Long-term nitrogen deposition enhances microbial capacities in soil carbon stabilization but reduces network...

Area of Science:

• Ecology
• Soil Science
• Microbiology

Background:

• Anthropogenic activities increase atmospheric reactive nitrogen (N) inputs into terrestrial ecosystems.
• Nitrogen deposition impacts soil carbon stability and microbial communities.
• Previous research focused on microbial taxonomy and enzymatic activities under nitrogen enrichment.

Purpose of the Study:

• To investigate the functional traits of soil microbial communities under long-term nitrogen (N) amendment.
• To understand the interrelationships of these traits in a Mediterranean-type grassland.
• To assess the impact of estimated future N deposition levels.

Main Methods:

• Analysis of soil microbial functional traits after 14 years of N amendment (7 g m⁻² year⁻¹).
• Assessment of microbial community structure and gene abundances related to carbon (C) degradation.
• Evaluation of microbial network complexity and connectivity.

Main Results:

• Nitrogen deposition significantly altered soil microbial communities, favoring fast-growing bacteria.
• Increased relative abundance of genes for labile C degradation (e.g., amyA, cda).
• Reduced microbial network complexity and increased connectivity among C degradation genes.

Conclusions:

• Long-term nitrogen deposition promotes soil carbon accumulation.
• Changes in above- and belowground ecosystems drive these effects.
• A conceptual model illustrates the mechanisms of soil carbon accumulation under nitrogen enrichment.