The Florida Scrub
Visit a vanishing natural treasure.
Florida Scrub is one of the most interesting and one of the most endangered natural plant communities in the United States. Florida Scrub is a unique plant community that occurs in small patches scattered across the state. It is home to dozens of plant and animal species that occur nowhere else in the world.
What you'll see...
Follow this Track to learn about this fascinating ecosystem. You will be introduced to scrub ecology and the native plants and animals that have adapted to life in the scrub. And, we will give you directions should you decide to visit the scrub on your next trip to Florida!
So what is a scrub?
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 every time 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.
Where is the scrub?
Florida scrub develops on dunes and ridges behind wave-washed sandy beaches. It also develops in fire shadows, where the frequency of ground fires is reduced, down-wind from natural fire breaks such as streams and wetlands. Florida scrub occurs in patches along the northern Gulf Coast and along the lower Atlantic Coast, and throughout the peninsula as 'islands" within the pine savannas that covered Florida before modern man's arrival. Scrub is Florida's oldest plant community, and the scrubs on the Lake Wales Ridge are the oldest of all.
The Lake Wales Ridge scrubs occupy remnants of ancient beaches and sand dunes that marked Florida's shoreline millions of years ago when sea levels were 100' higher. As the sea level receded, the beaches were left behind. The long isolation of the Lake Wales Ridge scrubs has permitted the evolution of unique plants and animals and is the last remaining habitat for many that were once more widespread. The white sands of the scrubs along the Lake Wales Ridge in the center of the peninsula are clearly visible in this satellite photograph of Florida. (The conspicuous rectangle west of the southern end of the Ridge was cleared in the late nineties of all vegetation in preparation for a huge orange grove!)
Adapting to life in the scrub...
The plants of the Florida scrub are especially adapted to life in a harsh environment. In order to adapt successfully to life in the scrub, plants must:
- avoid being eaten
- survive occasional fires
- deal with heat and little water
How not to be had for dinner...
Many scrub plants are adorned with thorns and spines. Many scrub plants are highly aromatic, containing volatile oils. These chemicals protect the plants from being eaten. They give the plant a strong taste and smell (like camphor, peppermint, or oregano). In some cases these oils simply make the plant taste bad. In others they are toxic and could kill the diner. At least one Florida scrub plant has been shown to have important insecticidal properties. Others may have medicinal uses. Most have not even been investigated.
Most scrub plants resprout from underground stems, rhizomes or roots after a fire. Others are killed by fire but replace themselves with seeds already stored in the soil. The sand pine (the only kind of tree normally found in scrub) retains its seeds in sealed cones on its branches until it burns to death.
Dealing with heat and lack of water...
Most scrub plants do not have long taproots - the water table is too far below the sandy surface; instead, their roots are massed near the surface to take advantage of condensation and Florida's brief afternoon thunderstorms. Because there is no tree canopy in scrub, temperatures drop rapidly when the sun goes down and that causes moisture to condense on the leaves. The moisture then falls in drops right above the roots.
Many scrub plants have waxy-covered or curled leaves to resist evaporative water loss. Some have hairs (called pubescence) on the underside of the leaves to resist evaporation by maintaining high humidity at the surface. These hairs also increase the surface area for dew to form on. The needle-like leaves of many scrub plants may reduce evaporation (which occurs from the leaf underside) during the daytime, and provide increased surface area for dew to form on at night. This scrub holly has curled, spiny leaves that are oriented vertically, the better to direct water drops to its own roots.
Florida scrub is dominated by woody shrubs and herbaceous perennials. Annuals and trees are rare. There are few grasses in scrub, and no turf-forming grasses at all, only bunch grasses. The diversity of plant species in Florida scrub is lower than for other Florida plant communities. Only a couple hundred species of plants have adapted to the scrub environment. Perhaps because it is such a harsh environment, there are almost no introduced species in scrub. 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, it is truly amazing that scrub is (so far) immune to the invasion of foreign weeds. Knock on sand pine.
Many scrub plants are beautifully suited for xeriscaping, the practice of landscaping with plants that can tolerate droughts and don't need to be watered. Most scrub plants require light, well-drained sandy soils and cannot tolerate clayey or moist soils. Fungus and various root rots attack scrub plants that have been planted in heavy soils or watered too much. Most scrub plants do best in full sun but a few can tolerate some shade.
Many scrub shrubs respond well to heavy pruning. Several of the typical scrub shrubs would make fine hedges. Some of the herbaceous perennials in scrub are among Florida's most beautiful. Florida's unique scrub plants are just beginning to be noticed by the horticultural community. Several, but not all, are currently available from native nurseries, primarily in central Florida (sources are provided at the end of the presentation).
Take a side track to our Gallery of Typical Scrub Plants for profiles and pictures of some of the Scrub's most common plant species.
Animals of the Florida Scrub
Florida scrub originally existed as "islands" within a landscape of pine flatwoods, high pine communities and wetlands. In general, the larger animals move freely into and out of scrub. Most birds, as well as black bears, bobcats, raccoons and other mammals visit scrub but can't be considered strictly scrub animals. There are only a few vertebrates that are totally restricted to scrub. Florida's famous scrub jay is probably the most well known scrub endemic (organism that occurs nowhere else). There are several species of lizards and snakes that are practically restricted to Florida scrub. Some of these, such as the sand-swimming sand skink, and the peninsula mole skink pictured here, are highly adapted to life in the scrub. By one count there are at least 40 species of spiders and insects that are known to be restricted to Florida scrub. There are probably many more yet to be discovered.
Take a side track through Floridata's Gallery of Scrub Animals and meet some of the critters that have adapted to survive in Florida's harshest habitat.
The scrub's disappearing plants...
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. Of these, about 20 are endemic to scrubs on the Lake Wales Ridge only. Most of these are considered Endangered or Threatened by the US Department of Interior and the State of Florida because their distributions are so small that they are vulnerable to extinction. Some are known from only 2 or 3 localities and may go extinct within a few years. One species, a thorny shrub in the jujube genus Ziziphus, was thought to be extinct but was recently rediscovered near Avon Park after 40 years. The beautiful flower pictured here belongs to the Endangered long-spurred balm (Dicerandra cornutissima) which is endemic to a handful of scrubs in the vicinity of I-75 and the Marion-Sumter County line in north central Florida.
In a vanishing world...
The ancient scrub of the Lake Wales Ridge has been reduced from over 80,000 acres a hundred years ago to less than 25,000 acres today. Citrus groves and subdivisions have replaced rosemary balds and scrub jays.
The trend continues but recent efforts to preserve remnants of Florida scrub have resulted in a few scrub sanctuaries. The Nature Conservancy has established a half dozen scrub preserves on the Lake Wales Ridge. Florida's Conservation and Recreational Lands (Preservation 2000) program is currently buying Florida scrub for protection. The US Fish and Wildlife Service has recently begun purchasing remnants of ancient Lake Wales Ridge scrub around Sebring and Avon Park for a new national wildlife refuge, the nation's first ever dedicated primarily to plant conservation.
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. Without periodic fires, the scrub oaks grow into trees, and the unique scrub plants and animals are shaded out as in this photo. Prescribed fires, set by trained land managers, are necessary, but often resisted by neighbors.
Visiting the Florida Scrub in real life...
If you are interested in seeing the Florida Scrub for yourself, this page will guide you to some of the best examples of these unique communities. Contact information and web site addresses for the organizations mentioned below can be found on the next page.
Scrub remnants occur on undeveloped dunes along the northern Gulf coast from Carrabelle to Pensacola and on some of the few remaining undeveloped dunes on the Atlantic Coast from Titusville to West Palm Beach. The "Big Scrub" of the Ocala National Forest in Marion and Lake Counties is managed for commercial pulp wood production, but many scrub plants still persist within the clearcuts.
Several of Florida's state parks contain examples of typical Florida scrub. These include Gold Head Branch, Lake Kissimmee, Jonathan Dickinson, Cedar Keys, Rock Springs and Wekiva Springs State Parks. Lake Arbuckle State Park and Lake Arbuckle State Forest contain examples of ancient Lake Wales Ridge scrub.
You can see Lake Wales Ridge scrub at The Nature Conservancy's Catfish Creek, Tiger Creek and Saddle Blanket Lakes Scrub Preserves in Polk County and at their Lake Apthorpe Scrub Preserve in Highlands County.
One of the best ways to see the Lake Wales Ridge ancient scrub is to take some of the side roads off US-27 between Lake Wales and Lake Placid. If you stay within 10 miles of US-27, you'll see the white-sand patches of scrub in undeveloped lots and road shoulders. Within these remnant patches of ancient scrub, you can expect to see many of the endangered scrub plants!
Some of the best Lake Wales Ridge scrubs are preserved on the Archbold Biological Station in Lake Placid, Florida.
On your next visit to Disney World and central Florida why not visit the Scrub? The peace and beauty of the Lake Wales Ridge scrub is only an hour's drive away and will provide a soothing change of pace from the excitement of central Florida's other attractions.
Want to learn more?
The US Fish and Wildlife Service's Endangered Species office in Jacksonville has information about the Florida scrub, and about the new Lake Wales Ridge National Wildlife Refuge: (904) 232-2580.
Visit the Florida State Park web site for more information about seeing "The Real Florida" in person: http://www.dep.state.fl.us/parks/index.html.
The Nature Conservancy's Lake Wales office can direct you to more information about their projects in Florida scrub.
Archbold Biological Station has a staff of scrub experts and a library of scrub information.
Dr. Steve Christman, the author of this Track, is available to conduct guided tours of the Florida scrub.