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Grain Yield Observations Constrain Cropland CO 2 Fluxes Over Europe
Author(s) -
Combe M.,
de Wit A. J. W.,
VilàGuerau de Arellano J.,
van der Molen M. K.,
Magliulo V.,
Peters W.
Publication year - 2017
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2017jg003937
Subject(s) - biosphere , environmental science , carbon cycle , european union , carbon fibers , yield (engineering) , atmospheric sciences , crop yield , agronomy , ecosystem , mathematics , ecology , geology , biology , economic policy , materials science , algorithm , composite number , metallurgy , business
Carbon exchange over croplands plays an important role in the European carbon cycle over daily to seasonal time scales. A better description of this exchange in terrestrial biosphere models—most of which currently treat crops as unmanaged grasslands—is needed to improve atmospheric CO 2 simulations. In the framework we present here, we model gross European cropland CO 2 fluxes with a crop growth model constrained by grain yield observations. Our approach follows a two‐step procedure. In the first step, we calculate day‐to‐day crop carbon fluxes and pools with the WOrld FOod STudies (WOFOST) model. A scaling factor of crop growth is optimized regionally by minimizing the final grain carbon pool difference to crop yield observations from the Statistical Office of the European Union. In a second step, we re‐run our WOFOST model for the full European 25 × 25 km gridded domain using the optimized scaling factors. We combine our optimized crop CO 2 fluxes with a simple soil respiration model to obtain the net cropland CO 2 exchange. We assess our model's ability to represent cropland CO 2 exchange using 40 years of observations at seven European FluxNet sites and compare it with carbon fluxes produced by a typical terrestrial biosphere model. We conclude that our new model framework provides a more realistic and strongly observation‐driven estimate of carbon exchange over European croplands. Its products will be made available to the scientific community through the ICOS Carbon Portal and serve as a new cropland component in the CarbonTracker Europe inverse model.