Florida's Scrub Communities
The Florida scrub communities are very old ecosystems, some of which have been in existence for as long as a million years. Scrub communities are characterized by the presence of mostly shrubs, in contrast to forests dominated by trees, and savannas and prairies dominated by grasses.
Three main types of scrub communities exist in Florida. The names indicate the dominant plants of these communities. The Oak Scrub is a hardwood community with clumped patches of low-growing oaks such as myrtle oak, Chapman’s Oak, and sand live oak interspersed with patches of bare, white sand. The Sand Pine Scrub is dominated by an overstory of sand pine, but an understory of oaks and other plants may be present. The Rosemary Scrub has few or no sand pines or oaks, but is dominated by rosemary and lichens which grow in open areas.
Plants living within the scrub areas must be able to endure a very harsh environment. Scorching summer temperatures are often the norm because very little tree canopy is present to block the sun’s penetrating rays. Water drains through the deep, infertile sand almost as fast as it falls, for there is little to no organic matter to hold moisture or nutrients. Fires sweep through from time to time, and the loose sands are swept around by desiccating, salt-laden wind which sometimes buries small plants. Only the toughest can survive. Some that have managed to adapt to this environment occur nowhere else in the world, so it is an often studied community.
Scrub habitat can be found in three major areas in Florida; the coastal panhandle, the coastal peninsula, and the inland peninsula. The scrub in this article is the coastal panhandle, specifically that in Henderson Beach State Park
in Destin, Florida. A trip to this park with my horticulture studies group was an eye-opener. In places the vegetation is like something you might see in a desert. In other places, the ground is nearly covered with vegetation, but none of it is very large or vigorous. Primary vegetation includes the sand live oak (Quercus geminata), myrtle oak (Quercus myrtifolia) and Choctawhatchee sand pine (Pinus clausa var. immuginata).
Our group was especially lucky, for during the time of our visit, the rare a threatened Gulf Coast lupine (Lupinus westianus) was in full bloom. Like other members of the Fabaceae or pea family, this deep-rooted plant is capable of fixing nitrogen from the atmosphere. Gulf Coast lupine is commonly found on exposed and active sand dunes and on disturbed areas. Living only 4 to 6 years, it produces copious seeds that remain viable for many years.
Growing along with the lupine in open areas was Florida rosemary (Ceratiola ericoides) the namesake of the rosemary scrub. This rounded shrub has numerous erect branches arising from the base, giving it a rounded appearance. The only member of the Ericaceae (heath) family found in Florida, it is distinguished by very narrow, turned under leaves in four rows and a greenish yellow fruit. The evergreen shrub has wide ranging roots to capture any available moisture and nutrients. Few plants out compete it, for it has chemicals that prohibit the growth of other plants. This rosemary is not to be confused with the genus Rosmarinus, the rosemary cooking herb of the Lamiaceae family.
Interspersed with the rosemary is another blue-flowering sub-shrub, Conradina canescens or false rosemary, which grows so thick in some places that the ground seems covered with a pale blue blanket when it is in bloom. Peak bloom occurs in late spring. Since it is more adaptable to varying soils than many scrub plants, it makes a significant spot of color along not only the dunes, but also along the interstates and highways of Florida.
Somewhat surprising is the presence of other plants often seen in forested areas a bit farther north; however, they are noticeably different in character. As a result of the constant salt-laden breezes and occasional hurricane force winds, the dwarfed and contorted trees lean away from the prevailing wind. Present are magnolia (Magnolia grandiflora), yaupon (Ilex vomitoria), saw palmetto (Serenoa repens), Virginia red bay (Persea borbonia), and many other familiar trees. Herbaceous plants, too, seemed a poor representation of their species due to the low nutrient content of the scrub soils and other aspects of their harsh environment.
While the scrub areas are beautiful and rare, serious threats to their stability exist. Threats are mostly human related and include conversion of the habitat to housing and urban development, incompatible forestry practices, agriculture, commercial and industrial development, deposits of dredge spoil, conversion to recreation areas, and the damages caused by invasive animals and plants.
Residents and visitors alike agree that the scrub communities exhibit their own kind of beauty. Upsetting to all who treasure the rare plant communities of the world, the rare Florida Scrub is one of many declining habitats. According to the GIS (Geographic Information Systems), about 337,458 acres of scrub habitat exist in Florida. About 76% is in protected or managed areas, while the remaining parts are mostly private lands. It is up to all of us who treasure these rare communities to protect them for future generations.