Plant Ecophysiology and Evolution Group, State Key Laboratory for Conservation and Utilisation of Subtropical Agro-Bioresources, Guangxi University, Nanning, Guangxi 530004, China.
Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi 530004, China.
Tree Physiol. 2023 Feb 4;43(2):234-247. doi: 10.1093/treephys/tpac119.
The hydraulic traits of a plant species may reflect its climate adaptations. Southwest China is considered as a biodiversity hotpot of the genus Quercus (oak). However, the hydraulic adaptations of Asian oaks to their climate niches remain unclear. Ten common garden-grown oak species with distinct natural distributions in eastern Asia were used to determine their stem xylem embolism resistance (water potential at 50% loss of hydraulic conductivity, P50), stem hydraulic efficiency (vessel anatomy and sapwood specific hydraulic conductivity (Ks)) and leaf anatomical traits. We also compiled four key functional traits: wood density, hydraulic-weighted vessel diameter, Ks and P50 data for 31 oak species from previous literature. We analyzed the relationship between hydraulic traits and climatic factors over the native ranges of 41 oak species. Our results revealed that the 10 Asian oak species, which are mainly distributed in humid subtropical habitats, possessed a stem xylem with low embolism resistance and moderate hydraulic efficiency. The deciduous and evergreen species of the 10 Asian oaks differed in the stem and leaf traits related to hydraulic efficiency. Ks differed significantly between the two phenological groups (deciduous and evergreens) in the 41-oak dataset. No significant difference in P50 between the two groups was found for the 10 Asian oaks or the 41-oak dataset. The oak species that can distribute in arid habitats possessed a stem xylem with high embolism resistance. Ks negatively related to the humidity of the native range of the 10 Asian oaks, but showed no trend when assessing the entire global oak dataset. Our study suggests that stem hydraulic conductivity and embolism resistance in Quercus species are shaped by their climate niche. Our findings assist predictions of oak drought resistance with future climate changes for oak forest management.
植物的水力特性可能反映了其对气候的适应。中国西南部被认为是栎属（橡树）生物多样性的热点地区。然而，亚洲栎属植物对其气候小生境的水力适应仍不清楚。本研究使用了 10 种在东亚具有不同自然分布的常见的栽培栎属树种，以确定它们的茎木质部栓塞抗性（水力传导率损失 50%时的水势，P50）、茎水力效率（导管解剖结构和边材比导水率（Ks））和叶片解剖结构特征。我们还编译了 4 个关键功能性状：木材密度、水力加权导管直径、Ks 和 P50 的数据，这些数据来自之前文献中 31 种栎属植物。我们分析了 41 种栎属植物的自然分布范围内，水力性状与气候因子之间的关系。结果表明，这 10 种主要分布在潮湿亚热带生境中的亚洲栎属树种，其茎木质部栓塞抗性较低，水力效率中等。这 10 种亚洲栎属树种的落叶树种和常绿树种在与水力效率相关的茎和叶特征上存在差异。在 41 种栎属植物数据集上，Ks 在两个物候组（落叶和常绿）之间存在显著差异。在 10 种亚洲栎属植物或 41 种栎属植物数据集上，未发现 P50 在两组之间存在显著差异。可以分布在干旱生境中的栎属树种具有较高的栓塞抗性。Ks 与 10 种亚洲栎属植物的自然分布范围的湿度呈负相关，但在评估整个全球栎属植物数据集时没有趋势。本研究表明，栎属植物的茎水力传导率和栓塞抗性是由其气候小生境决定的。我们的研究结果有助于预测栎属植物对未来气候变化的耐旱性，以便对栎属森林进行管理。
