The effects of management on population dynamics of plateau pika

Abstract

The plateau pika (Ochotona curzoniae) inhabits the Qinghai/Tibetan Plateau of China. Its role on the grassland ecosystem is not quite understood. Some researchers regard it as a keystone species while others treat it as a pest. At least, the overabundance of plateau pika population accelerates degrading of alpine meadows mainly through their burrowing activity. Therefore, it is necessary to manage pika population. The commonly employed management strategies are lethal control, contraceptive control, and vegetation restoration. To study the control effect, we develop a cellular automata model. In the simulation, we consider three time manners (single control, impulsive control at fixed times and state-dependent impulsive control) and two space manners (uniform control and mosaic control). Not surprisingly, a better control effect can be achieved with a larger killing rate in lethal control, or a larger contraception rate, or a larger degree in grassland restoration. On the other hand, uniform control has distinctly better results than mosaic control. Hence, in practice, uniform control is strongly recommended. With uniform control, some results are summarized as follows. In both lethal control and contraceptive control, the best strategy is to apply state-dependent impulsive control; if control is implemented in the non-growing season then the implementation time makes no difference. However, if control is implemented in the breeding season of pika, in lethal control, the later it is implemented the better is the control effect; while in contraceptive control, the earlier it is implemented the better is the control effect. Compared with lethal control, non-disseminating contraceptive control has a better control result if only one control is implemented; but if controls are implemented too often then lethal control has a better control effect.