Nitrogen addition alters litter chemical traits to regulate decomposition: A meta-analysis

Area of Science:

• Ecology
• Biogeochemistry
• Environmental Science

Background:

• Litter chemical traits influence decomposition rates, responding to atmospheric nitrogen (N) deposition.
• The exact impact of N enrichment on litter chemistry and decomposition mechanisms remains unclear.

Purpose of the Study:

• To quantify the effects of N addition on litter chemistry and decomposition rates across various ecosystems.
• To investigate the mechanistic roles of litter traits in decomposition under N enrichment.

Main Methods:

• A meta-analysis synthesizing data from 80 studies on N addition experiments.
• Analysis of changes in litter N, phosphorus (P), lignin, cellulose, hemicellulose, and stoichiometric ratios (C/N, lignin/N).
• Correlation analysis between decomposition rates (k) and initial litter traits.

Main Results:

• N addition significantly increased litter N (+34.6%) and P (+18.5%), while decreasing lignin, cellulose, and hemicellulose.
• Litter quality improved, indicated by decreased C/N (-23.8%) and lignin/N (-25.4%) ratios.
• Herbaceous litter decomposition accelerated in grasslands, but woody litter decomposition was unaffected or inhibited in forests.

Conclusions:

• Plant functional types and ecosystems mediate decomposition responses to N deposition.
• Grasslands show accelerated decomposition due to improved litter quality, while forests experience microbial suppression.
• Integrating trait-mediated mechanisms is crucial for refining biogeochemical models of carbon and nutrient cycling under N enrichment.