Coastal Plain

Physical Landscape
The Coastal Plain of Georgia stretches from the fall line to the Atlantic Ocean, covering 35,650 square miles (60% of the state).  The Coastal Plain was once a sea floor and is composed mainly of unconsolidated sediments with little hard rock at the surface. Coastal Plain sediments originated in the Piedmont and even in the mountains beyond and have been deposited over thousands of years.  Near the fall line the Coastal Plain can be highly dissected but it becomes nearly completely flat closer to the coast. The current soils of the Coastal Plain tend to be sandy, a result of prehistoric oceans advancing and retreating across them. Prehistoric wave action dissolved and reduced soils to the sturdiest of substrates, quartzite or sand.

The Coastal Plain typically has a moderate climate with hot humid summers and mild winters.  There is an average of 51 inches of rain, which comes from both convective thunderstorms in spring and summer and occasional hurricanes in fall.

Habitat Highlight: Longleaf Pine-Wiregrass Community
The Longleaf Pine-Wiregrass community is unique to the Coastal Plain and among the most endangered habitats in the United States.  This is made more significant by the fact that the extent of Longleaf Pine (Pinus palustris) forests just 200 years ago was almost unimaginably large.  It is estimated that over 90 million acres of Longleaf Pine forests stretched from Texas throughout the gulf coast states, peninsular Florida, Georgia and up the east coast to Virginia.  Currently, only several thousand acres of good quality old-growth Longleaf Pine remain scattered throughout the southeast.  The remaining stands of Longleaf Pine are mostly found on private quail hunting plantations and military land. Longleaf Pine forest was without a doubt the dominant woodland of the Southeastern coastal plain before European settlement.

Longleaf Pine trees tend to grow widely spaced, creating an open park-like forest.  Sometimes these forests appeared more like grasslands with scattered pine trees than true forests.  At first glance a Longleaf Pine-Wiregrass forest appears to be composed of only two or three species, but the herbaceous understory forms one of the most diverse plant communities north of the tropics.  In some areas over 40 plant species per square meter is not uncommon.  In all, hundreds of species of grasses, legumes and other herbaceous plants grow beneath the pines.  Many of these plant species are only found in the Longleaf Pine forest. Another defining feature of the Longleaf Pine forest and one that played an important role in its decline, is the forests dependence upon fire.  In fact, fire is a crucial factor in maintaining many plant communities and is absolutely essential to the survival of the Longleaf Pine Wiregrass community.  Without fire hardwoods grow up through the Longleaf Pine, competing for light, nutrients and space.  Fire suppression throughout much of the last century contributed to the decline of Longleaf Pine forests.

Historically, fires started by lightning strikes swept through the understory every three to five years, burning back shrubs and hardwoods. Mature Longleaf Pine were protected from fire by thick heat-resistant bark.  Native Americans also burned the understory to manage for game, and early European settlers burned to maintain good forage for cattle in forest understory.

Blow downs are the chief natural cause for mortality among mature Longleaf Pine trees. Older trees rise above the canopy, exposing them to direct wind.  Without windstorms, it seems that the Longleaf Pine trees show very little signs of aging and can live for many hundreds of years.  

Key Plants: Longleaf Pine
The namesake of the Longleaf Pine forest is a tree with a fascinating natural and cultural history.  Its dependence on fire and unique growth strategy set it apart from most other trees.  Its cultural history is as interesting as its natural history, and much of the United States was built with Longleaf Pine.  It is estimated that 200 billion board feet of lumber were cleared from these southeastern forests over the last 200 years.

Every stage of the Longleaf Pines life depends on fire.  The seeds require bare mineral soil to germinate.  These soils are typically found after a fire has burned off the leaf litter.  The germinated seed grows into the grass stage, which looks like a low growing bunch grass.  Closer observation will show that the leaves are actually pine needles.  The Longleaf Pine can remain in the grass stage for many years, awaiting a fire to clear the way for its growth.  The dense clusters of needles protect the growth cells from this releasing fire.  After a fire burns through, clearing brush away from the pine seedling, the tree enters the rocket stage. This involves a rapid period of growth during which the tree is vulnerable to fire.  Once freed from the understory, the tree can continue to grow and eventually become a canopy tree.  As it grows, it develops thick bark that protects it from subsequent fires.

Key Animals: Birds
The Red-cockaded Woodpecker (Picoides borealis) and the Bachmans Sparrow (Aimophila aestivalis) are two birds that are dependant upon the Longleaf Pine forest.  The Red-cockaded Woodpecker (RCW) is listed as an endangered species largely due to its exclusive dependence on a diminished habitat.  As habitat specialists, RCWs require large old pines suffering from red-heart rot, a disease that softens the wood enough for them to drill nest holes.  RCWs are the only North American woodpecker to nest in living trees.  This means that building a nest hole is a difficult task that can take years to complete.  This fact leads to high site fidelity in areas with cavities already excavated and has led managers to create artificial cavities for RCWs.

Predators, such as rat snakes and other woodpeckers, can significantly decrease nest success.  In order to discourage predators RCWs often drill many small holes around their nest hole to release sap making it difficult for snakes to get into the nest.

Habitat Highlight: Carolina Bays
A unique wetland feature of the Southeastern Coastal Plain is the Carolina Bay.  Carolina Bays are oval or teardrop shaped wetlands oriented along a Northwest-Southeast axis, and are found from Maryland south to Georgia.  Some support permanent lakes while others experience more irregular water levels.  Carolina Bays range from 6 to 30 feet deep and from several acres to 6,000 acres in size.  Due to varying water levels, the vegetation differs dramatically from one Bay to another.  Some are characterized by cypress forests, others marsh and some shrub bogs.  Georgia is home to more than 1,000 Carolina Bays, covering 250,000 acres.

The unique distribution, shape and orientation of Carolina Bays have generated some interesting speculation about their origins.  Some hypothesized that meteor showers caused craters, which then filled with water. This dramatic origin is supported by the similar alignment of the Bays, but no meteoric fragments have been found. A more probable hypothesis suggests that gale-force winds during the last glacial period scooped these depressions out of the sandy soil.  Sandy ridges occurring on the eastern side of many Carolina Bays support this hypothesis.  Whatever their origin, Carolina Bays along with cypress and gum ponds are important inland wetlands that provide habitat for a wide range of plants and animals.

Carolina Bays are underlain by a clay layer that keeps the water from draining through the otherwise porous soil of the Coastal Plain. Carolina Bays tend to be isolated from other bodies of water, so their only access to water is rainfall.  Water loss comes from evaporation and plant transpiration.

Carolina Bays tend to have some peat development, which is a layer of partially decomposed plant matter.  Peat forms when plant production exceeds the rate of decomposition.  Decomposition rates are slow in wetlands due to the lack of oxygen in the soil.  Several Georgia Bays have peat deposits over 14 feet deep, the end product of about 9,000 years of plant decomposition.

Peaty saturated soils tend to become highly acidic (pH 4.5) creating a stressful environment for plants, leading to a limited plant community.  Plants that can thrive in these oxygen poor acidic soils are called hydrophilic or water loving.  Pond Cypress (Taxodium acendus) dominate in bays that are flooded for extended periods, while more irregularly flooded habitats maintain Blackgum (Nyssa sylvatica), Red Maple (Acer rubrum) and Pond Pine (Pinus serotina) as well.  Pickerel Weed (Pontedara cordata) and Water Lily (Nymphoea stellata) dominate open water habitat.

Though it may seem counterintuitive, fire plays an important role in the maintenance of Carolina Bays.  During dry periods, peat becomes flammable, and lightning strikes can ignite fires that burn off woody vegetation and layers of peat.  Historically, Bays probably burned about every 25 years, keeping them from growing over with vegetation.  This is a great example of how a disturbance regime can play an important role in habitat maintenance.

Human impacts on Carolina Bays have been dramatic.  Many have been drained and cut for farming and timber.  Peat mining and fire suppression have both led to declining quality of our Carolina Bays.   Carolina Bays offer an excellent place to learn about the importance of wetlands in the Georgia landscape.  Unfortunately, wetlands are often viewed as inhospitable wastelands, dominated by things that bite, sting and otherwise impede human progress.  This attitude has led to a loss of more that 50% of our wetlands in the US and threatens many of our unique wetlands in Georgia.

The benefits of wetlands are hard to overestimate.  They provide critical habitat for many plant and animal species that could not survive in other habitats.  They are also critical for water management as they absorb and store vast quantities of storm water, helping reduce floods and recharge aquifers.  Not only do wetlands store water like sponges, they also filter and clean water as well, absorbing toxins and other pollutants. 

Key Animals: Altamaha Spinymussel
The Altamaha Spinymussel (Elliptio spinosa) is found only in the Altamaha River drainage of Georgia.  This animal reaches a length of about four inches, a height of nearly three inches and is dark greenish to black in color.  What makes this species so interesting is the three to five, long spines that develop on each of its valves (shells).  The spines begin growing when the mussel is a juvenile and can reach an inch or more in length.  However, they often break off as the mussel gets older and many adult individuals show little evidence that a spine was ever there.  It has been suggested that the spines help to anchor the mussel in the sandy habitats of the Altamaha River drainage.  There are two or three additional spinymussels in North America but none as large and handsome as the Altamaha Spinymussel.

Key Animals: American Alligator
The American Alligator (Alligator mississipiensis) is our largest reptile in Georgia.  Today it is rare for one to exceed 14 feet in length, but alligators have reached over 19 feet. Alligators have lived mostly unchanged for 180 million years, coexisting with and surviving the extinction of the dinosaurs.  Until human settlement in the Southeast they remained the unchallenged rulers of swamps and bayous from Texas to North Carolina.

Due to excessive hunting and wetland draining, American Alligators were placed on the Endangered Species list in the 1970s.  In the last 30 years American Alligators have made a remarkable comeback, and there are currently an estimated 2 million Alligators in the southeastern United States.

Alligators serve many important roles in the swamps of Georgia.  They keep rodents and other grazing species under control.  Alligators also create wallows, which stay wet even if the surrounding swamp dries out.  These wallows or gator holes provide watery refuges for aquatic plants and animals that would otherwise dry up and die during times of drought.

Key Plants: Pond Cypress
The Pond Cypress (Taxodium acendus) is the dominant tree in still water wetlands.  The similar Bald Cypress (Taxodium distichum) prefers moving water wetlands.  Both are impressive trees that can reach 150 feet tall and live over 900 years.  They are deciduous conifers, shedding their needles in late November and re-growing them in March. Cypress require varying water levels at different stages of their life history.  Cypress seeds need bare wet soil to germinate, while the adults dominate in flooded areas where other trees cannot survive.  The most distinctive features of both Cypress species are the splaying buttresses at their base and the cypress knees projecting above the ground surface.  The buttresses provide structural support in the muddy soils. It is thought that the knees may aid in gas exchange allowing oxygen to reach the roots despite saturated soils. 

Both species of Cypress are valuable timber species, and many of the states most impressive stands have been cut.  The wood is of particular value due to its resistance to rot and insect infestation.

Key Plants: Pitcher Plants
Throughout the Coastal Plain, wherever there are bogs, wet savannas, low areas in Pine Flatwoods and other wetland habitats, a variety of Pitcher Plants (Sarracenia sp.) may be found.  Pitcher Plants are a fascinating group of plants adapted to the low nutrient soils of wetlands.  In order to meet their nutrient requirements, Pitcher Plants are carnivorous, feeding off a wide variety of insects.  Georgia has 7 species of Pitcher Plants, some of which can be found in the Piedmont and Mountains but most are restricted to the Coastal Plain.  All of our Pitcher Plants are protected due to concern over their declining populations.  The Green Pitcher Plant (Sarracenia oreophila) is Federally Listed as an endangered species.

Pitcher Plants have tube-shaped leaves (known as the pitcher) that form a trap when partially filled with water. Insects are lured into the pitcher with sweet nectar.  A waxy layer on the inside of the pitcher, coupled with many downward pointing hairs, makes it difficult for insects to escape.  Once they fall into the water, they drown and are digested by enzymes the plants produce.

Building a Pitcher Plant Bog is a fairly easy way to encourage children to observe these carnivorous plants close up.

Other Key Species:
Alligator Snapping Turtle (Macroclemys temminckii) Our largest freshwater turtle, the Alligator Snapping Turtle is a species of concern in Georgia.  It can reach 300 lbs in weight.
Sandhill Crane (Grus canadensis) grazing disturbance helps maintain open prairie in Carolina bays and the Okefenokee.
Shermans Fox Squirrel (Sciurus niger shermani) The largest North American squ