Growing A Plant CompositeModel#
Start with Modify Plant Structure for a runnable example of adding and removing leaves, or changing which object they belong to. This page explains how to connect those operations to a growth model and a carbon budget.
Connect organ creation to a resource budget#
Store the plant's carbon reserves on the plant object and each leaf's carbon production on that leaf. Many(scale=:Leaf, within=Subtree()) lets the plant collect production from its own leaves. Before adding production to reserves, check what it represents: a rate, an amount produced during one interval, or a total accumulated since the start of the simulation. For an accumulated total, add only the increase since the last update. Adding the full total at every step would count the same carbon repeatedly.
The growth model's run! function then follows this sequence:
Read the available carbon and check whether the plant is ready to grow.
If so, create the new organ's status with initial area, mass, and any other values its models need.
Subtract the construction cost once. Add the organ to the simulation with a unique identity and the correct parent object.
Check the carbon balance: the remaining reserves, the carbon in the new organ, and any carbon spent on respiration must add up to the amount available before growth.
Use register_object! if your model has already created an Object with all its initial values. If you represent the plant with a MultiScaleTreeGraph (MTG), use add_organ! to create its MTG node, status, and simulation object together. Your growth model must still decide when an organ appears, what it costs, and how carbon is converted to dry matter.
Know when a newborn can run#
When a model adds, removes, or reparents an organ, PlantSimEngine updates which objects each model runs on and where their inputs come from after that application finishes. A new leaf can run models scheduled later in the same timestep. Models that already ran are not repeated. If the new leaf needs one of those earlier calculations immediately, the model creating it must declare an Initializer and call run_initializer!.
If you change the plant structure between step! calls, these connections are updated before the next step. Neither case automatically undoes changes to the plant's values if something goes wrong.
After creating an organ, check its parent, initial values, first saved result, and the plant's carbon budget. Use the working example in Modify Plant Structure to inspect the objects, then continue with Adding Roots And Water for a small resource-accounting example and Debugging Growth And Resource Ordering when execution order is unclear.
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