Ecological dynamics, resilience and sustainability

This article describes a simple generic system dynamics model of resource dependency in ecosystems to explore the potential range of behaviours that can arise purely due to system structure. The model produces a small number of behaviours that replicate the observed real-world behaviour of ecosystems but does not produce the less plausible outcomes produced in simpler predator–prey models (e.g. Lotka Volterra) such as exponential growth or exploding oscillations. The more limited range of behaviours is attributed to the inclusion in the model of species dependence on abiotic resource flows. The simulations explore the response of systems in equilibrium to various types of ‘shock’ and the outcomes are used to reflect on the concepts of resilience and sustainability. The results challenge the normative understanding of these terms and their relationship to each other. The results also reinforce the notion that shocks to the abiotic system flows at the foundation of all ecosystems present the greatest threat to ‘resilience’ as they affect all trophic levels.