Theory 14/Hysteresis & Memory/Kelp forests
Kelp Forests Have Two States
The claim
Kelp forests exist in two stable states, and the return from urchin barrens requires a larger reduction in grazing than the increase that caused the shift.
01Mechanism
Barrens persist because urchins suppress recruitment; kelp recovers only when grazing falls far enough for a cohort to escape.
02Prediction
Recovery should require lower urchin density than collapse did.
03Refutation
Symmetric, gradual transition would remove the bistability.