Dominant role of nitrogen stoichiometric flexibility in ecosystem carbon storage under elevated CO2

Junliang Zou, Qianyu Li, Bruce Osborne, Yiqi Luo

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Interactions between the carbon (C) and nitrogen (N) cycles can impact on the sensitivity of terrestrial C storage to elevated atmospheric carbon dioxide (CO2) concentrations (eCO2). However, the underlying mechanisms associated with C–N interactions that influence terrestrial ecosystem C sequestration (Cseq) remains unclear. Here, we quantitatively analyzed published C and N responses to experimentally eCO2 using a meta-analysis approach. We determined the relative importance of three principal mechanisms (changes in the total ecosystem N amount, redistribution of N between plant and soil pools, and flexibility of the C:N ratio) that contribute to increases in ecosystem C storage in response to eCO2. Our results showed that eCO2 increased C and N accumulation, resulted in higher C:N ratios in plant, litter, and soil pools and induced a net shift of N from soils to vegetation. These three mechanisms largely explained the increment of ecosystem Cseq under eCO2, although the relative contributions differed across ecosystem types, with changes in the C:N ratio contributing 50% of the increment in forests Cseq, while the total N change contributed 60% of the increment in grassland Cseq. In terms of temporal variation in the relative importance of each of these three mechanisms to ecosystem Cseq: changes in the C:N ratio was the most important mechanism during the early years (~5 years) of eCO2 treatment, whilst the contribution to ecosystem Cseq by N redistribution remained rather small, and the contribution by total N change did not show a clear temporal pattern. This study highlights the differential contributions of the three mechanisms to Cseq, which may offer important implications for future predictions of the C cycle in terrestrial ecosystems subjected to global change.

Original languageEnglish (US)
Article number141308
JournalScience of the Total Environment
Volume747
DOIs
StatePublished - Dec 10 2020

Keywords

  • Carbon sequestration
  • C–N interaction
  • Global change
  • Meta-analysis
  • Nitrogen
  • Stoichiometry

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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