Soil C/N ratio governs bacterial community assembly along an arid mountain elevational gradient

Area of Science:

• Microbial Ecology
• Soil Science
• Biogeography

Background:

• Soil bacterial communities are crucial for fragile cold-arid mountain ecosystems.
• Mechanisms of bacterial community assembly along elevational gradients are poorly understood.

Purpose of the Study:

• Investigate bacterial community assembly mechanisms along an elevational gradient in the Central Kunlun Mountains.
• Identify key environmental drivers shaping soil bacterial diversity and community structure.

Main Methods:

• Analyzed soil bacterial communities across an elevational gradient (1,707–3,548 m).
• Assessed relationships between bacterial diversity (alpha and beta) and environmental factors (precipitation, vegetation, soil pH, C/N ratio).
• Utilized phylogenetic clustering to infer community assembly processes.

Main Results:

• Bacterial alpha-diversity increased with elevation; beta-diversity showed a hump-shaped pattern.
• Mean annual precipitation and vegetation cover were primary drivers, stronger than soil pH.
• Soil organic carbon-to-nitrogen ratio emerged as the dominant factor after accounting for multicollinearity.
• Higher elevations showed increased phylogenetic clustering, indicating deterministic selection linked to vegetation.

Conclusions:

• Vegetation plays a pivotal role in mediating bacterial community assembly by modulating the soil C/N ratio in arid mountains.
• Stochastic processes still dominate overall bacterial assembly, despite deterministic influences at higher elevations.
• Findings refine microbial biogeographic models, emphasizing vegetation-soil stoichiometry interplay under environmental stress for predicting climate change impacts.