Data for: Phenotypic variation of hydraulic traits for woody species

Hydraulic traits are major determinants of plant fitness, thus exerting control over vegetation structure, function and distribution. Yet it remains unclear whether and how hydraulic traits respond to environmental stimuli (i.e., phenotypic variation of hydraulic traits; PVHT), and if the coordination between different hydraulic traits and the trait-climate relationship are affected by PVHT.

Here, we synthesized data of PVHT (maximum hydraulic conductivity and water potential inducing 50% loss of hydraulic conductivity) as well as potentially related morphological and anatomical traits (e.g. sapwood density, branch Huber value, mean and hydraulic weighted conduit diameter). We analyzed the magnitude, direction and source of variation of the plastic response, as well as the influence of environmental factors on trait coordination. Additionally, we compared the intra- and inter- specific variation between key hydraulic traits and climate metrics (mean annual precipitation and mean annual temperature) at the site of growth, as well as across the population range.

PVHT was highly variable in both magnitude and direction, which was contingent on the environmental factor. The variation in PVHT mainly occurred at high taxonomic levels (i.e., family and genus), whereas phenology explained little variation for PVHT. Despite the high variability, trait correlation remained robust in the presence of environmental stimuli. Moreover, trait-climate relationships differed at inter-specific and intra-specific levels. The intra-specific variation of hydraulic traits in most species showed no correlation with climate metrics compared with the high correlation of hydraulic traits with climate metrics across species.

Our findings suggest that the high variability of PVHT does not affect the trait correlation which may be valuable in predicting vegetation dynamics under varying environments. The distinct trait-climate relationships highlight the need to unravel the driving force of PVHT, as well as the adaptive strategy across populations.

水力性状（hydraulic traits）是植物适合度的主要决定因素，进而对植被结构、功能与分布格局施加调控作用。然而目前仍不明确水力性状是否以及如何响应环境刺激（即水力性状表型变异（phenotypic variation of hydraulic traits, 简称PVHT）），同时也不清楚不同水力性状间的协同关系以及性状-气候关联是否会受到PVHT的影响。

本研究整合了PVHT相关数据集（涵盖最大导水率与导致50%导水率损失的水势），以及潜在相关的形态与解剖性状数据（如边材密度、枝条Huber值、平均导管直径与水力加权导管直径）。我们分析了表型塑性响应的变异幅度、方向与来源，同时探究了环境因子对性状协同关系的影响。此外，我们还对比了在生长位点以及种群分布范围内，关键水力性状与气候指标（年平均降水量、年平均气温）之间的种内与种间变异差异。

研究结果表明，PVHT在变异幅度与方向上均存在显著差异，且该变异受环境因子调控。PVHT的变异主要集中在较高的分类学层级（即科与属水平），而物候对PVHT变异的解释贡献率极低。尽管存在高度变异，但在环境刺激下，性状间的相关性仍保持稳健。此外，性状-气候关联在种间与种内水平上存在显著差异：相较于跨物种水平上水力性状与气候指标的高度相关性，多数物种的水力性状种内变异与气候指标并无显著关联。

本研究结果表明，PVHT的高度变异并不会破坏性状间的协同关系，这一发现对于预测多变环境下的植被动态具有重要参考价值。而性状-气候关联的显著差异，则凸显了阐明PVHT驱动机制以及跨种群适应策略的必要性。