The Madrean Sky Islands are mountain ranges isolated by a ‘desert sea’. This area is a biodiversity hotspot currently threatened by climate change. Here, we studied soil microbial communities along elevational gradients in eight Madrean Sky Islands in southeastern Arizona (USA). Our results showed that while elevational microbial richness gradients were weak and not consistent across different mountains, soil properties strongly influenced microbial community composition (overall composition and the abundance of key functional groups) along elevational gradients. In particular, warming is associated with a higher abundance of soil‐borne fungal plant pathogens that concomitantly might facilitate upward elevational shifts of plant species released from negative plant–soil feedbacks. Furthermore, projected warming and drought in the area aggravated by anthropogenic nitrogen deposition on mountain tops (and thus, decreasing nitrogen limitation) can enhance a shift from ectomycorrhizal to arbuscular mycorrhizal fungi. Overall, these results indicate that climate change effects on plant–soil interactions might have profound ecosystem consequences.

中文翻译：

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马德雷天空群岛沿海拔梯度的土壤微生物群落

马德雷天空群岛是被“沙漠海”隔离的山脉。该地区是目前受到气候变化威胁的生物多样性热点地区。在这里，我们研究了美国亚利桑那州东南部八个马德雷安天空群岛沿海拔梯度的土壤微生物群落。我们的结果表明，虽然不同山脉的海拔微生物丰富度梯度较弱且不一致，但土壤性质强烈影响沿海拔梯度的微生物群落组成（总体组成和关键功能群的丰度）。特别是，变暖与土传真菌植物病原体的丰度增加有关，同时可能促进植物-土壤负反馈释放的植物物种向上移动。此外，预计该地区的变暖和干旱会因山顶上的人为氮沉积而加剧（从而减少氮限制），这可能会促进外生菌根真菌向丛枝菌根真菌的转变。总体而言，这些结果表明气候变化对植物-土壤相互作用的影响可能会对生态系统产生深远的影响。