Including stable carbon isotopes to evaluate the dynamics of soil carbon in the land-surface model ORCHIDEE
Camino Serrano, Marta (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Tifafi, Marwa (Laboratoire des Sciences du Climat et de l'Environnement)
Balesdent, Jérôme (Institut de recherche pour le développement (Marsella, França))
Hatté, Christine (Laboratoire des Sciences du Climat et de l'Environnement)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Cornu, Sophie (Institut de recherche pour le développement (Marsella, França))
Guenet, Bertrand (Laboratoire des Sciences du Climat et de l'Environnement)

Data:	2019
Resum:	Soil organic carbon (SOC) is a crucial component of the terrestrial carbon cycle and its turnover time in models is a key source of uncertainty. Studies have highlighted the utility of δ¹³C measurements for benchmarking SOC turnover in global models. We used ¹³C as a tracer within a vertically discretized soil module of a land-surface model, Organising Carbon and Hydrology In Dynamic Ecosystems- Soil Organic Matter (ORCHIDEE-SOM). Our new module represents some of the processes that have been hypothesized to lead to a ¹³C enrichment with soil depth as follows: 1) the Suess effect and CO₂ fertilization, 2) the relative ¹³C enrichment of roots compared to leaves, and 3) ¹³C discrimination associated with microbial activity. We tested if the upgraded soil module was able to reproduce the vertical profile of δ¹³C within the soil column at two temperate sites and the short-term change in the isotopic signal of soil after a shift in C3/C4 vegetation. We ran the model over Europe to test its performance at larger scale. The model was able to simulate a shift in the isotopic signal due to short-term changes in vegetation cover from C3 to C4; however, it was not able to reproduce the overall vertical profile in soil δ¹³C, which arises as a combination of short and long-term processes. At the European scale, the model ably reproduced soil CO₂ fluxes and total SOC stock. These findings stress the importance of the long-term history of land cover for simulating vertical profiles of δ¹³C. This new soil module is an emerging tool for the diagnosis and improvement of global SOC models.
Ajuts:	European Commission 641816 European Commission 610028
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Soil organic carbon ; Stable isotopes ; Land surface model
Publicat a:	Journal of Advances in Modeling Earth Systems, Vol. 11, issue 11 (Nov. 2019) , p. 3650-3669, ISSN 1942-2466

DOI: 10.1029/2018MS001392
PMID: 32025279

20 p, 6.8 MB

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