Fire intensity and shrub regeneration in palmetto-dominated flatwoods of central Florida

HIERRO, J.L.; MENGES, E.

FLORIDA SCIENTIST

Allen Press

Año: 2002 p. 51 - 61

0098-4590

Fire intensity variation has the potential to affect vegetation dynamics in Florida ecosystems, but this has been little studied. In a south-central Florida pine flatwoods, we manipulated fuel loads before a prescribed fire. We then monitored maximum temperatures in the soil during the burn and characterized shrub stem dynamics before and periodically postfire for four years. Added fuel biomass exceeded the biomass of naturally occurring fuels, which varied significantly among sites. The addition of fuel significantly elevated maximum soil temperatures during the burn. All 12 shrub species found prefire persisted in our plots, and nine new shrub species appeared postfire but remained uncommon in our plots. Fuel additions did not affect the plot-level shrub species richness, overall shrub stem density, or species’ stem densities. Richness initially decreased following the fire, then rapidly increased to prefire levels and remained fairly constant for four years. Overall shrub stem density increased from one to nine months after the fire, and subsequently stabilized. Quercus minima and Ximenia americana increased rapidly in stem numbers postfire and Helianthemum nashii showed a delayed increase. Other species such as the two palmettos (Serenoa repens and Sabal etonia) were fairly stable. Our results emphasize that only very intense fires should be expected to markedly alter the stability of postfire responses of pine flatwoods.