Intermediate Disturbance Hypothesis (Connell 1978):
At low disturbance: competitive exclusion eliminates weaker species — one dominant takes over.
At high disturbance: too many extinctions, communities can't recover, only r-strategists persist.
At intermediate disturbance: competitive exclusion is slowed; colonizers can establish → maximum diversity.
The IDH is debated: meta-analyses show the hump is context-dependent, but the mechanism is well-established.