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Plant ontogenetic changes in vein and stomatal traits and their relationship with economic traits in leaves of three Mediterranean oaks
Journal of Plant Ecology ( IF 2.7 ) Pub Date : 2021-05-22 , DOI: 10.1093/jpe/rtab051
Sonia Mediavilla 1 , Ignacio Martín 2 , Alfonso Escudero 1
Affiliation  

Abstract
Aims
We compared vein and stomatal traits of seedlings and adults of three Mediterranean Quercus species. Previous work suggests that gas-exchange rates tend to be higher at the seedling stage than in adults. Our objective was to determine whether vein and stomatal traits vary throughout whole-plant ontogeny in parallel with the changes in gas-exchange rates. We addressed the following alternative hypotheses: hypothesis 1—seedlings show higher vein and stomatal densities than adults; and hypothesis 2—seedlings have lower investments in vascular tissues to reduce construction costs.
Methods
Ten specimens from each growth stage were randomly sampled for each species in a location in central-western Spain. We measured mean stomatal and vein traits (size and number of stomata per unit of leaf area, vein density, vein volume, vein to epidermis distance), leaf mass per area and lamina thickness.
Important Findings
Minor vein density and vein volume per area increased with tree age, which seems inconsistent with the ontogenetic trends in gas-exchange rates. This discrepancy is in support of our hypothesis 2, and it suggests that, at the seedling stage, reducing investments in vascular tissues in benefit of maximizing growth rates is a priority. Larger interveinal distances in seedlings were compensated by smaller vein to epidermis distances. The thin leaves of the seedlings may thus constitute as a necessary trait for achieving shorter path length distances for the transport of water to evaporation sites without the need for a strong investment in costly vascular tissues.


中文翻译:

三种地中海橡树叶脉和气孔性状的植物个体发育变化及其与经济性状的关系

摘要
目标
我们比较了三种地中海栎属物种的幼苗和成虫的静脉和气孔特征。以前的工作表明,幼苗阶段的气体交换率往往高于成人。我们的目标是确定静脉和气孔特征是否在整个植物个体发育过程中与气体交换率的变化平行变化。我们提出了以下替代假设:假设 1——幼苗的静脉和气孔密度高于成虫;假设2——幼苗对维管组织的投资较低,以降低建设成本。
方法
在西班牙中西部的一个地点,为每个物种随机抽取了来自每个生长阶段的 10 个样本。我们测量了平均气孔和叶脉特征(每单位叶面积的气孔大小和数量、叶脉密度、叶脉体积、叶脉到表皮的距离)、每面积叶质量和叶片厚度。
重要发现
小静脉密度和单位面积的静脉体积随着树龄的增加而增加,这似乎与气体交换率的个体发育趋势不一致。这种差异支持我们的假设 2,它表明,在幼苗阶段,减少对维管组织的投资以最大化生长速率是一个优先事项。幼苗中较大的脉间距离通过较小的脉到表皮距离来补偿。因此,幼苗的薄叶可能构成实现将水输送到蒸发部位的更短路径长度距离的必要性状,而无需对昂贵的维管组织进行大量投资。
更新日期:2021-05-22
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