Quokkas on an Island
This model compares exponential growth vs logistic growth of a Quokka population. Quokka's are a small creature which are native to the Australian continent. This population increases due to addition of joey's that enter the initial quokka population through each quokka mother that gives birth. The loss of numbers is the quokka's leaving the population by death. This whole system keeps the quokka population in equilibrium and can also act as a guide to sustainability, as it allows us to view birth and death rates of a population. We can then work with the numbers of this model to decide how we want to approach this population with sustainability in mind. For example, a high birth rate means we would need to find methods to control the population to create a sustainable environment which is able to maintain this population.
The second version of the model introduces the concept of a Carrying Capacity and uses "logistic" growth formula, which "caps" the population - this is representing resource limitation.