Conifers face increased drought mortality risks because of drought-induced embolism in their vascular system. Variation in embolism resistance may result from species differences in pit structure and function, as pits control the air seeding between water-transporting conduits. This study quantifies variation in embolism resistance and hydraulic conductivity for 28 conifer species grown in a 50-year-old common garden experiment and assesses the underlying mechanisms. Conifer species with a small pit aperture, high pit aperture resistance, and large valve effect were more resistant to embolism, as they all may reduce air seeding. Surprisingly, hydraulic conductivity was only negatively correlated with tracheid cell wall thickness. Embolism resistance and its underlying pit traits related to pit size and sealing were more strongly phylogenetically controlled than hydraulic conductivity and anatomical tracheid traits. Conifers differed in hydraulic safety and hydraulic efficiency, but there was no trade-off between safety and efficiency because they are driven by different xylem anatomical traits that are under different phylogenetic control.

中文翻译：

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坑和管胞解剖学解释了 28 种针叶树的水力安全性，但不能解释水力效率


由于干旱引起的血管系统栓塞，针叶树面临着更大的干旱死亡风险。抗栓塞能力的变化可能是由于物种坑结构和功能的差异造成的，因为坑控制输水管道之间的空气播种。这项研究量化了 50 年历史的普通花园实验中种植的 28 种针叶树品种的抗栓塞性和导水率的变化，并评估了其潜在机制。具有小孔孔径、高孔孔径阻力和大阀门效应的针叶树品种更能抵抗栓塞，因为它们都可能减少空气播种。令人惊讶的是，水力传导率仅与管胞细胞壁厚度呈负相关。与导水率和解剖管胞特征相比，抗栓塞性及其与凹坑大小和密封相关的潜在凹坑特征受到更强烈的系统发育控制。针叶树在水力安全性和水力效率方面存在差异，但安全性和效率之间没有权衡，因为它们是由处于不同系统发育控制下的不同木质部解剖特征驱动的。