TY - JOUR
T1 - Dominant role of nitrogen stoichiometric flexibility in ecosystem carbon storage under elevated CO2
AU - Zou, Junliang
AU - Li, Qianyu
AU - Osborne, Bruce
AU - Luo, Yiqi
N1 - Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/12/10
Y1 - 2020/12/10
N2 - 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.
AB - 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.
KW - Carbon sequestration
KW - C–N interaction
KW - Global change
KW - Meta-analysis
KW - Nitrogen
KW - Stoichiometry
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U2 - 10.1016/j.scitotenv.2020.141308
DO - 10.1016/j.scitotenv.2020.141308
M3 - Article
C2 - 32771790
AN - SCOPUS:85089032695
SN - 0048-9697
VL - 747
JO - Science of the Total Environment
JF - Science of the Total Environment
M1 - 141308
ER -