The performance and distribution of woody species strongly depend on their adjustment to environmental conditions based on genotypic and phenotypic properties. Since more intense and frequent drought events are expected due to climate change, xylem hydraulic traits will play a key role under future conditions, and thus knowledge of hydraulic variability is of key importance. In this study, we aimed to investigate the variability in hydraulic safety and efficiency of the conifer shrub Juniperus communis based on analyses along an elevational transect and a common garden approach. We studied (i) juniper plants growing between 700 and 2000 m a.s.l. Innsbruck, Austria, and (ii) plants grown in the Innsbruck botanical garden (Austria) from seeds collected at different sites across Europe (France, Austria, Ireland, Germany and Sweden). Due to contrasting environmental conditions at different elevation and provenance sites and the wide geographical study area, pronounced variation in xylem hydraulics was expected. Vulnerability to drought-induced embolisms (hydraulic safety) was assessed via Cavitron and ultrasonic acoustic emission technique, and the specific hydraulic conductivity (hydraulic efficiency) via flow measurements. Contrary to our hypothesis, relevant variability in hydraulic safety and efficiency was neither observed across elevations, indicating a low phenotypic variation, nor between provenances, despite expected genotypic differences. Interestingly, the provenance from the most humid and warmest site (Ireland) and the northernmost provenance (Sweden) showed the highest and the lowest embolism resistance, respectively. The hydraulic conductivity was correlated with plant height, which indicates that observed variation in hydraulic traits was mainly related to morphological differences between plants. We encourage future studies to underly anatomical traits and the role of hydraulics for the broad ecological amplitude of J. communis.

中文翻译：

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杜松种群在水力安全性和效率方面表现出较低的变异性。

木本物种的性能和分布很大程度上取决于它们对基于基因型和表型特性的环境条件的调整。由于气候变化预计会出现更加严重和频繁的干旱事件，木质部水力特征将在未来条件下发挥关键作用，因此了解水力变异性至关重要。在这项研究中，我们的目的是基于沿高程样带和常见花园方法的分析，研究针叶树灌木杜松的水力安全性和效率的变异性。我们研究了 (i) 奥地利因斯布鲁克海拔 700 至 2000 米之间生长的杜松植物，以及 (ii) 因斯布鲁克植物园（奥地利）中生长的植物，其种子是在欧洲不同地点（法国、奥地利、爱尔兰、德国和瑞典）收集的）。由于不同海拔和产地的环境条件对比以及广泛的地理研究区域，预计木质部水力学存在显着变化。通过Cavitron 和超声波声发射技术评估对干旱引起的栓塞的脆弱性（水力安全性） ，并通过流量测量评估特定水力传导率（水力效率）。与我们的假设相反，尽管存在预期的基因型差异，但在不同海拔地区都没有观察到水力安全和效率的相关变异，表明表型变异较低，也没有在不同来源之间观察到水力安全和效率的相关变异。有趣的是，来自最潮湿和最温暖地区（爱尔兰）和最北端（瑞典）的来源分别表现出最高和最低的栓塞抵抗力。导水率与株高相关，这表明观察到的水力性状变化主要与植物之间的形态差异有关。我们鼓励未来研究潜在的解剖学特征和水力学对于大叶黄蜂广泛生态范围的作用。