• Climate extremes pose enormous threats to natural ecosystems. Arbuscular mycorrhizal (AM) fungi are key plant symbionts that can affect plant community dynamics and ecosystem stability. However, knowledge about how AM fungal communities respond to climate extremes in natural ecosystems remains elusive.
• Based on a grassland extreme drought experiment in Inner Mongolia, we investigated the response of AM fungal communities to extreme drought in association with plant communities. The experiment simulated two types of extreme drought (chronic/intense) of once-in-20-year occurrence.
• AM fungal richness and community composition exhibited high sensitivity to extreme drought and were more sensitive to intense drought than chronic drought. This community sensitivity (i.e. decline in richness and shifts in community composition) of AM fungi can be jointly explained by soil moisture, plant richness, and aboveground productivity. Notably, the robustness of the plant–AM fungal community co-response increased with drought intensity.
• Our results indicate that AM fungal communities are sensitive to climate extremes, and we propose that the plant community mediates AM fungal community responses. Given the ubiquitous nature of AM associations, their climate sensitivity may have profound consequences on plant communities and ecosystem stability under climate change.

中文翻译：

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丛枝菌根真菌对寒温带草原极端干旱的群落响应

• 极端气候对自然生态系统构成巨大威胁。丛枝菌根 (AM) 真菌是影响植物群落动态和生态系统稳定性的关键植物共生体。然而，关于 AM 真菌群落如何应对自然生态系统中的极端气候的知识仍然难以捉摸。
• 基于内蒙古草原极端干旱实验，我们调查了 AM 真菌群落对极端干旱与植物群落相关的响应。该实验模拟了 20 年一遇的两种极端干旱（慢性/强烈）。
• AM 真菌丰富度和群落组成对极端干旱表现出高度敏感性，并且对强烈干旱比对慢性干旱更敏感。AM 真菌的这种群落敏感性（即丰富度下降和群落组成变化）可以用土壤水分、植物丰富度和地上生产力共同解释。值得注意的是，植物-AM 真菌群落共同响应的稳健性随着干旱强度的增加而增加。
• 我们的结果表明 AM 真菌群落对极端气候很敏感，我们建议植物群落介导 AM 真菌群落的反应。鉴于 AM 关联无处不在，它们的气候敏感性可能对气候变化下的植物群落和生态系统稳定性产生深远影响。