Cellular Automaton Model of Pine Savanna Dynamics in Response to Fire and Hurricanes

grass-pine fire interaction (GPI)

1

lightning intensity (LI)

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hurricane probability (HurrP)

1

Savanna state as a function of hurricanes, fire, and an interaction between fire and vegetation on burn probability. Annual probability of a hurricane varies across the set {0, 0.05, 0.1, 0.2, 1}, which corresponds to a return period of {∞, 20, 10, 5, 1} years. Lightning strike intensity on the landscape is distributed as a Poisson random variable with lambda parameter equal to lightning strike intensity multiplied by the number of cells in the landscape. Lightning strike intensity varies across the set {0, 0.0004, 0.004, 0.04, 0.4}, which corresponds to an expectation of {0, 1, 10, 100, 1000} lightning strikes in a

50×50

cell landscape. The grass-pine interaction term varies across the set {1, 100, 10000, 100000, 1000000}, which corresponds to a maximum odds ratio of the cell burning of {1, 100, 10 000, 100 000, 1 000 000} when the neighborhood of adjacent cells includes four cells of grass and pine.

Color Legend: Grass cells are brown, juvenile pine cells are light green, adult pine cells are green, juvenile hardwood tree cells are light blue, and adult hardwood tree cells are blue.