Phenotypic plasticity and developmental instability in leaf traits are common in oak species but the role of environmental factors is not well understood. To decipher possible correlations between different leaf traits and effects of the position of leaves within the tree canopy, we quantified the plasticity of three leaf traits of 30 trees of Quercus alba L., Quercus palustris Muench and Quercus velutina Lam. We hypothesized that trees could modify the shape of their leaves for better adaptation to the variable microclimate within the canopy. Our results demonstrated that the south and north outer leaves were significantly smaller, more lobed and denser than those situated in the inner canopy. The order of leaves on the branch accounted for the plasticity of leaf traits in Q. alba only. Plasticity of lobing in Q. alba and Q. velutina depended on the height of the trees. We detected fluctuating asymmetry (FA) in all three species, but the source of variation depended on branch position in Q. velutina only. FA was more pronounced in north‐facing leaves. Plasticity of the leaf traits ranged from small to medium. Plasticity of leaf area and leaf mass per area (LMA) depended on the branch position. However, the plasticity of lobation was not affected by the location of a branch within the tree canopy. Quercus alba and Q. palustris had similar plastic responses but the plasticity of Q. velutina was significantly smaller. We concluded that individual plants detect and cope with environmental stress through vegetative organ modification.

中文翻译：

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三种栎属植物的叶片形态：暴露的叶子越多，叶片越小，越裂，越密

叶性状的表型可塑性和发育不稳定性在橡树种中很常见，但环境因素的作用尚不清楚。为了破译不同叶子性状之间可能的相关性以及树冠内叶子位置的影响，我们量化了 30 棵 Quercus alba L.、Quercus palustris Muench 和 Quercus velutina Lam 的三种叶子性状的可塑性。我们假设树木可以改变叶子的形状，以更好地适应树冠内多变的小气候。我们的结果表明，与位于内冠层的叶子相比，南、北外叶明显更小、更裂、更密。枝条上的叶子顺序仅解释了Q. alba叶子性状的可塑性。Q. alba 和 Q. 中裂片的可塑性 velutina 取决于树的高度。我们在所有三个物种中都检测到波动的不对称性 (FA)，但变异的来源仅取决于 Q. velutina 的分支位置。FA 在朝北的叶子中更为明显。叶片性状的可塑性从小到中等。叶面积和单位面积叶质量 (LMA) 的可塑性取决于分支位置。然而，裂片的可塑性不受树冠内树枝位置的影响。Quercus alba 和 Q. palustris 具有相似的塑性响应，但 Q. velutina 的可塑性明显较小。我们得出的结论是，单个植物通过营养器官修饰来检测和应对环境压力。但变异的来源仅取决于 Q. velutina 的分支位置。FA 在朝北的叶子中更为明显。叶片性状的可塑性从小到中等。叶面积和单位面积叶质量 (LMA) 的可塑性取决于分支位置。然而，裂片的可塑性不受树冠内树枝位置的影响。Quercus alba 和 Q. palustris 具有相似的塑性响应，但 Q. velutina 的可塑性明显较小。我们得出的结论是，单个植物通过营养器官修饰来检测和应对环境压力。但变异的来源仅取决于 Q. velutina 的分支位置。FA 在朝北的叶子中更为明显。叶片性状的可塑性从小到中等。叶面积和单位面积叶质量 (LMA) 的可塑性取决于分支位置。然而，裂片的可塑性不受树冠内树枝位置的影响。Quercus alba 和 Q. palustris 具有相似的塑性响应，但 Q. velutina 的可塑性明显较小。我们得出的结论是，单个植物通过营养器官修饰来检测和应对环境压力。裂片的可塑性不受树冠内树枝位置的影响。Quercus alba 和 Q. palustris 具有相似的塑性响应，但 Q. velutina 的可塑性明显较小。我们得出结论，单个植物通过营养器官修饰来检测和应对环境压力。裂片的可塑性不受树冠内树枝位置的影响。Quercus alba 和 Q. palustris 具有相似的塑性响应，但 Q. velutina 的可塑性明显较小。我们得出结论，单个植物通过营养器官修饰来检测和应对环境压力。