This graph represents how the leopard population has reached its carrying capacity in its environment. Reasons why the leopard population had gotten so big could be the amount of resources they had access to in this time period like the amount of food, water, territory, and little competition.
Two events that could occur and cause population growth and decline could be immigration and emigration. If some of the population decides to leave and find new territory that will leave more resources for the leopards that decide to stay and that could increase the population but with individuals leaving the area in could cause a little bit of a decline but it would stop. But if more leopards start to immigrate back into the previous population resources would start to become scarce as more leopards start to compete for territory and soon the population would start to decline due to the limited resources.
Two other things that determine the size of the population is the amount of births and deaths. If the leopards have access to many resources and no competition from other Savannah predators like lions then the amount of births would increase and the population would increase as well. But if the resources are scarce due to competition from other predators in the area then the number of deaths will increase causing the population to decline.
Examples of density dependent factors for the leopards are competition and other predators. Leopards compete against each other for many things including food and territory and will often get into fights because of it. A specific example for predators would be lions. Lions will often steal food from leopards soon after leopards kill an animal, that is the reason why leopards also drag their prey up a tree to keep it safe.
In the leopards habitat it is not uncommon for a drought or overheating to occur. In the Savannah it is very hot and many heat wave occur causing some animals like the leopard to over heat and die. These heat waves also cause drought limiting water making it hard for the leopard to survive. But leopards are not the only ones, the leopards prey could also not survive due to the drought and no food being available causing the leopards to also run out of food.