When a constant finite multiplier exceeds unity, geometric growth compounds abundance at each discrete interval. Early increases may appear modest, but every increment enlarges the base from which the next increment is produced. Plotting population size against time therefore yields a trajectory that bends progressively upward, conventionally called a J-shaped curve. This shape is the discrete-time counterpart of continuous exponential growth. It differs from the sigmoid or S-shaped logistic curve, in which density dependence progressively lowers per-capita growth as abundance approaches carry
Ref:
Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 11