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 manipul ate, especially at a landscape level. An Everglades Landscape fire mod el (ELFM) was developed using parallel-processing algorithms and trans puter-processors to understand fire behavior in Water Conservation Are a 2A (WCA 2A) in the Everglades. Fuel characteristics, water depth, wi nd velocity and direction, rainfall, lightning, and humidity determine d the physical state and rate at which fire spreading and spotting occ urred in the ELFM. The ELFM simulated fire spread across a heterogeneo us landscape using a grid-based system. Parallel processing enabled th e model to simulate fire on a large spatial scale with fine resolution (i.e., 1755 x 1634 pixels with 20 x 20 m resolution). The model was d esigned as a multiprocessor program with the ability to compile and ru n on UNIX workstations, the CM-5 supercomputer, and Mac Transputers wi th no change in the code. The ELFM was used to conduct a series of fir e experiments that indicated how current fire regimes differ from hist orical ones due to cattail (Typha spp.) invasion and longer and deeper water depths. In an Everglades dominated by cattail, the predicted av erage annual area burned and fire frequency were significantly reduced by 23% and 21%, respectively. The ELFM experiments also suggested tha t altered hydroperiod have changed fire patterns by reducing fire freq uency 63% while increasing fire size during drought years. Airboat tra ils did not significantly influence total area burned in the ELFM. How ever, they did seem to function as breaks in upwind fires and tended t o reduce the size of potentially large fires.