GreenLab Course
Production - Expansion
Principles
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The GreenLab model refines classic process-based models but is not a process-based model or a functional structural plant model
Functioning: GreenLab vs PbM & FSPM
Computing biomass production
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Photosynthesis is simplified compared to classic PbMs:
In particular, LUE and PAR are not model inputs, an aggregate E(n) parameter standing for environmental conditions is used instead. However, this point can be refined.
Photosynthesis is simplified compared to classical FSPM:
Production is not differentiated in the plant. The Beer Lambert law is applied on the whole plant. For instance, radiation studies at different plant heights, which are classic in FSPM, cannot be operated on the GreenLab model.
Respiration
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Respiration is ignored in the GreenLab model, and poorly studied so far.
However, if respiration is considered as a fixed structural cost, the model will implicitly integrate its effect through the existing parameter to be fitted on measurements.
Maintenance costs could be integrated into the current model without any particular difficulties.
Spatial/structural heterogeneity
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GreenLab assumptions related to the Beer Lambert Law and organ cohorts consider the plant level as a whole.
The finest functional level is defined by the organ cohorts. Variance at this level can be simulated (for instance arising from the stochastic number of organs in cohorts) but not explained.
Thus, if cohorts are explicitly related to structural and geometrical aspects, spatial and structural heterogeneity can be studied. For instance, pruning all axes borne on a given date is easy to model and simulate.
However, geometrical and structural gradients cannot usually be considered. For instance, the case of the effects of mechanics, or pruning at a given height cannot be taken ino account.
Interaction with other models
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As far as external models can be expressed at the lowest GreenLab level, i.e. according to organ cohort indexes with the
growth cycle as a synchronizing scheduler, interactions with other models are possible.
For example, pest attacks, if located according to plant phenology (leaf age, physiological age, etc.) can even be closely integrated as:
- external organ sinks
- biomass production reducers