Stimulation of soil respiration by elevated CO2 is enhanced under nitrogen limitation in a decade-long grassland study

Qun Gao, Gangsheng Wang, Kai Xue, Yunfeng Yang, Jianping Xie, Hao Yu, Shijie Bai, Feifei Liu, Zhili He, Daliang Ning, Sarah E. Hobbie, Peter B. Reich, Jizhong Zhou

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


Whether and how CO2 and nitrogen (N) availability interact to influence carbon (C) cycling processes such as soil respiration remains a question of considerable uncertainty in projecting future C–climate feedbacks, which are strongly influenced by multiple global change drivers, including elevated atmospheric CO2 concentrations (eCO2) and increased N deposition. However, because decades of research on the responses of ecosystems to eCO2 and N enrichment have been done largely independently, their interactive effects on soil respiratory CO2 efflux remain unresolved. Here, we show that in a multifactor free-air CO2 enrichment experiment, BioCON (Biodiversity, CO2, and N deposition) in Minnesota, the positive response of soil respiration to eCO2 gradually strengthened at ambient (low) N supply but not enriched (high) N supply for the 12-y experimental period from 1998 to 2009. In contrast to earlier years, eCO2 stimulated soil respiration twice as much at low than at high N supply from 2006 to 2009. In parallel, microbial C degradation genes were significantly boosted by eCO2 at low but not high N supply. Incorporating those functional genes into a coupled C–N ecosystem model reduced model parameter uncertainty and improved the projections of the effects of different CO2 and N levels on soil respiration. If our observed results generalize to other ecosystems, they imply widely positive effects of eCO2 on soil respiration even in infertile systems.

Original languageEnglish (US)
Pages (from-to)33317-33324
Number of pages8
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number52
StatePublished - Dec 29 2020

Bibliographical note

Publisher Copyright:
© 2020 National Academy of Sciences. All rights reserved.


  • Earth ecosystem model
  • Elevated CO
  • Metagenomics
  • Nitrogen deposition
  • Soil respiration
  • Grassland
  • Nitrogen/pharmacology
  • Aerobiosis
  • Soil/chemistry
  • Soil Microbiology
  • Computer Simulation
  • Carbon Dioxide/pharmacology

PubMed: MeSH publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Journal Article


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