Where n is the total number of individuals in the population, t is the time, r is the population growth potential index, and k is the maximum environmental capacity.
When a species enters a new ecosystem, its number will change. Assuming that the initial number of species is less than the maximum capacity of the environment, this number will increase. There are two growth modes: 1 J growth. If the species has no natural enemies in this ecosystem and has sufficient food space and other resources (ideal environment), the growth function is N(t) = n (p t). Where t is time and p is annual growth rate (greater than 1). The image looks like a j-shape. 2 S growth. If species have natural enemies in this ecosystem, food space and other resources are insufficient (non-ideal environment), the growth function satisfies logistic equation. The image looks like an S-shape. This equation is the best mathematical model to describe the law of population growth under the condition of limited resources.