasing the resistance of the leaf extravascular pathway. No solid evidence of coordination was found between leaf hydraulic function and stomatal characteristics attributable to the near-anisohydric behaviour and the fast-growing nature of this species.



中文翻译:

阔叶林幼林垂直冠层剖面叶片解剖学和水力性状的调整

关键信息

在年轻的杂交白杨林中,没有观察到叶水力功能和气孔特征之间协调的证据,这归因于该物种的近等水行为和快速生长的性质。

抽象的

在森林冠层内,有环境梯度会增加树梢方向的水分流失。因此,允许植物适应环境变化的叶片形态解剖可塑性非常重要,但关于叶片结构和功能性状之间关系的经验信息不一致,随生态要求和物种的生活策略而变化。在这项研究中,研究了幼年杂交白杨(Populus tremula  ×  P. tremuloides)的叶片水力传导、解剖结构和气孔形态) 阐明冠层内结构和水力特征之间的协调。气孔大小和密度在叶片位置方面表现出相反的趋势,导致冠层中潜在气体交换能力的空间分布相对均匀。调整树枝的液压系统,以最大限度地提高中间树冠的潜在供水量,其中包含树木总光合表面的近一半。叶柄和叶片中的大多数维管性状都表现出向树梢的更强发育,这应该会增强上部叶子的供水,这些叶子暴露于更高的辐照度和大气蒸发需求。上部冠层中每单位叶片面积表达的总静脉密度的小幅增加不能补偿大量的叶片增厚,导致每单位叶片体积表达的静脉密度降低,并增加叶片血管外通路的阻力。由于该物种的近等水行为和快速生长的性质,在叶片水力功能和气孔特征之间没有发现协调的确凿证据。

更新日期:2021-07-16
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