Competition between injunctive social norms and conservation priorities give rise to complex dynamics in a model of forest growth and opinion dynamics
Human systems and environmental systems are often treated as existing in isolation from one another, whereas in fact they are often two parts of a single, coupled human-environment system. Developing theoretical models of coupled human-environment systems is a continuing area of re- search, although relatively few of these models are based on differential equations. Here we develop a simple differential equation coupled human-environment system model of coupled forest growth dynamics and conservationist opinion dynamics in a human population. The model assumes logistic growth and harvesting in the forest. Opinion spread in the human population is based the interplay between conservation values stimulated by forest rarity, and injunctive social norms that tend to support population conformity. We find that injunctive social norms drive the system to the boundaries of phase space, whereas rarity-based conservation priorities drive the system to the interior. The result is complex dynamics including limit cycles and alternative stable states that do not occur if injunctive social norms are absent. We also find that increasing the inherent perceived value of forests is the best way to boost and stabilize forest cover while also boosting conservationist opinion in the population. We conclude that simple models can provide insights and suggest pat- terns that might be harder to see with complicated, high-dimensional models, and therefore should be pursued more often in research on coupled human-environment systems.