Elevation shapes the biogeography and assembly of soil microbial carbon-cycling functions in mountain ecosystems

Abstract

Soil microbial functional genes play a crucial role in regulating carbon (C) cycling in mountain ecosystems. Elevation gradients integrate concurrent changes in temperature, moisture, vegetation, and soil properties, providing a natural framework to examine how microbial carbon-cycling functions respond to environmental change. However, studies investigating the responses of soil microbial functional genes related to C cycling along elevation gradients remain limited. In this study, we examined the composition, diversity, and assembly mechanisms of carbohydrate-active enzymes (CAZymes) and other C cycle-related functional genes across different elevations in Changbai Mountain. Our results indicate that the relative abundance of CAZymes and C cycle genes increased overall with the elevation gradient. β-diversity analysis revealed that fungal communities were most sensitive to elevation changes. Furthermore, the species replacement of CAZymes and C cycle genes was strongly regulated by elevation. The community assembly of CAZymes and C cycle genes was predominantly driven by stochastic processes. Importantly, microbial diversity emerged as the strongest predictor of CAZymes and C cycle gene diversity. This result highlights the central role of microbial community structure in regulating soil carbon functional potential along elevation gradients. Overall, our findings provide new insights into the biogeographic patterns and assembly mechanisms of soil C functional genes in mountain ecosystems, thereby enhancing our understanding of C dynamics and providing guidance for organic carbon management under climate change.

Graphical abstract

Keywords

elevation gradient / biogeographic distribution / carbohydrate-active enzymes / carbon cycle genes / community assembly / mountain ecosystems

Highlight

	● Elevation significantly enhanced the abundance of CAZymes and C cycle genes.
	● C degradation and methanogenesis genes were more elevation-sensitive than carbon fixation.
	● Species replacement was the main driver for CAZymes and C cycle genes.
	● Stochastic processes dominated the assembly of carbon-cycling functions along elevation.
	● Microbial community was a key determinant of carbon-cycling functional diversity.

References

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