Investigation of leaf water enrichment may improve our understanding of evapotranspiration partitioning and material exchange between the inside and the outside of leaves. In this study, with measurements of diel variations in δ¹⁸O of bulk leaf water (δ_L,b) of Platycladus orientalis, two theories (the Péclet effect and the two-pool model) describing leaf water enrichment were assessed. The proportional difference between observed and modeled leaf water enrichment, f, was estimated using both isotopic-steady-state (ISS) and non-steady-state (NSS) models to test the two theories. The results showed that differences between ISS- and NSS-modeled leaf water enrichment at the evaporative sites (Δ_l,e) were not significant (p > 0.05), thus estimated f was not significantly (p > 0.05) influenced by assuming ISS or NSS conditions. Under both ISS and NSS conditions, no significant (P > 0.05) positive f–T_r (leaf transpiration rate) relationships were found on either diel or diurnal time scales, indicating that the Péclet effect is not required to describe bulk leaf water enrichment. Therefore, it would be adequate to combine the simple two-pool model with the ISS model to predict δ¹⁸O of bulk leaf water of P. orientalis. These results may have implications for parameterizing the carbon cycle, past climates, and evapotranspiration partitioning models.

对叶片水分富集的研究可能会提高我们对蒸散分配和叶片内部与外部之间的物质交换的理解。在这项研究中，与昼夜变化的测量δ ¹⁸的散装叶水O（δ _L，B的）侧柏描述叶水富集，两种理论（佩克莱特效果和两池模型）进行了评估。使用同位素稳态（ISS）模型和非稳态（NSS）模型来评估这两种理论，从而估算和模拟叶水富集度f之间的比例差异。结果表明，蒸发位点的ISS模型和NSS模型叶片水分富集之间的差异（Δl _，e）并不显着（p  > 0.05），因此 ，假设ISS或NSS条件对估计的f的影响不显着（p > 0.05）。在ISS和NSS条件下，在diel或昼夜时间尺度上均未发现显着（P  > 0.05）的正f - T _r（叶蒸腾速率）正相关，表明不需要Péclet效应来描述大量叶片水分的富集。因此，这将是足够简单的两库模式与国际空间站的模型相结合，预测δ ¹⁸的散叶水Ø侧柏。这些结果可能对参数化碳循环，过去的气候和蒸散模型具有影响。