Publication Abstracts

Du et al. 2018

Du, Z., E. Weng, L. Jiang, Y. Luo, J. Xia, and X. Zhou, 2018: Carbon-nitrogen coupling under three schemes of model representation: A traceability analysis. Geosci. Model Dev., 11, 4399-4416, doi:10.5194/gmd-11-4399-2018.

The interaction between terrestrial carbon (C) and nitrogen (N) cycles has been incorporated into more and more land surface models. However, the scheme of C-N coupling differs greatly among models, and how these diverse representations of C-N interactions will affect C-cycle modeling remains unclear. In this study, we explored how the simulated ecosystem C storage capacity in the terrestrial ecosystem (TECO) model varied with three different commonly used schemes of C-N coupling. The three schemes (SM1, SM2, and SM3) have been used in three different coupled C-N models (i.e., TECO-CN, CLM 4.5, and O-CN, respectively). They differ mainly in the stoichiometry of C and N in vegetation and soils, plant N uptake strategies, downregulation of photosynthesis, and the pathways of N import. We incorporated the three C-N coupling schemes into the C-only version of the TECO model and evaluated their impacts on the C cycle with a traceability framework. Our results showed that all three of the C-N schemes caused significant reductions in steady-state C storage capacity compared with the C-only version with magnitudes of -23%, -30%, and -54% for SM1, SM2, and SM3, respectively. This reduced C storage capacity was mainly derived from the combined effects of decreases in net primary productivity (NPP; -29%, -15%, and -45%) and changes in mean C residence time (MRT; 9%, -17%, and -17%) for SM1, SM2, and SM3, respectively. The differences in NPP are mainly attributed to the different assumptions on plant N uptake, plant tissue C:N ratio, downregulation of photosynthesis, and biological N fixation. In comparison, the alternative representations of the plant vs. microbe competition strategy and the plant N uptake, combined with the flexible C:N ratio in vegetation and soils, led to a notable spread in MRT. These results highlight the fact that the diverse assumptions on N processes represented by different C-N coupled models could cause additional uncertainty for land surface models. Understanding their difference can help us improve the capability of models to predict future biogeochemical cycles of terrestrial ecosystems.

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BibTeX Citation

  author={Du, Z. and Weng, E. and Jiang, L. and Luo, Y. and Xia, J. and Zhou, X.},
  title={Carbon-nitrogen coupling under three schemes of model representation: A traceability analysis},
  journal={Geosci. Model Dev.},

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RIS Citation

ID  - du07100r
AU  - Du, Z.
AU  - Weng, E.
AU  - Jiang, L.
AU  - Luo, Y.
AU  - Xia, J.
AU  - Zhou, X.
PY  - 2018
TI  - Carbon-nitrogen coupling under three schemes of model representation: A traceability analysis
JA  - Geosci. Model Dev.
VL  - 11
SP  - 4399
EP  - 4416
DO  - 10.5194/gmd-11-4399-2018
ER  -

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