Trade-offs between water transport capacity and drought resistance in neotropical canopy liana and tree species
Trade-offs between water transport capacity and drought resistance in neotropical canopy liana and tree species
复制标题
DOI：
10.1093/treephys/tpw086
复制
发表时间：
2017-10-01
期刊：
影响因子：
4
通讯作者：
Alvarez-Cansino, Leonor
中科院分区：
文献类型：
--
作者：
De Guzman, Mark E.;Santiago, Louis S.;Alvarez-Cansino, Leonor
在热带森林冠层，这是至关重要的上部枝条有效地提供水分的叶片生理功能，同时安全地防止损失的导水率由于土壤水分亏缺或高蒸发需求期间的空化。我们比较了在季节性干燥的热带森林上层树冠树木和藤本植物的水力生理，以测试是否权衡水运输的安全性和效率之间的形状这两个主要的热带木本生长形式之间的水力功能的差异。我们发现，藤本植物比树木表现出更大的最大茎特定导水率，但在负水势比树木小的情况下失去导水率，导致水分运输的安全性和效率之间呈负相关和权衡。藤本植物叶水势的日变化也比乔木大。水势日变化幅度与边材电容呈负相关，表明藤本植物高度依赖传导能力来维持叶片水分状况，而树木则更多地依赖茎中的贮水来维持叶片水分状况。叶氮浓度相关的最大叶片比水力传导度只有藤本植物，这表明更大的水运输能力是更多的联系在藤本植物的叶过程相比，树木。我们的研究结果是一致的水运输的安全性和效率之间的权衡，并可能对新热带森林中藤本植物丰富度的增加产生影响。
In tropical forest canopies, it is critical for upper shoots to efficiently provide water to leaves for physiological function while safely preventing loss of hydraulic conductivity due to cavitation during periods of soil water deficit or high evaporative demand. We compared hydraulic physiology of upper canopy trees and lianas in a seasonally dry tropical forest to test whether trade-offs between safety and efficiency of water transport shape differences in hydraulic function between these two major tropical woody growth forms. We found that lianas showed greater maximum stem-specific hydraulic conductivity than trees, but lost hydraulic conductivity at less negative water potentials than trees, resulting in a negative correlation and trade-off between safety and efficiency of water transport. Lianas also exhibited greater diurnal changes in leaf water potential than trees. The magnitude of diurnal water potential change was negatively correlated with sapwood capacitance, indicating that lianas are highly reliant on conducting capability to maintain leaf water status, whereas trees relied more on stored water in stems to maintain leaf water status. Leaf nitrogen concentration was related to maximum leaf-specific hydraulic conductivity only for lianas suggesting that greater water transport capacity is more tied to leaf processes in lianas compared to trees. Our results are consistent with a trade-off between safety and efficiency of water transport and may have implications for increasing liana abundance in neotropical forests.