To improve projections of consequences of increasing intensity and frequency of drought events for grasslands, we need a thorough understanding of species performance responses to drought, of performance trade-offs and how drought resistance is related to species distributions. However, comparative and quantitative assessments of whole-plant drought resistance that allow to rigorously address these aspects are lacking for temperate grassland species. We conducted a common garden experiment with 40 common temperate grassland species to compare species survival and growth under intense drought and well-irrigated conditions. Overall, survival and growth were significantly reduced under drought, with the effect varying across species. Species ranking of drought damage and survival remained consistent with progressing drought. No performance trade-offs emerged between optimal growth and drought resistance of survival ('growth-stress tolerance' trade-off hypothesis), or between growth under well-watered and dry conditions ('growth rates' trade-off hypothesis). Species local- and large-scale association with moisture (Ellenberg F value and rainfall niche) was not related to their drought resistance. Overall, our results imply that trade-offs and differences of species fundamental drought resistance are not the main drivers of hydrological niche differentiation, species coexistence and their distribution across moisture gradients. The comparative experimental assessment of species whole-plant drought responses we present provides a basis to increase our understanding of current grassland responses to variation of moisture regimes and for projecting consequences of future changes.

中文翻译：

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温带草原物种的比较抗旱性：测试性能的取舍及其与分布的关系。

为了改善对干旱发生强度和频率增加的后果的预测，我们需要对物种对干旱的性能反应，性能折衷以及抗旱性与物种分布之间的关系有透彻的了解。但是，对于温带草原物种，缺乏能够严格解决这些方面的全植物抗旱性的比较和定量评估。我们对40种常见的温带草原物种进行了一项常见的花园实验，以比较在强烈干旱和灌溉条件下物种的生存和生长。总体而言，干旱导致生存和生长显着降低，其影响因物种而异。干旱破坏和生存的物种等级与干旱的进行保持一致。在最佳生长与生存的抗旱性（“生长压力耐性”的平衡假设）之间，或在水分充足和干燥条件下的生长之间（“生长速率”的平衡假设）之间，没有表现上的平衡。物种与水分的局部和大规模关联（Ellenberg F值和降雨位）与它们的抗旱性无关。总体而言，我们的结果表明，物种基本抗旱性的权衡和差异并不是水文生态位分化，物种共存及其在湿度梯度上的分布的主要驱动力。