Convergence of socio-ecological dynamics in disparate ecological systems under strong coupling to human social systems

摘要

It is widely recognized that coupled socio-ecological dynamics can be qualitatively different from the dynamics of social or ecological systems in isolation from one another. The influence of the type of ecological dynamics on the dynamics of the larger socio-ecological system is less well studied, however. Here, we carry out such a comparison using a mathematical model of a common pool resource problem. A population must make decisions about harvesting a renewable resource. Individuals may either be cooperators, who harvest at a sustainable level, or defectors, who overharvest. Cooperators punish defectors through social ostracism. Individuals can switch strategies according to the costs and benefits of harvesting and the strength of social ostracism. These mechanisms are represented by a differential equation for social dynamics, which is coupled to three different types of resource dynamics: logistic growth, constant inflow, and threshold growth. We find that when human influence is sufficiently weak, the form of resource dynamics leaves a strong imprint on the socio-ecological dynamics, and human social dynamics are qualitatively very different from resource dynamics. However, stronger human influence introduces a broad intermediate parameter regime where dynamical patterns converge to a common type: the three types of ecological systems exhibit similar dynamics, but also, social and ecological dynamics mirror one another. This regime of strong human influence includes generation of stable limit cycles at high rates of social learning. Such oscillations are a consequence of stronger coupling and are reminiscent of synchrony in other fields, such as the classic problem of coupled oscillators. Socio-ecological convergence has implications for how we understand and manage complex socio-ecological systems. In an era of growing human influence on ecological systems, further empirical and theoretical work is required to determine whether socio-ecological convergence is present in real systems.