Forest Fire Model
The Drossel-Schwabl forest fire model. Empty ground grows trees with probability p. Trees catch lightning with probability f. Fire spreads instantly to all connected trees. Click to ignite fires directly.
Empty ⟶ Tree (prob p) Tree ⟶ Fire (prob f) Fire ⟶ Empty (next step)
The Drossel-Schwabl forest fire model (1992) is a cellular automaton with three states: empty, tree, and burning. Each step, empty cells grow trees with probability p; trees can be struck by lightning with probability f; and burning trees spread fire instantly via flood-fill to all connected trees before becoming empty.
The key insight is the ratio p/f. When this ratio is large, fires grow big before they hit a gap. When small, the forest stays sparse and fires are tiny. At intermediate values, the system self-organizes near a critical state with power-law fire size distributions — the hallmark of self-organized criticality.
Click anywhere on the grid to ignite that patch directly.