3.0 Representing Ecological Models with Discrete Event Simulation

Representing Ecosystems

We divide ecosystems into two categories, the biological members and the physical environment. The biological members are the fauna and flora of interest in our simulations and the physical environment gives the simulation a geographic context.

For the remainder of this tutorial, we will use the Lyme Disease simulation under development for the EST. This simulation is based on work done by Deelman et al. [DEEL 96]. The objective of the model is to simulate the effectiveness of the Deer Mouse, Paromyscus Maniculatus, as a resevior for the Lyme disease spirochete, Borelia Burgdorfei. P. Maniculatus is infected with the spirochete when bitten by an infected Deer Tick, Ixodes Pacificus. To simulate the interactions we simulate mouse movements each mouse will remain in a single location for an average of 20 days with an exponential waiting time. When the mouse moves it determines whether the cell is occupied. If it is occupied, the mouse will move the next day. Each time the mouse is forced to move it has a n/5 chance of dying, where n is the number of consecutive days moving.

The subsections of this section will describe more specifically the kinds of details we need to consider when writing a simulation.