Stage 1: Modelling the dynamics of a single population

Thu, 28/02/2008 - 17:09 — administrator

Step 1	Add two compartments to the desktop, and rename them rabbits and foxes
Step 2	Draw a flow into the rabbits compartment, and rename it rabbit repro
Step 3	Draw a flow out of the rabbits compartment, and rename it predation
Step 4	Draw an influence arrow from: the rabbits compartment to the rabbit repro flow; the rabbits compartment to the predation flow; the foxes compartment to the predation flow; Your model diagram should now look like this:
Step 5	Enter the following expression for the rabbit repro flow: 0.5*rabbits
Step 6	Enter the following expression for the predation flow: 0.01rabbitsfoxes
Step 7	Set the initial value for the rabbits compartment to 5000
Step 8	Set the initial value for the foxes compartment to 45
Step 9	“Build” the model.
Step 10	Change the Run Control settings: Set Execute for to 50 Set Time step #1 to 0.1
Step 11	Set up a plotter display for the rabbits compartment.
Step 12	Run the model Note that the rabbit population grows exponentially — there is nothing to hold it in check.