Three-level predator–herbivore–plant dynamics with cascade effects
Trophic cascades (Paine 1969) occur when changes at one trophic level ripple through the food web. In Yellowstone, wolf reintroduction (1995) suppressed elk, allowing vegetation to recover — an indirect positive effect across two trophic levels. This 3-species model: dW/dt = −dW + εαWE, dE/dt = rE(1−E/K) − αWE − βEP_benefit... shows how removing the keystone predator triggers cascade collapse.