Blar i forfatter "Kristensen, Ørjan"

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    • Compensatory and overcompensatory dynamics in prey–predator systems exposed to harvest 

      Wikan, Arild; Kristensen, Ørjan (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-11)
      Density dependent prey–predator systems under the impact of harvest are considered. The recruitment functions for both the prey and predator belong to the Deriso–Schnute family which allow us to study how the dynamical behaviour of both populations changes when compensatory density dependence turns overcompensatory. Depending on the degree of overcompensation, we show in the case of no harvest that ...

    • Nonstationary and Chaotic Dynamics in Age-Structured Population Models 

      Wikan, Arild; Kristensen, Ørjan (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-08-06)
      The dynamics from nonlinear discrete age-structured population models is under consideration. Focus is on bifurcations, as well as nonstationary and chaotic dynamics. We also explore different mechanisms which may lead to periodic phenomena. Some new results are also presented, in particular from models where both fecundity and survival terms contain nonlinear elements.

    • Prey-Predator Interactions in Two and Three Species Population Models 

      Wikan, Arild; Kristensen, Ørjan (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-17)
      Discrete nonlinear two and three species prey-predator models are considered. Focus is on stability and nonstationary behaviour. Regarding the two species model, depending on the fecundity of the predator, we show that the transfer from stability to instability goes through either a supercritical flip or a supercritical Neimark-Sacker bifurcation and moreover that there exist multiple attractors in ...