The term swamp brings to mind a dark place, full of large spooky trees, overhanging with Spanish Moss, still… green… stagnate water that has the odor of rotten eggs. It is quiet with little wind blowing at all. What noises you do hear are the shrill of some strange bird, the croak of a large bullfrog, and maybe the snap of branch caused by some unknown creature… maybe a large one… uneasy feeling – the feeling you are being watched. It is the place of legend and lore from this part country that goes back centuries. It is a place we would really rather not go in alone, yet there are many humans that call this place home. Their families have lived in this ecosystem for generations and they know what to do, when to do it, and when not to do it. The popularity of the recent cable program SWAMP PEOPLE has brought to light recently our fascination with this environment and has actually spawned an ecotourism industry all over the gulf coast. Airboat rides through a swamp to view dangerous wildlife has become big money for many folks.
But what about the REAL story of swamps? What is it really like in there? We will begin with a working definition of the system. When we think of a swamp we immediately think of southLouisianaand the Florida Everglades. Much of this area is swamp, but not all – a lot of it (actually in theEverglades… most of it) is marsh. So what is the difference? A swamp is defined as a wetland whose dominate vegetation is a woody plant, usually trees. A marsh in turn is a wetland whose dominate vegetation is herbaceous, usually grasses like sedges and rushes. Swamps generally have tall trees, little sunlight, and little wind. Marshes are generally open, you can see for miles, and there can actually be quite a bit of wind. The wildlife in the two systems can be quite similar but there are species that are restricted, for abiotic or biotic reasons, to one system or the other.. In Florida we have two types of swamps; the hardwood/cypress swamp we are all familiar with and the mangrove swamps of the coastline. In mangrove swamps the standing water is actually salty and the trees that live there, mangroves, have adapted to this. This system is tropical and not found in the panhandle of our state.
The swamps of Escambia County are all hardwood/cypress and the water standing within them can be relatively shallow or to depths of up to six feet. The water flow in most of these systems is relatively slow and so leaf litter from the trees fall to the bottom and remains. Here they are decomposed by micro-organisms which release nitrogen and phosphorus back to the feeding plants. As they decompose the leaf material they consume a lot of oxygen so the soil and the water here is generally HYPOXIC (low in oxygen). The plants living here then must find ways to acquire oxygen from other sources than the soil. Cypress (Taxodium distichum) tend to do this by producing what are called KNEES. These are bulbous extensions of the root system above the water line that can be used to acquire atmospheric oxygen for the plant. Other plants here have other mechanisms for doing the same thing. Because of the hypoxic state of the soils many plants cannot live in swamps. As these micro-organisms breakdown the leaf litter oxygen levels can become so low that only ANAEROBIC (no oxygen) microbes can survive. These microbes not only breakdown the leaf litter but they release hydrogen sulfide gas (H2S) which smells like rotten eggs; many refer to this as SWAMP GAS. Hydrogen sulfide is quite toxic to life and thus can reduce the variety of plants and animals even more; thus plant diversity in a swamp is relatively low.
There are basically two types of hardwood/cypress swamp in Florida; Seepage and Floodplain Swamps. SEEPAGE SWAMPS form in low places around the county where ground water levels meet the surface layer. These swamps are generally wetter during the rainy season and can be completely dry during periods of low rain fall. The most common type of tree found in this system would be the Bay trees. They do not experience fire because of the hydric soils, so pines and other upland species are not found here. Though the variety of trees is low their height is quite impressive; over 100 feet tall. This produces the classic closed canopy – dark forest floor that people expect to find in a swamp. As you might expect there are numerous flying, crawling, and biting insects; gnats, mosquitoes, black flies, yellow flies, all can be found here. Likewise insect eating animals are quite numerous. Woodland birds are here in great numbers as are a variety of salamanders and frogs. Reptiles would include several species of plant and animal consuming turtles, numerous varieties of amphibians and carnivorous water snakes, and the alligator is also quite common. Most of the mammals are small like squirrels and shrews, but occasionally larger predators move through including black bear and bobcats; raccoons are also quite common. In our area of the panhandle we have a few remnants of a type of seepage swamp referred to as the WHITE CEDAR SWAMP. These were never very numerous but many of those that were here have been removed for logging interest. Like the Bay Seepage Swamps they experience periods of wet and dry and their ecology changes with the seasons. The White Cedar (Chamaecyparis thyoides) is resistant to many forms of microbial tree diseases. This made them very popular with home and furniture builders and many standing forests are now gone. Those that still exist in Escambia and Santa Rosa counties can reach a height of 100 feet and are over 200 years old.
The second type of hardwood/cypress swamp found here is the FLOOD PLAIN SWAMP. During rainy seasons most of our rivers flood their banks and form elevated beaches called RIDGES. Behind these ridges are areas of flat land where standing water can last for days or weeks, maybe longer. Like seepage swamps the soil is very wet, low in oxygen, and low in nutrients. Trees that grow here have to be adapted to these conditions. Another difference found in a floodplain swamp is the presence of flowing water. At times the current speed can be quite high. There is plenty of evidence of where the high water flowed and how fast it was moving when you venture into these swamps. Wrack material (leaves and branches) as well as “log jams” can be found in numerous spots and sometimes quite high up the bank.
Because the water is moving here the oxygen content of the soil is a little bit higher and more species of wetland plants can survive. There are approximately 300 species of wetland plants in this system. The dominant trees here are Cypress and Tupelo (Nyssa sylvatica). Cypress trees can grow in hydric or mesic soils and can withstand fire; however there is less competition with other trees in the Floodplain Swamp and so they are most common here. They are famous for the “Cypress Knees” which are root adaptations of the plant to acquire atmospheric oxygen in the oxygen poor soils. The older members of the cypress tree community could reach 150 feet tall and wide enough at the base that a human could walk through it. A few of these ancient giants still remain in the Florida panhandle and some maybe over 1000 years old. The base of this tree widens to form what is called a BUTTRESS which helps these giant trees support their great weight. The wood is resistant to many insect pests and made this a popular tree in the early lumber industry in the panhandle. Getting to these trees was some what of a trick. There are some local accounts of how this was done. Basically the lumberman would venture into the swamp with the axes – select the trees to be felled that day – cut the tree down (with the expenditure of GREAT energy) – and use oxen to drag the trunks to the river; apparently oxen were the only animals that could pull them through this environment. Once the trunks reached the river they would then float to a sawmill downstream where the boards were cut.
The Ogeechee Tupelo is a shorter tree (25-30 ft tall) and has a hallow trunk. Leaf litter collects in this trunk where it decomposes and supports a microcosm community. All sorts of hallow branches branch off the main trunk producing a neat looking tree. The ridges that separate theFloodplainSwampfrom the main river are usually high and dry and form a more xeric community that includes Willow and Cottonwood trees.
As with the Seepage Swamp, Floodplain Swamps have their biting insects; flies, gnats, mites, ticks, beetles are all found here. One interesting insect here is the firefly. Those who have lived in the area for many years probably remember collecting these as a kid. There are a host of insect eating fish and amphibians. Many locals have learned the fine art of “fly tying” to try and catch one of these insect eating fish and thus become part of the Floodplain Swamp food chain. There are predators of these insect eating animals. Bullfrogs (Lithobates catesbeianus) are known to eat not only insects but worms, amphibians, small reptiles, and even small mammals. The Florida Cooter (Pseudemys floridana) is relatively large turtle found here that prefers the quiet backwaters of the river systems. They feed on a variety of small insects and worms when they are young but move to a vegetarian diet as an adult. Of the two snapper species, the Common Snapper (Chelydra serpentine) can be found here; their cousin the Alligator Snapper (Macrochelys temminckii) could be found here but prefers the flowing waters of the open river. 90% of our woodland birds use this habitat at some time during the year; either as a feeding area or for reproduction. Some of the predatory birds found include the osprey, the kites, hawks, owls, and even the bald eagle. A variety of small mammals can be found but also raccoon, opossum, black bear, bobcat, beaver, and the river otter have been seen.
Resources: Whitney, E., D.B. Means, A. Rudloe, (2004), Priceless Florida; natural ecosystems and
native species, Pineapple Press,SarasotaFL, pp. 423
Photos: Molly O’Connor – Roy Hyatt Environmental Center
Comments or Questions: Rick O’Connor, Escambia County Extension – firstname.lastname@example.org