Measuring perturbation in a complicated, thermodynamic world

Abstract Our inability to measure perturbation beyond a context- or system-specific manner has been a fundamental bottleneck to the generalisation of a great number of ecological concepts. Here we develop and explore a thermodynamically inspired solution to this problem as developed by Prigogine and colleagues. We empirically and theoretically demonstrate how the ratio of community respiration to community biomass is an index of the distance from a general thermodynamic steady-state. Using this approach, we re-examine some very old ecological questions (e.g. the patterns of size and abundance; the spatio–temporal complexity of ecological interactions) and other more recent questions (e.g. the leakiness/efficiency of food webs; the relevance of non-linear interactions and critical behaviour to ecology). We discuss these implications and connections and develop a strong theoretical and physical foundation for the study of ecological change.