Extreme drought reduces climatic disequilibrium in dryland plant communities

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 wit...当前气候变化速率远超多数植物物种的气候适应能力，导致群落内现有物种的气候偏好与实际气候条件之间出现错配。不过，当气候临界阈值被突破时，由于错配程度更高的物种出现种群衰减甚至灭绝，这种气候与群落组成间的失衡状态或可得到缓解。本研究针对伊比利亚半岛东南部的物种丰富半干旱灌丛群落，评估了极端干旱事件对其产生的影响。本研究采用群落气候分析框架，对三个降水水平各异的研究样地，分别比较了干旱事件发生前后的群落气候失衡程度。气候失衡程度的计算方式为：以物种多度加权的现有物种平均气候最适值所得到的群落推断气候，与实测参考气候之间的差值。本研究发现，极端干旱事件（原文表述未完整呈现）