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@ARTICLE{Herbst:889718,
      author       = {Herbst, Michael and Pohlig, Philipp and Graf, Alexander and
                      Weihermüller, Lutz and Schmidt, M. and Vanderborght, Jan
                      and Vereecken, H.},
      title        = {{Q}uantification of water stress induced within-field
                      variability of carbon dioxide fluxes in a sugar beet stand},
      journal      = {Agricultural and forest meteorology},
      volume       = {297},
      issn         = {0168-1923},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier},
      reportid     = {FZJ-2021-00340},
      pages        = {108242 -},
      year         = {2021},
      abstract     = {Net ecosystem exchange of carbon dioxide (NEE) and soil
                      respiration at field scale can exhibit considerable spatial
                      variability linked to the heterogeneity of soil properties
                      and state variables. In this study, we measured NEE with the
                      eddy covariance (EC) method in a sugar beet field
                      characterized by high spatial variability in soil physical
                      properties. We further measured NEE and soil respiration by
                      chambers as well as soil water content and temperature at 18
                      locations within the field.Spatially averaged
                      chamber-measured NEE showed good agreement to the EC-based
                      data. During a dry period high spatial variation of
                      within-field NEE was detected with the chamber method. The
                      coefficient of variation was on average 0.57 during the dry
                      period, with a maximum of 0.72. Based on the depth-specific
                      soil water content measurements the AgroC ecosystem model
                      was inverted for soil hydraulic properties at each of the 18
                      locations, where soil water content was measured. Analyzing
                      the model results revealed that root water uptake stress was
                      the main driver of spatial and temporal variability in crop
                      development and NEE, whereby the soil coarse material
                      fraction (gravel content) and thickness of the layer above a
                      gravel dominated soil layer were identified as the main
                      influencing soil properties.The chamber-measured NEE and the
                      flux footprint analysis showed that particularly during
                      periods of severe root water uptake stress EC-based
                      measurements would be prone to biases. A combination of the
                      footprint model with the AgroC ecosystem model estimated a
                      bias of 14 $\%$ for the dry period and a vegetation period
                      bias of 6 $\%$ in relation to the average CO2 flux.},
      cin          = {IBG-3},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {2173 - Agro-biogeosystems: controls, feedbacks and impact
                      (POF4-217)},
      pid          = {G:(DE-HGF)POF4-2173},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000608676000008},
      doi          = {10.1016/j.agrformet.2020.108242},
      url          = {https://juser.fz-juelich.de/record/889718},
}