Regime Shifts in Grazing Ecosystems with Internal and External Noise Disturbances
Regime shifts in ecosystems can cause degradation and severe economic losses,hence it is critical to discuss how steady-state shifts are influenced by stochastic factors.In this paper,We investigate the phenomenon of regime shifts in the grazing model under the combined effect of internal Gaussian noise and external Lévy noise.Firstly,we show the deterministic equations of the grazing model in detail,then Lévy noise is generated by Janicki-Weron algorithm,the grazing ecosystem is obtained by using fourth-order Runge-Kutta method.Finally,we analyze the influence of the internal and external noise parameters on the regime shifts separately based on steady-state probability densities(SPD).It is found that both Gaussian noise and Lévy noise can cause the regime shifts phenomenon but with opposite effects.The increase in Gaussian noise intensity enhances the likelihood of regime shifts from high vegetation state to the desert state.While the increase in Lévy noise intensity,stability index and skewness parameter enhances the likelihood of regime shifts from the desert state to the high vegetation state.
grazing systemgaussian white noiseLévy noisesteady-state probability densitiesregime shifts
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