Civil and Environmental Engineering, University of California, Berkeley, Berkeley, California, USA.
Civil, Environmental, and Geo- Engineering, University of Minnesota, Minneapolis, Minnesota, USA.
Plant Cell Environ. 2023 Sep;46(9):2726-2746. doi: 10.1111/pce.14649. Epub 2023 Jun 20.
Observations show vulnerability segmentation between stems and leaves is highly variable within and between environments. While a number of species exhibit conventional vulnerability segmentation (stem leaf ), others exhibit no vulnerability segmentation and others reverse vulnerability segmentation (stem leaf ). We developed a hydraulic model to test hypotheses about vulnerability segmentation and how it interacts with other traits to impact plant conductance. We do this using a series of experiments across a broad parameter space and with a case study of two species with contrasting vulnerability segmentation patterns: Quercus douglasii and Populus trichocarpa. We found that while conventional vulnerability segmentation helps to preserve conductance in stem tissues, reverse vulnerability segmentation can better maintain conductance across the combined stem-leaf hydraulic pathway, particularly when plants have more vulnerable s and have hydraulic segmentation with greater resistance in the leaves. These findings show that the impacts of vulnerability segmentation are dependent upon other plant traits, notably hydraulic segmentation, a finding that could assist in the interpretation of variable observations of vulnerability segmentation. Further study is needed to examine how vulnerability segmentation impacts transpiration rates and recovery from water stress.
观测表明，茎和叶之间的脆弱性分段在内部和环境之间具有高度可变性。虽然许多物种表现出常规的脆弱性分段（茎-叶），但其他物种则没有脆弱性分段，还有一些物种表现出相反的脆弱性分段（茎-叶）。我们开发了一个水力模型来测试关于脆弱性分段的假设，以及它如何与其他特征相互作用来影响植物导水率。我们通过一系列跨越广泛参数空间的实验以及对两种具有不同脆弱性分段模式的物种（Douglas 栎和绒毛杨）的案例研究来实现这一目标。我们发现，虽然常规的脆弱性分段有助于保持茎组织中的导水率，但相反的脆弱性分段可以更好地维持整个茎-叶水力途径的导水率，特别是当植物的叶片具有更高的脆弱性和更大的水力分段阻力时。这些发现表明，脆弱性分段的影响取决于其他植物特征，特别是水力分段，这一发现可以帮助解释脆弱性分段的可变观测结果。需要进一步研究来检验脆弱性分段如何影响蒸腾速率和从水分胁迫中的恢复。
