Key message

Canopy tree species with a large mean xylem vessel diameter has a high sensitivity of stomatal conductance to vapor pressure deficit in a wet tropical rainforest in Malaysia.

Abstract

We investigated the diurnal variation of stomatal conductance to water vapor (g_s) and leaf water relations in nine tropical rainforest canopy tree species in Malaysia to investigate the sensitivity of stomatal conductance to VPD and its dependence on leaf water relations. We focused on the effect of wood anatomical properties on the stomatal sensitivity to VPD. Negative correlations were obtained between leaf-to-air VPD (VPD_leaf) and g_s for all species, in which interspecific variation was obtained for the sensitivity of g_s to VPD_leaf with the range of VPD_leaf being 1.2–5.9 kPa. The species with large mean xylem vessel diameter had high sensitivity of g_s to VPD_leaf. Although significant variations were obtained among the species for leaf water relations, such as relative water content at the turgor loss point (RWC_tlp) and water potential at the turgor loss point (Ψ_tlp), these water relations were not related to the stomatal sensitivity to VPD_leaf. In the wet tropical forest in the present study, VPD_leaf was the main regulator of g_s in the nine tree species. The high sensitivity of g_s to VPD_leaf in the trees with a large vessel area may contribute to the maintenance of an adequate leaf water status, e.g., high levels of Ψ_leaf, throughout the day, across a period of varying air temperature.

中文翻译：

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马来西亚湿热带雨林中9种冠层树种气孔导度对水汽压亏缺的敏感性及其对叶片水分关系和木材解剖的依赖性

关键信息

在马来西亚的热带雨林中，木质部平均直径大的冠层树种对气孔导度对蒸气压亏缺具有很高的敏感性。

抽象

我们调查了马来西亚9种热带雨林冠层树种气孔导度对水汽（g _s）和叶片水关系的日变化，以研究气孔导度对VPD的敏感性及其对叶片水关系的依赖性。我们专注于木材解剖特性对气孔对VPD敏感性的影响。叶-空气VPD（VPD之间获得负相关_叶）和克_小号的所有物种，在将其用于的灵敏度得到种间变异克_小号到VPD_叶与VPD的范围_叶为1.2–5.9 kPa。木质部平均血管直径大的物种对VPD_叶片的g _s敏感性高。尽管物种之间的叶片水分关系存在显着变化，例如在膨松损失点的相对含水量（RWC _tlp）和在膨松损失点的水势（_Ψtlp），但这些水分关系与气孔敏感性无关到VPD_叶。在本研究的热带湿润森林中，VPD_叶片是9种树种中g _s的主要调节剂。g _s对VPD_叶片的高敏感性在具有较大容器面积的树木中，在整个气温变化期间，全天可能会维持适当的叶片水分状况，例如高水平的Ψ_叶。