Properties of dissipative solitons generated in all-normal-dispersion fiber lasers through the gain dispersion effect are numerically studied by using a pulse-tracing technique that considers interaction between gain saturation, gain dispersion, cavity dispersion, fiber Kerr nonlinearity, and cavity boundary conditions. The numerical results qualitatively match with experimental observations and show that the finite gain bandwidth, together with the pump power, determines the properties of the generated dissipative solitons, which further dictates the performance of the pulse compression.