These NetLogo computational models allow users to change the code and observe the effect of those changes.That is one very important feature of these Emergent Systems Microworlds, that you can play with those by changing the parameters such as 'density' or by changing the code as well.
Now try to read the code. Write a line in the code below and explain how it affects the way the model would behave.
set initial-trees count patches with [pcolor = green]
This line above, sets a value for a variable 'initial-tree' by counting the patches that have pcolor (patch-color). This line is written in NetLogo language that the NetLogo compiler understands.
NetLogo language is designed to be easy to understand for humans. Pick another line in the code and explain what it could mean.