文摘
To understand the effect of the probability of a predator catching prey, Pcatch, on the stability of the predatorx2013;prey system, a spatially explicit lattice model consisting of predators, prey, and grass was constructed. The predators and prey randomly move on the lattice space, and the grass grows according to its growth probability. When a predator encounters prey, the predator eats the prey in accordance with the probability Pcatch. When a prey encounters grass, the prey eats the grass. The predator and prey give birth to offspring according to a birth probability after eating prey or grass, respectively. When a predator or prey is initially introduced or newly born, its health state is set at a high given value. This health state decreases by one with every time step. When the state of an animal decreases to less than zero, the individual dies and is removed from the system. Population densities for predator and prey fluctuated significantly according to Pcatch. System stability was characterized by the standard deviation of the fluctuation. The simulation results showed that for predators increased with an increase of Pcatch; for prey reached a maximum at Pcatch = 0.4; and for grass fluctuated little regardless of Pcatch. These results were due to the tradeoff between Pcatch and the predatorx2013;prey encounter rate, which represents the degree of interaction between predator and prey and the average population density, respectively.