Under climate change, extreme droughts will limit water availability for plants. However, the species-specific responses make it difficult to draw general conclusions. We hypothesized that changes in species' abundance in response to extreme drought can be best explained by a set of water economic traits under ambient conditions in combination with the ability to adjust these traits towards higher drought resistance. We conducted a 4-year field experiment in temperate grasslands using rainout shelters with 30% and 50% rainfall reduction. We quantified the response as the change in species abundance between ambient conditions and the rainfall reduction. Abundance response to extreme drought was best explained by a combination of traits in ambient conditions and their functional adjustment, most likely reflecting plasticity. Smaller leaved species decreased less in abundance under drought. With increasing drought intensity, we observed a shift from drought tolerance, i.e., an increase in leaf dry matter content, to avoidance, i.e., a less negative turgor loss point (TLP) in ambient conditions and a constancy in TLP under drought. We stress the importance of using a multidimensional approach of variation in multiple traits and the importance of considering a range of drought intensities to improve predictions of species' response to climate change.

中文翻译：

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极端干旱下功能性状及其可塑性从耐受性转变为回避性

在气候变化的情况下，极端干旱将限制植物可用的水资源。然而，物种特异性反应使得很难得出一般性结论。我们假设，物种丰度因极端干旱而发生的变化可以通过环境条件下的一组水经济特性以及调整这些特性以提高抗旱性的能力来最好地解释。我们使用避雨棚在温带草原进行了为期 4 年的野外试验，该避雨棚可减少 30% 和 50% 的降雨量。我们将响应量化为环境条件和降雨减少之间物种丰度的变化。对极端干旱的丰度反应最好用环境条件特征及其功能调整的组合来解释，很可能反映了可塑性。在干旱条件下，小叶物种的丰度下降较少。随着干旱强度的增加，我们观察到从耐旱性（即叶片干物质含量增加）转变为避免干旱（即环境条件下负膨压损失点 (TLP) 较少）和干旱条件下 TLP 的恒定性。我们强调了使用多维变异方法的重要性，以及考虑一系列干旱强度以改进物种对气候变化响应的预测的重要性。