The figure above shows one of the data-entry screens in the Ecocyb program used by ecology students at Marietta College. Students can change any of the parameters in the boxes, calculate the resulting population sizes, and print out the graph. This program would be used to help answer "real life" type problems.
The figure below shows the graphical output:
In this figure, you can see how the data are plotted. Not visible, however, is the fact that when the computer cursor is on the graph, a readout appears to tell the user the exact x and y coordinates of the point where the cursor is placed. Pretty slick, eh?
This picture shows the results of a predator-prey model. In the red zone, predators increase in number while prey decrease; in the gray zone both predators and prey are decreasing in number; in the blue zone prey increase while predators continue to decrease, and in the green zone both predators and prey increase in numbers. The yellow zone is for unloading only (or is that the white zone?). The same data can be plotted in a more conventional fashion as shown below:
Finally, the figure below shows my implementation of Lovelock's Daisyworld. In this scenario, a planet exposed to the heat of a sun whose temperature is slowly increasing would normally show a temperature increase of its own (red bar & line). Two species of plants grow on the planet, white daisies and black daisies (white and black lines) Their combined numbers are plotted as a gray line. Initially, the black plants, which can warm themselves in the sun, increase in number. They absorb so much light they warm the planet above its normal temperature (green line). As the planet warms, it favors the white plants, which increase in number. They reflect heat, cooling the planet. The black plants and white plants reach an equilibrium which keeps the planet cool long after the sun would have made it inhospitable for life.
Students in the class have an assignment to investigate the stability of the planet by manipulating the variables.
Return to McShaffrey Home Page
Return to About Marietta College
Still Working on This Page 