A diffusive logistic problem with a free boundary in time-periodic environment: favorable habitat or unfavorable habitat

الأصل · EN

We study the diffusive logistic equation with a free boundary in timeperiodic environment. To understand the effect of the dispersal rate d, the original habitat radius h₀, the spreading capability μ, and the initial density u₀ on the dynamics of the problem, we divide the time-periodic habitat into two cases: favorable habitat and unfavorable habitat. By choosing d, h₀, μ and u₀ as variable parameters, we obtain a spreading-vanishing dichotomy and sharp criteria for the spreading and vanishing in time-periodic environment. We introduce the principal eigenvalue λ₁(d, α, γ, h(t), T) to determine the spreading and vanishing of the invasive species. We prove that if λ₁(d, α, γ, h₀, T)≤ 0, the spreading must happen; while if λ₁(d, α, γ, h₀, T)> 0, the spreading is also possible. Our results show that the species in the favorable habitat can establish itself if the dispersal rate is slow or the occupying habitat is large. In an unfavorable habitat, the species vanishes if the initial density of the species is small, while survive successfully if the initial value is big. Moreover, when spreading occurs, the asymptotic spreading speed of the free boundary is determined.