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- Title
Importance of crop varieties and management practices: evaluation of a process-based model for simulating CO<sub>2</sub> and H<sub>2</sub>O fluxes at five European maize (Zea mays L.) sites.
- Authors
Li, L.; Vuichard, N.; Viovy, N.; Ciais, P.; Ceschia, E.; Jans, W.; Wattenbach, M.; Béziat, P.; Gruenwald, T.; Lehuger, S.; Bernhofer, C.
- Abstract
Crop varieties and management practices such as planting and harvest dates, irrigation, and fertilization have important effects on the water and carbon fluxes over croplands, and lack or inaccuracy of this information may cause large uncertainties in hydraulic and carbon modeling. Yet the magnitude of uncertainties has not been investigated in detail. This paper provides a comprehensive assessment of the performances of a process-based ecosystem model called ORCHIDEE-STICS (a coupled model between generic ecosystem model ORCHIDEE and the crop growth model STICS), against eddy-covariance observations of CO2 and H2O fluxes at five European maize cultivation sites. The results show that ORCHIDEE-STICS has a good potential to simulate energy, water vapor and carbon dioxide fluxes from maize croplands on a daily basis. The model explains 23-75% of the observed daily net ecosystem exchange (NEE) variance at five sites, and 26-79% of the latent heat flux (LE) variance. Similarly, 34-83% of the variance in observed gross primary productivity (GPP) is accounted for by the model. However, only 3-81% of the variance of observed terrestrial ecosystem respiration (TER) is explained. Therefore, simulating TER is shown to be much more difficult than GPP. We conclude that structural deficiencies of the model in the determination of LAI and TER are the main sources of errors in simulating carbon dioxide and water vapor fluxes. A group of sensitivity analyses, by setting different crop variety, nitrogen fertilization, irrigation, and planting date, indicate that any of these factors is able to cause more than 15% change in simulated NEE although the response of these fluxes to management parameters is site-dependent. Varying management practice in the model is shown to affect not only the daily values of NEE and LE, but also the total seasonal cumulative values, and therefore the annual carbon and water budgets. However, LE is found to be less sensitive to management practices than NEE. Multi-site evaluation of the model and sensitivity analysis with respect to management practices performed in this research provide important insights on the model errors for estimating carbon and water vapor fluxes over European croplands.
- Subjects
CULTIVARS; CROP management; CARBON dioxide; WATER; HEAT flux; CORN; FARMS; BIOTIC communities
- Publication
Biogeosciences Discussions, 2011, Vol 8, Issue 2, p2913
- ISSN
1810-6277
- Publication type
Article
- DOI
10.5194/bgd-8-2913-2011