Natural History: Florida high: now landlocked within the peninsula, an ancient dune preserves the st

Last August, when Hurricane Charley swept across Florida, one place it struck was the Lake Wales Ridge, an elevated region that runs like a spine down the center of the peninsula. About a hundred miles long and ranging between four and ten miles wide, the ridge reaches its highest point--about 310 feet above sea level--near its northern end. According to Hilary Swain, executive director of the Archbold Biological Station, near the south end of the ridge, many seventy- or eighty-year-old sand pines were snapped in half, and some bay trees were blown over, exposing their root balls. Further pummeled in September 2004 by hurricanes Frances and Jeanne, the area was extensively flooded, and in open areas the wind piled up sand into small dunes. But as devastating as the storms were to Florida's residents, nature survived her own onslaughts.

The Lake Wales Ridge, the oldest exposed land surface on the peninsula, comprises the remains of an ancient sand dune and beach ridge system that has stood above the ocean for perhaps 2 million years. Because of fluctuating sea levels, for large stretches of that time it was isolated from other landmasses. As a result, some of the plants and animals that lived there evolved into unique species. Today; many species that are endemic to the Lake Wales Ridge are rare, and quite a few are listed by the federal government as either endangered or threatened. Some of the endemics may always have been rare, but most are suffering from the loss of habitat, owing to the creation of citrus groves and other forms of development.

Nevertheless, through public and private efforts, critical parcels of land have been set aside to preserve some of the natural features. Among these lands are those of the Lake Wales Ridge State Forest, managed by the Florida Division of Forestry. Located near the town of Frostproof, the forest includes two major sections, the Arbuckle Tract, near Lake Arbuckle, and the Walk in the Water Tract, near Lake Weohyakapka (the Native American name, probably in the Seminole language, translates as "walk in the water").

Your first impression from these vantage points is that the ridge is a desert, because of all the sand and widely spaced vegetation. Even though the area gets, on average, between fifty-five and sixty inches of rainfall annually, the ridge is dry because the water percolates rapidly down through the sand. If you take a closer look, though, you can distinguish at least seven habitats.

The highest elevations of the ridge, where longleaf and slash pines dominate open forests, are known as sandhills. Most widespread around the sandhills is scrub, which is a desertlike habitat of sandy mounds with scattered clumps of vegetation. Many of the endangered and threatened organisms live here. At slightly lower elevations, where the water table comes close to the flat land surface, is a flat-woods with a mixture of pines, shrubs, and grasses and other herbs.

At even lower elevations, where standing water is often present, are two kinds of forest habitat. Near the base of the ridge slopes are swampy communities of fairly short deciduous and evergreen trees. Because various species of bay trees are prominent, the areas are known as bayheads. Adjacent to creeks are bottomland hardwood forests. A sixth kind of habitat, dominated by cutthroat grass, occurs where water oozes out from well-drained, sandy uplands; it is called a "seepage slope." Finally, during the rainier part of the year--May through October--the rising water table creates seasonal ponds in low depressions.

The federally listed animals that live on the ridge are the blue-tailed mole skink, the Florida scrub jay, and the sand skink (which seems to "swim" through the loose sand of the scrub). Other animals on the ridge are the eastern indigo snake (which can grow to more than eight feet long, making it the longest non venomous snake species in North America), the Florida black bear, the Florida gopher frog, the Florida mouse, the Florida pine snake, the Florida sandhill crane, the Florida scrub lizard, the gopher tortoise, Sherman's fox squirrel, and the short-tailed snake.

The gopher tortoise is particularly important because its burrows, sometimes as long as thirty feet, serve as homes for several of the rare species as well as many other more common organisms. The burrows also provide temporary havens when fires sweep through the area, or when temperatures reach high or low extremes.

The natural communities on the Lake Wales Ridge are adapted to withstand frequent fires. Although a few decades ago, land managers routinely sought to suppress fires, now they regularly conduct prescribed burns to maintain the habitats.

For millennia, hurricanes have also been a major element in this part of Florida. As Hilary Swain observes, it makes more sense to speak of the "effects" that the recent hurricanes have had on the area, rather than the "damage" they have caused. Periodic hurricanes may well have played an important role in maintaining species or ecosystems on the ridge.

ROBERT H. MOHLENBROCK is professor emeritus of plant biology at Southern Illinois University in Carbondale.

Habitats

Sandhill Longleaf pine is joined by blackjack oak, bluejack oak, sand post oak, and turkey oak. Plants beneath those trees include Curtiss' milkweed, dwarf pawpaw, shiny blueberry, and numerous kinds of grasses. The endangered Lewton's milkwort and even Florida jujube--one of the rarest shrubs in the United States--also live in the sandhills.

Scrub Endangered or threatened species include Britton's beargrass, Carter's mustard, Florida bonamia (a gorgeous member of the morning-glory family), Florida gayfeather (also known as scrub blazing star), Highlands scrub Saint-John's-wort, papery whitlowwort, pygmy fringe tree, scrub buckwheat, scrub plum, two kinds of jointweed, three kinds of leguminous plants (Avon Park rattlebox, Small's milk pea, and sweet-scented pigeonwings), and two members of the mint family.

Among the common trees and plants are big-flowered pawpaw, Chapman oak, Florida rosemary, myrtle oak, rusty staggerbush, sand live oak, saw palmetto, the scrub oak Quercus inopina, and scrub palmetto.

Flatwoods Longleaf and slash pines are the dominant trees above a diverse shrub layer of big gallberry, two kinds of small-leaved blueberries, gallberry, and saw palmetto. The early-spring-blooming yellow jessamine vine is usually present. Wildflowers include Bartram's rose gentian, pale meadow beauty, and variable-leaf sunflower.

Bayhead Sweet bay is the dominant species of bay tree. Other trees that grow in the bayhead soil, which is usually a nutrient-rich organic muck, are loblolly bay, red bay, and swamp bay. Among the many shrubs are highbush blueberry, small-leaf arrowwood, and swamp dogwood. Coastal Plain tickseed and sweet broom are common wildflowers.

Bottomland hardwood forest Cabbage palm, live oak, red maple, and sweet gum are prominent among the diverse species of trees. Dahoon holly, with its shiny evergreen leaves and brilliant scarlet berries, is a dominant shrub or small tree. Among the wildflowers are eastern bluestar and yellow crownbeard.

Seepage slope Cutthroat grass forms a fairly solid cover, interspersed with myrtle-leaved Saint-John's-wort, pine lily, and silver dwarf morning glory.

Seasonal pond Typical wetland plants include two kinds of arrowheads, common buttonbush, marsh mermaid weed, pickerelweed, yellow water lily, water hemlock, and an aquatic fern known as water spangles.