Bedrock Modulates the Elevational Patterns of Soil Microbial Communities

Abstract

Elevational gradients are often used to reveal how soil microorganisms will respond to climate change. However, inconsistent microbial distribution patterns across different elevational transects have raised doubts about their universal applicability. We believe that variations in bedrock, which influence soil's physical and chemical properties, may explain these inconsistencies. We therefore investigated soil microbial communities (bacterial and fungal) along two adjacent elevational transects with different bedrocks (granite vs. slate) in a subtropical forest. Bedrock type not only influenced soil microbial biomass and community composition directly, but also governed microbial distribution patterns along the elevational gradients. Bacterial biomass was higher on slate, whereas fungal biomass was higher on granite. Both bacterial and fungal biomass increased with elevation on granite yet displayed different trends on slate. Bedrock type and elevation exerted weak influences on microbial α-diversity and strong influences on microbial beta-diversity. On granite, beta-diversity was influenced by soil total phosphorus and moisture, whereas on slate beta-diversity was influenced by soil organic carbon and pH. Our results confirm the importance of soil phosphorus, moisture, and pH levels to soil microbial community structure and reveal the critical role bedrock plays in shaping soil microbial communities along elevational gradients and thus the potential responses of soil microbial communities to changing climates.

Keywords: Altitude, climate, granite, parental material, slate, soil microbes