关键词: 常收获率； 常投放率； 等倾线； 平衡点； 闭轨

Abstract:

A preypredator model with constant investment rate and dense restriction for prey and constant harvesting rate for predator under Holling-Ⅳ functional response was studied. The existence of the positive equilibrium point was discussed by using isoclines shape, and the condition for the existence and the stability of the equilibrium point were analysed. Finally, the nonexistence of the closed orbit was proven by Dulac function.

Key words: constant harvesting rate, constant investment rate, isoclines, equilibrium point, closedorbit