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Nitrogen Enrichment Reverses Microbial Biomass-Function Relationships Over Time in a Global Meta-Analysis
Kejie Li1, Jinyang Wang1,2, Zhenghu Zhou3
1Key Laboratory of Agricultural Green and Low-Carbon in Southeastern China, Ministry of Agriculture and Rural Affairs, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China.
Global Change Biology
|September 24, 2025
Summary
Atmospheric nitrogen (N) enrichment boosts ecosystem function but reduces microbial biomass long-term. Soil properties, not N deposition, drive these changes, highlighting microbial shifts and soil constraints.
Area of Science:
- Ecology
- Soil Science
- Microbiology
Background:
- Soil microbial communities are vital for ecosystem functions.
- Long-term effects of atmospheric nitrogen (N) enrichment on these communities are not well understood.
Purpose of the Study:
- To synthesize global data from N addition experiments.
- To evaluate ecosystem functionality and microbial responses to N enrichment.
- To map global responses and identify key drivers.
Main Methods:
- Synthesized data from 6255 paired observations across 308 field N addition experiments.
- Used multivariate linear mixed-effects models and meta-forest modeling.
- Analyzed responses across varying N addition rates and durations.
Main Results:
- N enrichment enhanced ecosystem functionality by 17.6% and reduced microbial biomass by 4.2%.
- Responses intensified with higher N rates and longer durations.
- Soil pH, sand content, and bulk density were primary spatial drivers, not N deposition.
- A temporal reversal in the microbial biomass-ecosystem functionality relationship was observed.
Conclusions:
- Microbial biomass is crucial for long-term ecosystem functionality under N enrichment.
- Shifts in microbial life-history strategies (oligotrophic to copiotrophic) are key.
- Soil properties significantly constrain ecological responses to sustained N enrichment.
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