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Published on: March 12, 2013
Nitrogen deposition weakens plant-microbe interactions in grassland ecosystems
Cunzheng Wei1, Qiang Yu, Edith Bai
1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Global Change Biology
|August 9, 2013
Summary
Nitrogen enrichment alters soil carbon and nitrogen ratios, impacting plant-soil-microbe interactions. Soil acidification, not plant changes, drives microbial shifts and respiration decline under high nitrogen.
Area of Science:
- Ecology
- Soil Science
- Biogeochemistry
Background:
- Soil carbon (C) and nitrogen (N) stoichiometry are critical for ecosystem function.
- Global nitrogen (N) enrichment significantly alters soil C:N ratios, affecting ecosystem processes.
- The impact of altered resource stoichiometry on plant-soil-microbe interactions remains under-explored.
Purpose of the Study:
- Investigate plant-soil-microbe system responses to multi-level N additions.
- Determine the role of dissolved organic carbon (DOC) and inorganic N stoichiometry in regulating microbial biomass.
- Understand how N enrichment affects interactions within semiarid grassland ecosystems.
Main Methods:
- Field experiment with multi-level nitrogen (N) additions.
- Analysis of soil carbon (C) and nitrogen (N) stoichiometry, including dissolved organic carbon (DOC) and inorganic N.
- Hierarchical structural equation modeling (SEM) to assess causal relationships.
- Measurement of plant community composition, microbial community composition, and microbial respiration.
Main Results:
- A positive correlation between DOC and inorganic N was observed across the N addition gradient, contrary to typical findings.
- Soil acidification, driven by N addition, was the primary factor linked to shifts in soil microbial community composition and reduced microbial respiration.
- Plant community changes were less influential on microbial communities than soil acidification.
Conclusions:
- High nitrogen availability down-regulates plant-microbe interactions by shifting the limiting factor for microbial biomass from resource stoichiometry to soil acidity.
- Nitrogen enrichment weakens the bottom-up control of soil microorganisms by plant-derived carbon sources.
- Integrative studies of the plant-soil-microbe system are essential for understanding ecosystem functioning under global N enrichment.
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