High rates of climate change are currently exceeding many plant species' capacity to keep up with climate, leading to mismatches between climatic conditions and climatic preferences of the species present in a community. This disequilibrium between climate and community composition could diminish, however, when critical climate thresholds are exceeded, due to population declines or losses among the more mismatched species. Here, we assessed the effect of an extreme drought event on rich semiarid shrubland communities in the south‐eastern Iberian Peninsula. Using a community climate framework, we compared the community climatic disequilibrium before and after the drought episode on three study sites with different levels of precipitation. Disequilibrium was estimated as the difference between observed reference climate and community‐inferred climate, calculated as the mean climatic optimum for the species present, weighted by their abundances. We found that extreme drought embedded within a decadal trend of increasing aridity led to a significant reduction in community climatic disequilibrium, and that this reduction was positively related to water deficit (low P/PET values). In contrast, microhabitat variables such as vegetation cover or slope, did not emerge as significant predictors of changes in community climatic disequilibrium. Our study highlights that extreme drought events pushing communities in the same direction as climate trends may decrease community climatic mismatch, leading to communities more adapted to aridity through loss of drought‐sensitive species. These findings underscore that extreme events will play a crucial role in speeding up climate‐induced community transformations and biodiversity losses.

中文翻译：

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极端干旱减少了旱地植物群落的气候不平衡

当前，高气候变化率已超出许多植物物种适应气候的能力，导致气候条件与社区中物种的气候偏好之间不匹配。但是，当气候临界点超过临界阈值时，由于种群数量的减少或失配造成的损失，这种气候和群落组成之间的不平衡可能会减弱。在这里，我们评估了极端干旱事件对东南伊比利亚半岛丰富的半干旱灌木丛群落的影响。使用社区气候框架，我们比较了三个降水量不同的研究地点干旱发生前后的社区气候失衡。不平衡被估计为观察到的参考气候与社区推断的气候之间的差异，计算为存在物种的平均气候最佳值，并由其丰富度加权。我们发现，干旱加剧的年代际趋势中所包含的极端干旱导致了社区气候不平衡的显着减少，并且这种减少与水分亏缺（低P / PET值）呈正相关。相比之下，诸如植被覆盖度或坡度之类的微生境变量并没有成为社区气候失衡变化的重要预测指标。我们的研究突出表明，极端干旱事件将社区推向与气候趋势相同的方向，这可能会减少社区的气候失配，从而导致社区通过减少对干旱敏感的物种而更加适应干旱。