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@INPROCEEDINGS{Dombrowski:905605,
      author       = {Dombrowski, Olga and Brogi, Cosimo and Hendricks-Franssen,
                      Harrie-Jan and Zanotelli, Damiano and Bogena, Heye},
      title        = {{CLM}-{A}pple: {A} {P}erennial {P}lant {F}unctional {T}ype
                      for the {C}ommunity {L}and {M}odel {CLM}5},
      reportid     = {FZJ-2022-00837},
      year         = {2021},
      abstract     = {Orchards and other perennial crops represent one percent of
                      the total global agricultural area. A significant portion is
                      found in Mediterranean Europe covering 16 $\%$ of the total
                      agricultural land. Apples are one of the most popular and
                      valuable fruits and make up one third of all European
                      orchards, covering more than 463’000 ha. In contrast to
                      annual crops, perennial tree crops can be productive for
                      several decades before rotation is needed. Moreover, the
                      standing biomass of such cultivation serves as carbon
                      storage and thus influences the carbon cycle in a different
                      way than annual crops. However, perennial tree crops are
                      rarely considered in the land components of earth system
                      models. This creates an important gap in the representation
                      of biogeophysical and biogeochemical processes that are a
                      consequence of such agro-ecosystems. In this work we
                      implemented an apple tree crop sub-model named CLM-APPLE
                      that allows the simulation of a new apple plant functional
                      type (PFT) within the existing framework of the Community
                      Land Model version 5 (CLM5). Similarly to the existing
                      deciduous tree PFTs that are available in CLM5, the apple
                      PFT is described by a perennial deciduous phenology with
                      standing woody biomass and annual leaf shedding. During the
                      active growth period, the phenology and the carbon and
                      nitrogen allocation of vegetative and harvestable organs are
                      described by distinct growth phases and are driven by a
                      growing degree day summation. In this new PFT, both the
                      storage pool and the photosynthetic pool contribute to tree
                      growth since, in fruit trees, leaf and shoot development at
                      the beginning of a growing season utilizes carbohydrate
                      reserves and nitrogenous compounds that were accumulated
                      during the previous season. Furthermore, agricultural
                      practices such as transplanting, fertilization, and stem
                      pruning are represented in the new sub-model. New parameters
                      were introduced, calibrated, and then validated with
                      extensive field measurements from an apple-growing region in
                      the Adige River valley (Italy). Monthly biomass components
                      and leaf area index (LAI), measured directly and
                      independently over six representative plots, were used for
                      model calibration. Additionally, multiple years of
                      continuous soil respiration measurements, eddy covariance
                      measurements, and yield data were used for model calibration
                      and validation. Simulated patterns in seasonal biomass
                      allocation and LAI showed good agreement with the
                      observations. Similarly, the simulated average yield between
                      2010 and 2015 was within 5 $\%$ of the observed yield.
                      However, the observed inter annual variability was not well
                      represented in the simulations. Overall, the model
                      validation using eddy covariance data demonstrated the
                      ability of the model to represent the seasonal dynamics and
                      magnitudes of ecosystem fluxes at the orchard level. Despite
                      these encouraging results, an accurate representation of
                      inter-annual yield dynamics and seasonal fluctuations of
                      fluxes at the orchard-scale remains challenging, suggesting
                      the existence of processes that are not yet implemented in
                      the model. Nonetheless, the newly developed sub-model
                      CLM-APPLE allows the exploration of the carbon allocation
                      dynamics and ecosystem fluxes in orchards as well as their
                      effects on the terrestrial biogeochemical cycle.},
      month         = {Oct},
      date          = {2021-10-05},
      organization  = {First Ozcar-Tereno International
                       Conference, Strasbourg (France), 5 Oct
                       2021 - 7 Oct 2021},
      subtyp        = {Other},
      cin          = {IBG-3},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {2173 - Agro-biogeosystems: controls, feedbacks and impact
                      (POF4-217) / ATLAS - Agricultural Interoperability and
                      Analysis System (857125)},
      pid          = {G:(DE-HGF)POF4-2173 / G:(EU-Grant)857125},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/905605},
}