Analysis Of Disturbance Propagation In Ecological Network Based On Infectious Disease Model

Disturbance is inevitable in nature.Ecological disturbance caused by natural and human factors has always threatened the stability of ecosystem.Therefore,researching the propagation dynamics of disturbance,understanding and predicting the propagation strength and scope of disturbance,and taking corresponding measures to prevent or control the propagation of disturbance are of great significance to maintain the stability of ecosystem.Based on the idea of infectious disease model and complex network theory,thesis regards the species in the ecosystem as the network node and the predator-prey relationship between the species as the edge of the network,and constructs a complex ecological network based on the actual ecosystem.At the same time,the disturbance causing the instability of species state is regarded as an infectious disease,and the cascade reaction process between species caused by disturbance is regarded as the propagation of disturbance on the ecological network.Thesis established the interference propagation dynamic model of ecological network,and dynamically analyzed and simulated the model.The research work of thesis mainly includes the following aspects:Firstly,based on the infectious disease model with birth and death,thesis constructs an ecological network disturbance propagation model with species emigrate and immigration,and focuses on the global dynamics of the model.Thesis calculated the basic reproduction number and equilibrium point,gave the threshold condition to judge whether the disturbance can break out,and then proved the global stability of undisturbed equilibrium point and local disturbance equilibrium point.Then,considering the change of basic reproduction number under different species protection strategies,the optimal protection strategy is found to suppress the propagation of disturbance,and the simulation of actual ecological network is given to explore the influence of disturbance related parameters on disturbance propagation.Secondly,in order to study the influence of quarantine measures on disturbance propagation,thesis proposed a disturbance propagation model of ecological network with quarantine term,calculated the basic reproduction number and equilibrium point,and carried out the global dynamic analysis and Simulation of the equilibrium point of the model.By comparing the changes of basic reproduction number before and after quarantine measures,it is found that the addition of quarantine state will reduce the basic reproduction number and reduce the average propagation capacity of disturbance,indicating that quarantine measures can effectively inhibit the propagation of disturbance.Finally,considering the structural changes and dynamic evolution of ecological network caused by species migration and immigration of ecosystem,thesis constructed a disturbance propagation model on dynamic ecological network.The basic properties of the model are analyzed and the basic reproduction number is obtained.At the same time,it is proved that when the basic reproduction number is less than 1,the undisturbed equilibrium point is globally attractive.