Models of ecological communities: genericity and criticality

Theoretical models are central to how we think of ecosystems, and yet in many aspects remain poorly understood. We identify a small number of parameters that are sufficient to predict the large-scale properties of a wide variety ecological-community models. These parameters thus play a role similar to temperature and pressure in thermodynamics. We go on to study the generic model that emerges, and describe its phases, including a critical phase where all states are marginally stable.