1. Increased drought is predicted to have a major impact on plant performance under environmental change. Yet leaf hydraulic traits directly related to drought tolerance, such as leaf turgor loss point (π_tlp), are under-represented in trait-based studies and have been largely overlooked within the main frameworks evaluating trait–trait coordination and trade-offs—the leaf economics spectrum (LES) and the global spectrum of plant form and function.
2. Using 122 herbaceous species from the Central European temperate grasslands, we investigated (a) the coordination between π_tlp and traits often used as proxies for drought tolerance, namely SLA, leaf area (LA), leaf dry matter content (LDMC), leaf thickness (LT), plant height and intrinsic water use efficiency (iWUE); (b) whether the strength of the trait–trait relationships differed across plant functional types (PFTs: graminoids and forbs) and depended on species phylogeny; and (c) whether single or multiple traits, combined with either PFTs or phylogenetic relatedness, provide a good prediction of π_tlp.
3. A more negative π_tlp (higher leaf drought tolerance) was coordinated with higher LDMC and higher iWUE. This pattern was consistent among PFTs and also after accounting for phylogenetic relatedness. However, the coordination of π_tlp with other traits was weak. For LT and height, it was driven by the differences between PFTs. For SLA and LA, it was only observed after accounting for phylogenetic relatedness.
4. The most parsimonious model predicting π_tlp as a function of other traits retained LDMC and LA (adj. R² = 0.37). Since π_tlp showed a strong phylogenetic signal, accounting for the influence of phylogenetic relatedness further improved π_tlp prediction by 17%.
5. In herbaceous temperate plants, there is relatively weak coordination between leaf drought tolerance (π_tlp) and traits representing key dimensions of the LES and the global spectrum of plant form and function. None of the proxy traits considered here, alone or in combination, provided a strong prediction of π_tlp across a large number of grassland plant species. Therefore, our work emphasizes the need for direct measurements of leaf hydraulics when estimating plant drought responses to better understand and predict species responses to environmental change.

中文翻译：

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草本植物叶片耐旱性与代理性状之间的弱协调

1. 预计干旱加剧将对环境变化下的植物性能产生重大影响。然而，与耐旱性直接相关的叶片水力性状，例如叶片膨压损失点 ( π _tlp )，在基于性状的研究中代表性不足，并且在评估性状-性状协调和权衡的主要框架中被很大程度上忽视了——叶经济学谱 (LES) 和植物形态和功能的全球谱。
2. 使用来自中欧温带草原的 122 种草本植物，我们研究了 (a) π _tlp与通常用作耐旱性代理的性状之间的协调，即 SLA、叶面积 (LA)、叶干物质含量 (LDMC)、叶厚度(LT)、植物高度和内在水分利用效率 (iWUE)；(b) 性状-性状关系的强度是否因植物功能类型（PFT：禾本科和异形）而异，并取决于物种系统发育；(c) 无论是单个还是多个性状，结合 PFT 或系统发育相关性，都可以很好地预测π _tlp。
3. 更负的π _tlp（更高的叶片耐旱性）与更高的 LDMC 和更高的 iWUE 相协调。这种模式在 PFT 之间是一致的，并且在考虑到系统发育相关性之后也是如此。然而，π _tlp与其他性状的协调性很弱。对于 LT 和高度，它是由 PFT 之间的差异驱动的。对于 SLA 和 LA，仅在考虑系统发育相关性后才观察到。
4. 预测π _tlp作为其他特征的函数的最简约模型保留了 LDMC 和 LA（调整R ²  = 0.37）。由于π _tlp显示出强烈的系统发育信号，考虑到系统发育相关性的影响，π _tlp预测进一步提高了 17%。
5. 在温带草本植物中，叶片耐旱性 ( π _tlp ) 与代表 LES 关键维度的性状以及植物形态和功能的全球谱之间的协调性相对较弱。这里考虑的代理性状，无论是单独还是组合，都没有提供对大量草原植物物种的π _tlp的强预测。因此，我们的工作强调在估计植物干旱响应时需要直接测量叶片水力学，以更好地理解和预测物种对环境变化的响应。