NetLogo User Community Models

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## WHAT IS IT?

The model simulates the interdependence of trees and myzel in forests.

## HOW IT WORKS

Trees are modeled as trutles, the ground containing the myzel as patches. Trees will do photosynthesis. The amount of energy they can generate is determined by size and the size of trees in the neighbourhood. A part of excess energy can be destributed to myzel and other trees via the myzel network. If a tree can't get enough energy from photosynthesis, it can try to use energy stored in the myzel network.

## HOW TO USE IT

Setup initializes the forest, 10 trees are generated. Loop runs the simulation continuously, step does only one step. Energyneed defines the base amount of energy that the trees will need. The actual need of individual trees is influenced by this value, its size and a random factor. Glogalenergy defines the energy from the sun, i.e. the max amount of energy that can be absorbed in a time period. Mycelrate defines the ratio of energy that can be destributed via the myzel network. Finally, probplnt defines the probability for new trees.

## THINGS TO NOTICE

Trees will grow in size, the amount of myzel is coded into the color of the patch, dark yellow patches hold more myzel, white none.

## THINGS TO TRY

Find configurations where the forest can hardly survive. This will lead to interesting growth dynamics.

## EXTENDING THE MODEL

Develop a more detailed model for the tree-myzel interaction. Add a communication network.

## CREDITS AND REFERENCES

Background info: https://en.wikipedia.org/wiki/Mycorrhizal_network