This is showing the population increasing because of birth rates, the birth rates are increase because of good resources which is allowing the population to increase even more then the population levels off because the resources are running out and more competition is immigrating to the ecosystem with the valuable resources.
The elephant population increases in two ways through either reproduction or immigration of other elephants into the ecosystem attracted by the plentiful resources. This pattern continues until consumption surpasses the amount of usable resources. as the resources become more limited total competition between elephants increases. Elephant populations decrease in two ways death which cause them leave the system and ,emigration occurs when you have limited resources and increase competition, the elephants who can not compete emigrate from the ecosystem into another where resources are available.