A majority of Florida is made up of pine woods, most of which burned at regular, frequent intervals prior to the last 100-200 yeaers. The overall ecosystem is fire-dependent, all the way down to the soils of the flatwoods. The pines don't particularly burn, but the understory will burn quite readily at the end of the dry season (i.e., now). Florida's non-aquatic ecosystems are as fire-dependent as are those of western states, and while fire suppression doesn't necessarily lead to mega-fires like at Yellowstone, the effects are significant, with hardwoods out-competing the native balance dominated by pine, grass and scrub.
Here's a few good links to UF's forestry website, the first on flatwoods, the second on scrub, the third on high pine/sandhills, that should answer most of the question of what's burning.
http://www.sfrc.ufl.edu/Extension/florida_forestry_information/forest_resources/pine_flatwoods.htmlhttp://www.sfrc.ufl.edu/Extension/florida_forestry_information/forest_resources/scrub.htmlhttp://www.sfrc.ufl.edu/Extension/florida_forestry_information/forest_resources/scrub.html