OOS 47-10 - A global perspective on below-ground carbon dynamics under nitrogen enrichment

Thursday, August 5, 2010: 4:40 PM
310-311, David L Lawrence Convention Center
Lingli Liu, State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China and Tara L. Greaver, National Center for Environmental Assessment, US Environmental Protection Agency, Research Triangle Park, NC
Background/Question/Methods

Nitrogen (N) effects on ecosystem carbon (C) budgets are critical to understand as C sequestration is considered as a mechanism to offset anthropogenic CO2 emissions. Interactions between aboveground C and N cycles are more clearly characterized than belowground processes. Through synthesizing data from multiple terrestrial ecosystems, we quantified the responses of belowground C cycling under N addition.
Results/Conclusions

We found that N addition increased litter input from aboveground (+20%) but not litter input from fine root. N addition inhibited microbial activity as indicated by a reduction in microbial respiration (-8%) and microbial biomass carbon (-20%). Although soil respiration was not altered by N addition, dissolved organic carbon (DOC) concentration was increased by 18%, suggesting C leaching loss may increase. N addition increased the C content of the organic layer (+17%) but not the mineral soil layer. Overall, our meta-analysis indicates that N addition will increase short-term belowground C storage by increasing C content of organic layer.  However, it is difficult to predict the response of long-term C sequestration since there is no significant change in mineral soil C content.

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