Pulse Persistent Pollution Of The Environment In The Population Ecology Model

At present, the problem of the environment pollution becomes very critical, which resultsin negative effect, especially it is harmful to the ecosystems. It has been an important problemfor the ecologist to study all of world. In recent years, many researchers have investigated theeffect of the environment pollution on the ecosystems. In their work, they thought the input ofthe toxicants in the environment is continuous, but in fact, the input of the toxicants is oftenperiodic and well-regulated. This input can be considered as an impulsive effect. In thisdissertation we have described the case by some impulsive differential equation models andgiven some threshold conditions which can keep the populations persistent survival orextinction. In chapter 1, we have introduced the status-quo of the environment pollution and itsharms to the ecosystems in detail. In chapter 2, we have set up a dynamics model which canreflect the toxin change of the organism in an impulsive polluted environment. The resultsshow that under the impulsive effect of the toxicants, the toxin concentration in the organismswill asymptotically tend to a stable periodic solution. In chapter 3, we have proposed apredator-prey system dynamical model in a polluted environment with impulsive toxicantsinput. We have studied the duration of the two populations and given some thresholds oftoxicant input under which they would be weak average persistent. In chapter 4, we haveresearched a predator-prey system with a predator population and two predator populations ina polluted environment with impulsive toxicants input. We also studied the duration of thethree populations and given some thresholds of toxicant input under which they will be weakaverage persistent respectively. In the end of each chapter, there are some numeric simulationresults which indicate the validity of the presented theoretic conclusions.