I always thought "scrub" was a derogatory term for lousy land, but from my time in Florida, I now know it denotes a disappearing and vital ecosystem. In fact, sand pine scrub is one of the oldest ecosystem types in Florida. Eons ago, when sea levels rose and inundated much of what is now Florida, these upland habitats were surrounded by water, forming desert-like hilltop islands, upon which many species of plants and animals developed unique adaptations to the harsh, dry environment of the scrub lands.
In short, scrub habitat refers to 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.) Furthermore, Florida scrub environment is harsh, for 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, and fires sweep through the bushes, burning the scrub to the ground. The loose sands are shifted about by wind, abrading and sometimes burying small plants. Hence, only the toughest plants and animals can survive.
These rare and unusual species are found nowhere else in the world. Currently, from 40% to 60% of the plants and animals in scrub lands are so rare they are threatened or endangered. Unfortunately, since scrub land is high and dry, it is also well suited for homes or agricultural uses, so these prime lands have been over-developed faster than any other ecosystem in the state, and two-thirds of the original scrub land in Florida has disappeared, exacerbating the wildlife habitat problem. And scrub land is also vital to man because it acts as recharge areas for the water table, making its survival all the more necessary and valuable.
Florida therefore is preserving these areas, and today we biked a bit of the multi-purpose trails at the Cedar Key Reserve (5028 acres) open to hikers, hunters (in season), equestrians, and mountain bikers. The Reserve has 2 access areas with small parking lots -- one on State Route 24 just west of the intersection with County Route 347, and the second on Route 347 just north of Highway 24. Both are only a handful of miles from the city of Cedar Key.
The trails allow a dozen or so miles of mountain biking. Areas as seen below travel nicely, where the uneven surface is solid and of dirt and grass and pine needles. But be warned -- the biking is extremely strenuous due to frequent lengthy sections of treacherous white sugar sand which make pedaling tricky and very slow-going.
Forested sections are also traversed, though the open areas predominate. The scrub is dominated by species such as sand live oak, myrtle oak, and Chapman's oak, rusty lyonia, and saw palmetto, and the reserve is home to the Florida Scrub Jay, Southern Bald Eagle, osprey, and various other birds, as well as turkey, feral hogs, bobcat, deer, foxes, gopher tortoises, and alligators.
The plants of the Florida Scrub have one advantage. In Florida, where exotic introduced species are a constant problem (from water hyacinths and hydrilla to Brazilian pepper and melaleuca and a hundred species in between), the scrub has been immune to the invasion of foreign weeds, thanks to thriving in such harsh conditions.
Plants and animals whose natural occurrence is restricted to one area are said to be endemic to that area, and such species are called endemics. There are no fewer than 40 species of plants that are endemic to Florida scrub, most of which are considered Endangered or Threatened because their distributions are so small that they are vulnerable to extinction.
Once acquired, the scrub preserves have to be managed. Since many are surrounded by roads, subdivisions or agricultural lands, managers cannot depend on natural lightning-set fires to reach the scrub, and without periodic fires, the scrub oaks grow into trees, and the unique scrub plants and animals are shaded out. Prescribed fires, set by trained land managers, are necessary, but often resisted by neighbors.
Here is the state's web page for the Cedar Key Scrub Reserve.
An excellent source for more info on Florida's scrub is FloriData.