Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Discussion papers
https://doi.org/10.5194/bg-2018-308
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2018-308
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 18 Jul 2018

Research article | 18 Jul 2018

Review status
This discussion paper is a preprint. It has been under review for the journal Biogeosciences (BG). The revised manuscript was not accepted.

The importance of tree demography and root water uptake for modelling the carbon and water cycles of Amazonia

Emilie Joetzjer1,2, Fabienne Maignan1, Jérôme Chave2, Daniel Goll1, Ben Poulter3, Jonathan Barichivich1,4, Isabelle Maréchaux2,5, Sebastiaan Luyssaert1,6, Matthieu Guimberteau1,7, Kim Naudts1,8, Damien Bonal9, and Philippe Ciais1 Emilie Joetzjer et al.
  • 1Laboratoire des Sciences du Climat et de l’Environnement, LSCE-IPSL (CEA-CNRS-UVSQ), 91190 Gif-sur-Yvette, France
  • 2Laboratoire Evolution et Diversité Biologique, UMR 5174, Université Paul Sabatier, CNRS, IRD, 31400 Toulouse, France
  • 3NASA Goddard Space Flight Center, Biospheric Sciences Laboratory, Greenbelt, MD, USA
  • 4Instituto de Conservación, Biodiversidad y Territorio, Universidad Austral de Chile, Valdivia, Chile, and Center for Climate and Resilience Research, Santiago, Chile
  • 5AMAP, Université de Montpellier, IRD, CIRAD, CNRS, INRA, 34000 Montpellier, France
  • 6Vrije Universiteit Amsterdam, Faculty of Science, 1081 HV, The Netherlands
  • 7UMR 7619 METIS, Sorbonne Universités, UPMC, CNRS, EPHE, 4 place Jussieu, 75005 Paris, France
  • 8Max Planck Institute for Meteorology, Bundesstraβe. 53, 20146 Hamburg, Germany
  • 9Université de Lorraine, AgroParisTech, INRA, UMR Silva, 54000 Nancy, France

Abstract. Amazonian forest plays a crucial role in regulating the carbon and water cycles in the global climate system. However, the representation of biogeochemical fluxes and forest structure in dynamic global vegetation models (DGVMs) remains challenging. This situation has considerable implications for modelling the state and dynamics of Amazonian forest. To address these limitations, we present an adaptation of the ORCHIDEE-CAN DGVM, a second-generation DGVM that explicitly models tree demography and canopy structure with an allometry-based carbon allocation scheme and accounts for hydraulic architecture in the soil-stem-leaf continuum. We use two versions of this DGVM: the first one (CAN) includes a new parameterization for Amazonian forest; the second one (CAN-RS) additionally includes a mechanistic root water uptake module, which models the hydraulic resistance of the water transfer from soil pores to roots. We compared the results with the simulation output of the big-leaf standard version of the ORCHIDEE DGVM (TRUNK) and with observations of turbulent energy and CO2 fluxes at flux tower locations, of carbon stocks and stand density at inventory plots and observation-based models of photosynthesis (GPP) and evapotranspiration (LE) across the Amazon basin. CAN-RS reproduced observed carbon and water fluxes and carbon stocks as well as TRUNK across Amazonia, both at local and at regional scales. In CAN-RS, water uptake by tree roots in the deepest soil layers during the dry season significantly improved the modelling of GPP and LE seasonal cycles, especially over the Guianan and Brazilian Shields. These results imply that explicit coupling of the water and carbon cycles improves the representation of biogeochemical cycles in Amazonia and their spatial variability. Representing the variation in the ecological functioning of Amazonia should be the next step to improve the performance and predictive ability of new generation DGVMs.

Emilie Joetzjer et al.
Interactive discussion
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Interactive discussion
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Emilie Joetzjer et al.
Emilie Joetzjer et al.
Viewed  
Total article views: 410 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
274 132 4 410 29 7 4
  • HTML: 274
  • PDF: 132
  • XML: 4
  • Total: 410
  • Supplement: 29
  • BibTeX: 7
  • EndNote: 4
Views and downloads (calculated since 18 Jul 2018)
Cumulative views and downloads (calculated since 18 Jul 2018)
Viewed (geographical distribution)  
Total article views: 402 (including HTML, PDF, and XML) Thereof 401 with geography defined and 1 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited  
Saved  
No saved metrics found.
Discussed  
Latest update: 18 Jun 2019
Publications Copernicus
Download
Short summary
This study explores the relative contributions of tree demographic, canopy structure and hydraulic processes on the Amazonian carbon and water cycles using large-scale process-based model. Our results imply that explicit coupling of the water and carbon cycles improves the representation of biogeochemical cycles and their spatial variability. Representing the variation in the ecological functioning of Amazonia should be the next step to improve the performance and predictive ability of models.
This study explores the relative contributions of tree demographic, canopy structure and...
Citation