Response of ecosystem nitrogen cycle to elevated CO2: A meta-analysis

Background/Question/Methods

Carbon (C) sequestration in terrestrial ecosystems largely depends on nitrogen (N) availability in response to rising atmospheric CO₂, which would result in progressive N limitation (PNL) that C and N are simultaneously fixed in long-lived plant biomass and soil organic matter. Hence, it is critical to examine how N processes respond to elevated CO₂ to alleviate PNL.  Here we evaluated the central tendencies of the responses of several variables associated with ecosystem N cycle to elevated CO₂, using data extracted from peer-reviewed papers. 

Results/Conclusions

Our results showed that elevated CO₂ induced uptake of inorganic N, hence reduce inorganic nitrogen leaching by around 20% under elevated CO₂. N addition may trigger this effect, which results in a 40% reduction under elevated CO₂ compared with ambient CO₂. However, only N addition increased inorganic nitrogen leaching by 150%.  Elevated CO₂ also affected N mineralization, N₂O flux, nitrification, and denitrification.  Our results indicate that elevated CO₂ may alleviate PNL through reduce leaching pathway.