Ecosystem Dynamics

Core Ontological Distinctions

Resistance (Inertia) is the capacity to withstand a disturbance without changing state (e.g., a mature redwood forest resisting a surface fire, though if destroyed it takes centuries to recover). Resilience is the capacity to recover rapidly after being altered (e.g., a prairie grassland that burns to ash in minutes—low resistance—but regrows from underground roots in weeks—high resilience).

A Pulse Disturbance is a sudden, acute, short-duration event (flash flood, wildfire, storm) after which the stressor stops. A Press Disturbance is a chronic, sustained stressor (continuous sewage discharge, permanent grazing) that prevents return to the original baseline. A Ramp Disturbance steadily increases in intensity over time (prolonged multi-year drought, global warming).

A Threshold (Tipping Point) is the exact point where an ecosystem flips into an alternative stable state. Hysteresis means that simply restoring the environmental condition back to the exact threshold level where the collapse happened will not bring the original ecosystem back—you must push conditions much further back to overcome the self-stabilizing feedbacks of the degraded state.