Original definition from Holling (1973, p. 17): “Resilience determines the persistence of relationships within a system and is a measure of the ability of these systems to absorb changes of state variables, driving variables, and parameters, and still persist.” Since then, two concepts have emerged (see Gunderson 2000 for a review): (a) Ecological resilience: The magnitude of the disturbance that a system can experience without undergoing a regime shift, i.e. before it goes into the basin of attraction of another stable state. It corresponds to the size of the basin of attraction in ecosystems with alternative stable states. Ecosystems with low resilience may easily shift into an alternative basin of attraction after a disturbance. (b) Engineering resilience: The time required for a system to return to equilibrium following a perturbation (from Kéfi 2008, Ph.D. Thesis, p. 15).