Perturbation only applies when system parameters and normal state are explicitly defined

Evidence

We feel, therefore, that the term “perturbation” is most useful in three relatively narrow contexts: (a) when the parameters or behaviors that define a system have been explicitly defined, (b) when a given disturbance is known to be new to the system at hand (e.g., some kinds of human disturbances), and (c) when the distur­ bance is under direct experimenter control. In these cases, a “perturbation” is a departure (explicitly defined) from a normal state, behavior, or trajectory (also explicitly defined). It is unlikely that natural ecosystems can be characterized in enough detail to warrant frequent use of “perturbation.” — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 75

Categorization

• DEFINE: Contrasts the narrow, well-defined ‘perturbation’ against the broader, normalcy-free ‘disturbance.’
• SEED: The idea that ‘new to the system’ human disturbances are the clearest perturbations feeds directly into the environmental-justice thread of the landscape course: colonial/industrial changes as genuinely novel forcing functions.