BACKGROUND AND AIMS The success of invasive plants can be attributed to many traits including the ability to adapt to variable environmental conditions. Whether by adaptation, acclimation or phenotypic plasticity, these plants often increase their resource-use efficiency and consequently, their fitness. The goal of this study was to examine the hydraulic and eco-physiological attributes of sun and shade populations of Pteridium aquilinum, a weedy fern, to determine whether the presence of vessels and other hydraulic attributes factors into its success under a variety of light conditions. METHODS Hydraulic traits such as cavitation resistance, hydraulic conductivity, photosynthesis, and water potential at turgor loss point were measured on fronds from sun and shade populations. Anatomical and structural traits such as conduit diameter and length, stomatal density and vein density were also recorded. Diurnal measures of leaf water potential and stomatal conductance complement these data. KEY RESULTS Gas-exchange was nearly double in the sun plants, as was water-use efficiency, leaf-specific conductivity, and stomatal and vein density. This was largely achieved by a decrease in leaf area, coupled with higher xylem content. There was no significant difference in petiole cavitation resistance between the sun and shade leaves, nor in xylem-specific conductivity. Hydraulic conduit diameters were nearly equivalent in the two leaf types. CONCLUSIONS Shifts in leaf area and xylem content allow P. aquilinum to occupy habitats with full sun, and adjust its physiology accordingly. High rates of photosynthesis explain in part the success of this fern in disturbed habitats, however, no change was observed in intrinsic xylem qualities such as cavitation resistance or conduit length. This suggests that P. aquilinum is constrained by its fundamental body plan, in contrast to seed plants, which show greater capacity for hydraulic adjustment.

中文翻译：

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有限的液压调节驱动 Pteridium aquilinum 对可变光的适应反应

背景和目的入侵植物的成功可归因于许多特性，包括适应可变环境条件的能力。无论是通过适应、驯化还是表型可塑性，这些植物通常都会提高它们的资源利用效率，从而提高它们的适应性。本研究的目的是检查 Pteridium aquilinum（一种杂草蕨类植物）的日光和阴凉种群的水力和生态生理特性，以确定在各种光照条件下是否存在血管和其他水力特性是其成功的因素。方法对日照和遮荫种群的叶状体进行抗空化、导水率、光合作用和膨压损失点水势等水力特性测定。解剖和结构特征，例如导管直径和长度，还记录了气孔密度和静脉密度。叶水势和气孔导度的昼夜测量补充了这些数据。主要结果 太阳植物中的气体交换几乎翻了一番，水分利用效率、叶片特定电导率以及气孔和脉密度也是如此。这主要是通过叶面积的减少以及较高的木质部含量来实现的。太阳叶和遮荫叶之间的叶柄空化阻力没有显着差异，木质部特定的电导率也没有显着差异。两种叶片类型的液压导管直径几乎相等。结论 叶面积和木质部含量的变化允许 P. aquilinum 占据充足阳光的栖息地，并相应地调整其生理机能。光合作用的高速率部分解释了这种蕨类植物在受干扰的栖息地中的成功，然而，没有观察到内在木质部质量如空化阻力或导管长度的变化。这表明 P. aquilinum 受其基本身体计划的限制，与种子植物相反，后者显示出更大的水力调节能力。