This is a model representing a rainforest ecosystem. There are four tropic levels. The primary producers are: grass and berries. The primary consumer is sloths. The secondary consumers are snakes. The third and final levels of consumers (in this model) are jaguars and eagles. There are two third level consumers because they are the main predators, and I wanted to see how having two predators would affect an ecosystem. The limiting factor in this model is the water - it doesn't increase, so it doesn't decrease either, which isn't how it works in reality, but the most effective so that the water isn't too much of an issue. The population graph on the interface shows the birth and death rates. Energy transfer is also shown - the animals gain energy when they eat something. They lose energy when they give birth, and they have to be at 0 energy to die. The probability portion of the model is in the birth and death - there's a certain chance that organisms will give birth, since often times, the babies don't get a chance to live properly or die earlier. When an animal is being eaten, there is a 75% percent chance, since many animals do get away without being eaten.
Grass and berries use the water to grow. Then the sloths, snakes, jaguars, and eagles all eat the grass and berries. (Water too). The snakes are eaten by the jaguars and eagles. The jaguars and eagles, not to mention, eat all the organisms in the tropic levels below.
Limitations: One of the limitations in this model is that it doesn't include evolution. Evolution can change species so that they can better survive, but this model doesn't allow them to do that. This may have been able to be represented with a code that had something be done after a certain point of time. However, I could not figure out a code to make this work, so I decided to represent a more basic system. Secondly, there are many other animals and organisms in an ecosystem, but I couldn’t include them all because of how small the screen was. One of the biggest strengths in this is that the numbers can be changed to find the perfect number/balance of animals, and also to experiment with each of the organisms (like what taking away the berries or sloths would do to the ecosystem). This way, it’s easier to see how big of an effect there is on the ecosystem by each organism. Because there is no evolution/way to change the code of any organisms in the middle, the model always ends with Jaguars taking over at around 200, sometimes a little earlier. Another glitch/limitation: the grass always dies at first even though the code is for it to not die (for almost all the organisms)