Fire simulations in the Everglades landscape using parallel programming

Fire can significantly influence vegetation patterns in the Everglades. Unfortunately, fire is a difficult process to experimentally manipulate, especially at a landscape level. An Everglades Landscape fire model (ELFM) was developed using parallel-processing algorithms and transputer-processors to understand fire behavior in Water Conservation Area 2A (WCA 2A) in the Everglades. Fuel characteristics, water depth, wind velocity and direction, rainfall, lightning, and humidity determined the physical state and rate at which fire spreading and spotting occurred in the ELFM. The ELFM simulated fire spread across a heterogeneous landscape using a grid-based system. Parallel processing enabled the model to simulate fire on a large spatial scale with fine resolution (i.e., 1755 times 1634 pixels with 20 times 20 m resolution). The model was designed as a multiprocessor program with the ability to compile and run on UNIX workstations, the CM-5 supercomputer, and MAC Transputers with no change in the code. The ELFM was used to conduct a series of fire experiments that indicated how current fire regimes differ from historical ones due to cattail (Typha spp.) invasion and longer and deeper water depths. In an Everglades dominated by cattail, the predicted average annual area burned and fire frequency were significantly reduced by 23% and 21%, respectively. The ELFM experiments also suggested that altered hydroperiod has changed fire patterns by reducing fire frequency 63% while increasing fire size during drought years. Airboat trails did not significantly influence total area burned in the ELFM. However, they did seem to function as breaks in upwind fires and tended to reduce the size of potentially large fires.