Scrub is a plant community characterized by the dominance of shrubs, in contrast to forests which are dominated by trees, and savannas and prairies which are dominated by grasses.

The Florida scrub environment is harsh. Without a canopy of trees, summer temperatures are hotter than in other plant communities. Rain water rushes through the deep, sterile sands as fast as it falls. Fires sweep through the bushes burning the scrub to the ground at unpredictable intervals. The loose sands are shifted about by wind, abrading and sometimes burying small plants. Only the toughest plants and animals can survive!

The scrub depends on fire...

In much of the world, and especially in the southeastern United States, lightning-set fires are a natural part of the environment, and the period between these fires determines what kind of plant community will grow on a particular site. This "fire-return interval" is itself determined by the lay of the land with respect to lakes, rivers and wetlands which act as natural firebreaks. Without firebreaks, everything would burn everytime lightning started a ground fire, which in Florida averages more than 8000 times each year!

And on how often it burns...

Under natural conditions, savannas and prairies burn every 1-5 years, and forests only once in a century or even less often. Scrub is maintained by fires that burn the plants to the ground at intermediate intervals of 30-75 years or so. The scrub-adapted plants then resprout from their roots or germinate from seeds that were already "banked" in the sand.