Modeling Carbon and Water Fluxes of Managed Grasslands: Comparing Flux Variability and Net Carbon Budgets between Grazed and Mowed Systems

The CenW ecosystem model simulates carbon, water, and nitrogen cycles following ecophysiological processes and management practices on a daily basis. We tested and evaluated the model using five years eddy covariance measurements from two adjacent but differently managed grasslands in France. The da...

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Bibliographic Details
Published in:Agronomy (Basel) 2019-04, Vol.9 (4), p.183
Main Authors: Puche, Nicolas, Senapati, Nimai, Flechard, Christophe R., Klumpp, Katia, Kirschbaum, Miko U.F., Chabbi, Abad
Format: Article
Language:English
Subjects:
Animals
Biomass
Calibration
Carbon cycle
carbon cycling
Carbon dioxide
CenW model
Climate change
Covariance
Dairy cattle
Ecosystem models
Ecosystems
eddy covariance
Exports
Fluxes
grassland
Grasslands
Grazing
Life Sciences
Mowing
Pasture
Respiration
Vortices
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Summary:The CenW ecosystem model simulates carbon, water, and nitrogen cycles following ecophysiological processes and management practices on a daily basis. We tested and evaluated the model using five years eddy covariance measurements from two adjacent but differently managed grasslands in France. The data were used to independently parameterize CenW for the two grassland sites. Very good agreements, i.e., high model efficiencies and correlations, between observed and modeled fluxes were achieved. We showed that the CenW model captured day-to-day, seasonal, and interannual variability observed in measured CO2 and water fluxes. We also showed that following typical management practices (i.e., mowing and grazing), carbon gain was severely curtailed through a sharp and severe reduction in photosynthesizing biomass. We also identified large model/data discrepancies for carbon fluxes during grazing events caused by the noncapture by the eddy covariance system of large respiratory losses of C from dairy cows when they were present in the paddocks. The missing component of grazing animal respiration in the net carbon budget of the grazed grassland can be quantitatively important and can turn sites from being C sinks to being neutral or C sources. It means that extra care is needed in the processing of eddy covariance data from grazed pastures to correctly calculate their annual CO2 balances and carbon budgets.
ISSN:2073-4395
2073-4395
DOI:10.3390/agronomy9040183