Regime shifts in ecological and socio-ecological systems

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Sigdel, Ram
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University of Guelph

Alternative stable states are common in nature, as are regime shifts that take a system from one stable state to an alternative contrasting one. Regime shifts have been explored in social models, ecological models, and coupled socio-ecological models. These models show that regime shifts may be driven either by human factors (such as social norms) or natural factors (such as fire in forest-grassland systems). Our objective is to identify the conditions that give rise to regime shifts in a selection of ecological and socio-ecological models, and to determine which conditions foster regime shifts to sustainable outcomes. For this purpose, we have considered ordinary differential equation models and used both qualitative and quantitative analysis. We conclude that regime shifts are common across ecological and socio-ecological systems and are caused by different drivers, but across all three model systems (two socio-ecological and one ecological), we find that increasing resource growth rates and/or decreasing harvesting rates best generate sustainable outcomes that are far away from tipping points and oscillations. We also find that social norms and threshold-based recruitment functions tend to generate alternative stable states in social and ecological subsystems alike.

regime shifts, ecological systems, socio-ecological systems, differential equation models