A global perspective on belowground carbon dynamics under nitrogen enrichment

Area of Science:

• Ecology
• Biogeochemistry
• Soil Science

Background:

• Ecosystem carbon (C) budgets are crucial for understanding climate change mitigation, particularly C sequestration's role in offsetting anthropogenic CO2 emissions.
• While aboveground carbon and nitrogen (N) cycling is well-understood, belowground processes require further investigation.
• Nitrogen deposition is a significant global change factor impacting terrestrial ecosystems.

Purpose of the Study:

• To quantify the effects of nitrogen addition on belowground carbon cycling across diverse terrestrial ecosystems.
• To synthesize existing data through meta-analysis to identify trends and patterns.

Main Methods:

• Meta-analysis of data from multiple terrestrial ecosystems.
• Quantification of belowground carbon cycling responses to nitrogen addition.
• Assessment of changes in litter input, microbial activity, soil respiration, dissolved organic carbon, and soil carbon content.

Main Results:

• Nitrogen addition increased aboveground litter input by 20% but did not affect fine root input.
• Microbial respiration decreased by 8% and microbial biomass carbon by 20%.
• Dissolved organic carbon increased by 18%, suggesting potential for increased C leaching.
• Organic layer carbon content increased by 17%, while mineral soil layer carbon content remained unchanged.

Conclusions:

• Nitrogen addition enhances short-term belowground carbon storage by increasing organic layer carbon content.
• The long-term effects of nitrogen addition on ecosystem carbon sequestration are difficult to predict due to the lack of significant changes in mineral soil carbon content.