Soil Microbial Communities Along Elevational Gradients in the Sky Islands

Abstract

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, the soil environment strongly influenced microbial community composition along elevation. In particular, our results suggest that warming might increase the abundance of soil-borne fungal plant pathogens that concomitantly might facilitate plants’ upward elevational shifts. Furthermore, projected warming and drought in the area aggravated by anthropogenic nitrogen deposition on mountain tops might 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.