Short-term Effects of Nitrogen Additions and Increased Temperature on Wetland Soil Respiration, Sanjiang Plain, China

Nitrogen deposition and global warming each have potential to alter soil carbon storage via changing decomposition, but combined effects of N addition and temperature on CO 2 production in wetland soils are less studied. In this study, we conducted laboratory incubations to examine this problem using soil from a freshwater marsh in Sanjiang Plain, China. We found that N addition and temperature had a negative and positive effect on CO 2 production, respectively. Despite low decomposition rates, heavy fractions had a notable contribution to CO 2 production due to greater mass proportion in soil. Short-term combined effect of N addition and temperature on CO 2 production was antagonistic. Based on greater N availability as N addition and temperature increasing, extra release of soil-derived N may further suppress CO 2 production. We suggest that short-term soil CO 2 production under simultaneous influence of temperature and N addition may be overestimated based on their single effects in this site.