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Carbon-nitrogen interactions in idealized simulations with JSBACH (version 3.10)

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Title: Carbon-nitrogen interactions in idealized simulations with JSBACH (version 3.10)
Authors: Goll, DS
Winkler, AJ
Raddatz, T
Dong, N
Prentice, IC
Ciais, P
Brovkin, V
Item Type: Journal Article
Abstract: Recent advances in the representation of soil carbon decomposition and carbon–nitrogen interactions implemented previously into separate versions of the land surface scheme JSBACH are here combined in a single version, which is set to be used in the upcoming 6th phase of coupled model intercomparison project (CMIP6). Here we demonstrate that the new version of JSBACH is able to reproduce the spatial variability in the reactive nitrogen-loss pathways as derived from a compilation of δ15N data (R = 0. 76, root mean square error (RMSE)  = 0. 2, Taylor score  = 0. 83). The inclusion of carbon–nitrogen interactions leads to a moderate reduction (−10 %) of the carbon-concentration feedback (βL) and has a negligible effect on the sensitivity of the land carbon cycle to warming (γL) compared to the same version of the model without carbon–nitrogen interactions in idealized simulations (1 % increase in atmospheric carbon dioxide per year). In line with evidence from elevated carbon dioxide manipulation experiments, pronounced nitrogen scarcity is alleviated by (1) the accumulation of nitrogen due to enhanced nitrogen inputs by biological nitrogen fixation and reduced losses by leaching and volatilization. Warming stimulated turnover of organic nitrogen further counteracts scarcity. The strengths of the land carbon feedbacks of the recent version of JSBACH, with βL = 0. 61 Pg ppm−1 and γL = −27. 5 Pg °C−1, are 34 and 53 % less than the averages of CMIP5 models, although the CMIP5 version of JSBACH simulated βL and γL, which are 59 and 42 % higher than multi-model average. These changes are primarily due to the new decomposition model, indicating the importance of soil organic matter decomposition for land carbon feedbacks.
Issue Date: 22-May-2017
Date of Acceptance: 14-Apr-2017
URI: http://hdl.handle.net/10044/1/54662
DOI: https://dx.doi.org/10.5194/gmd-10-2009-2017
ISSN: 1991-959X
Publisher: Copernicus Publications
Start Page: 2009
End Page: 2030
Journal / Book Title: Geoscientific Model Development
Volume: 10
Issue: 5
Copyright Statement: © Author(s) 2017. CC Attribution 3.0 License.
Sponsor/Funder: AXA Research Fund
Funder's Grant Number: AXA Chair Programme in Biosphere and Climate Impacts
Keywords: Science & Technology
Physical Sciences
Geosciences, Multidisciplinary
Geology
EARTH SYSTEM MODELS
DYNAMIC VEGETATION MODEL
SOIL ORGANIC-MATTER
TERRESTRIAL BIOSPHERE
PERMAFROST CARBON
CLIMATE-CHANGE
ECOSYSTEM RESPONSES
DECOMPOSITION RATES
GLOBAL PATTERNS
CYCLE FEEDBACK
04 Earth Sciences
Publication Status: Published
Appears in Collections:Department of Life Sciences
Faculty of Natural Sciences