Ecological Communities of the
Silver Springs State Park
Except for Hawaii, Florida contains more kinds of plants and animals than any other state. Plants and
animals found living together in the same area form a community. The types of plants and animals found
in a community depend upon abiotic factors including, temperature, moisture, soil types, and fire. The
Silver Springs State Park has seven different communities: scrub, flatwood, sandhill, xeric hammock,
mesic hammock, river swamp forest, and river (aquatic).
All of the communities found here have slowly been changing over the years. Eventually, some
of these communities, such as the sandpine scrub, may be replaced by other communities, such as the
xeric hammock. This process of change over time is called succession. This process takes hundreds of
years. Some communities such as scrub and sandhill must experience periodic fires in order to keep from
progressing further in the sequence of succession. The illustration below shows the successional
relationship among the communities of Silver Springs State Park.
The communities the seventh grade students will explore during their trip include the hammocks,
sandhill, river swamp and the river. Fourth graders will take a walk in the sandhill or hardwood swamp.
Community Succession at Silver Springs State Park
Mesic Hammock
Ocean
Old Dunes With
Residual Sands
Cross section of Florida
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Hlgh·Energy
Beach
Hammock Community
The word hammock is a Native American word that means "shady place." Hammock is a term
used in Florida to describe temperate hardwood forests. Hammocks are found throughout the state of
Florida. However, the composition, or types, of trees of the hammock changes from temperate forest
flora in North Florida to tropical flora in South Florida. Hammocks found in Marion County are made up
of different trees from hammocks in either Florida's panhandle area or in South Florida.
In North Florida, hammocks that are a mix of mostly evergreen and deciduous trees contain more
tree and shrub species in a given area than any other community in the continental United States. The
amount of overstory and understory trees in this type of forest is quite diverse. However, hardwood
broad-leaved trees are the major type of tree found. These trees form a dense canopy.
Hammocks can be divided into three types, or zones: xeric, mesic and hydric. The topography of
an area causes a gradation in the land. This gradation makes rain run-off from some areas and collect in
other areas. The difference in soil moisture causes distinct types of plants, which are adapted to water
levels, to live in the areas. Vegetation grows in zones based on varying moisture levels. These zones are
classified as xeric or dry, hydric or wet, and mesic or the midpoint between wet and dry. Hydric
hammocks are very moist and may flood. Xeric hammocks are dry and will not flood. Though mesic
hammocks are moist, they will not flood.
Hammocks are usually not large, expansive areas. They are usually narrow strips of land only a
few hundred meters wide. These hammock areas are usually confined between upland sandy pine areas
and lowland floodplain areas. At the Silver Springs State Park, the hammock is between the sandhill and
the river swamp.
Trees that form the canopy of the xeric hammock include live oaks, magnolia, and pignut
hickory. Live oak and pignut hickory are very important trees because their acorns and nuts support
many species of wildlife. Plants and trees found below the large overstory trees include crooked wood
trees, saw palmettos, grape vines, and blueberry bushes. Saw palmettos are also very important plants.
They provide shelter and food for many animals. A rare and special plant found in this area is the
greenfly orchid. This is an endangered epiphyte (air plant) that lives primarily on the trunks and branches
of live oak and magnolia trees.
The overstory trees of the mesic hammock are also live oak and magnolia. In this area one can
also find loblolly pines. The understory and ground plants include jessamine and grape vines, gallberry,
and bracken fern.
The loblolly pine makes up most of the overstory of the hydric hammock. though sweet gum and
magnolia trees are found here as well. The understory of the hydric hammock contains wax myrtle while
found growing in the damp soil are royal fern and cinnamon fern.
Animals that live in the hammocks are the flying squirrel, great homed owl, grey squirrel, white­
tailed deer, turkey, armadillo, diamondback rattlesnake, pygmy rattlesnake, and the coral snake. A
special animal that lives in the hammocks is the opossum. The opossum is the only marsupial (pouched
mammal) that lives in North America.
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Sandhill Community
The sandy, well drained soils of the sandhill community provide the perfect habitat for a number
of plants and animals. Longleaf pines and turkey oaks tower above wiregrass, prickly pear cactus, and
bear grass. Gopher tortoises dig their burrows in loose soil while pocket gophers build long tunnels in
the ground, searching for the roots of their favorite plants. Fox squirrels, bob white quail and indigo
snakes also make their homes in this dry community.
The sandy mounds that make up the sandhill community were once ocean dunes. The water
levels in Florida have fluctuated dramatically throughout the geologic eras. At times the coastline was
much farther inland. The remains of these ancient beaches can be seen in the sandy soil of the sandhills.
Low-intensity fire plays an important role in the sandhill community. If this community is not
burned every four to five years, other plants and animals begin to invade the area. Eventually the sandhill
community will success into the xeric hammock community. The species living in the sandhill community
have adapted to the frequent fires. The long burrows of the gopher tortoises provide protection from
flames for the tortoises as well as other small creatures. The longleaf pine and turkey
oak have thick, sturdy bark that is fire-resistant. Wiregrass thrives on fire and returns stronger after a
burn.
Unfortunately, 90% of the sandhill communities have disappeared. The well drained areas are
prime targets for human development. This loss of habitat affects the wildlife living in the area. Many of
the inhabitants of the sandhill, like the gopher tortoise and indigo snake, are endangered or threatened.
Sandhills
Small woody shrubs
Wire grass
Longleaf pines
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Swamp Community
More than 50% of Florida was once covered by wetlands. Today, more than half of those
wetlands are gone.
There are several types of wetlands. One type of wetland is the river swamp. A river swamp is a
forested wetland near a river. The number of these communities has been reduced across the state
because of drainage and filling. Ten percent of Florida's land area is still comprised of swamp
communities.
The river swamp is the type of wetland found along the floodplain of the Silver River. The
ground in the river swamp is moist. During parts of the year the area is covered with standing water. The
flooding in the swamp is caused by local rain. The water level can rise and fall rapidly in the swamp but
the area in the swamp can be flooded from one to seven months.
The water held in the swamp can be slowly released into the river, seep downward to recharge
the aquifer, or the water may evaporate into the atmosphere. Releasing the water slowly into the river
keeps the river from flooding surrounding areas during heavy rains.
As the water sits on the ground, the oxygen level in the soil decreases. The plants in the river
swamp community have adapted to survive during periods of low soil oxygen. The cypress tree has
developed a special root system in order to collect oxygen in the swamp. The cypress knees are growths
from the roots that "breathe" for the tree. One can see cypress knees sticking out of the moist soil in the
river swamp. Because plants need to be so specialized to in this community, there are few species that
can live there. The hydroperiod, or time the soil is saturated during the year, regulates the ecological
characteristics of the swamp.
Swamps are important not only because they recharge the aquifer and control flooding, but also
because they wildlife. For example, alligators build their nests in the swamps and other amphibians
require the standing water to lay their eggs.
Common trees found in the swamp are the cypress, black gum, red maple, pumpkin ash, dahoon
holly, and sabal palm. The sabal palm, or cabbage palm, is Florida's state tree. The terminal bud, or
heart, of the sabal palm is edible and often called swamp cabbage.
Plants found in the swamp are ferns, lizard tail, blue-flag iris, and epiphytes. Epiphytes, air
plants, are found in many communities. These plants are
relatives of the pineapple. Some vines found in this community
are poison ivy and climbing aster. Elephant ear is an exotic, or
non-native plant, that is prolific or capable of easily
reproducing. This plant is commonly seen along the river and
in the swamp.
Animals found in the swamp are alligators, red-tailed
hawks, crayfish, raccoons, black bears, feral hogs, armadillos,
and water moccasins. Hogs and armadillos are not indigenous,
or native, to Florida. Hogs were brought to Florida by the
Spaniards in the 1500's and the armadillo migrated from Texas
in the 1950's.
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Flatwoods
Cypress dome
Cypress strand
River and Springs Community
The Silver River is fed from one major spring and ten to twelve minor ones. Together these
springs gush approximately 530 million gallons of groundwater into the river daily. The combined flow
of all the springs is greater than any other group of springs in the world.
Florida's limestone foundation is filled with many cracks and crevices. Groundwater from rain
seeps down into the limestone and is stored underground in large reservoirs called aquifers. Most of this
water is trapped and cannot penetrate the layers of soil above or below it. When an opening is available
for the water, pressure forces water out of the ground, causing an artesian spring. Springs, like those at
Silver River, often form rivers.
The Silver River and springs form a community that is rich in shelter and nutrients. Plants and
animals that live in this habitat are well equipped to deal with their watery surroundings. Water lettuce
floats along the banks of the river and tape grass grows on the river’s bottom, providing food and shelter
for small fish and other aquatic creatures. The multitude of bream swimming in the river attracts water
birds such as anhingas and cormorants, both species of birds are excellent swimmers and divers. River
otters are mammals that are equally adept at swimming. Wading birds such as egrets, great blue herons,
and white ibis find their food closer to shore. Alligators and turtles sun themselves in the marshy weeds
before diving into the water in search of a meal. Raccoons are also frequent visitors to the water's edge.
Raccoons lack saliva glands and will wet their food before swallowing it.
The Silver River is connected to a number of other river communities. I t flows into the
Ocklawaha River, which joins the St. John’s River. The St. Johns River empties into the Atlantic Ocean
near Jacksonville. Altering one of these connecting waterways affects the Silver River. An example of
this chain of ecological reactions can be seen by the effects the Rodman Dam, located on the Ocklawaha
River, has had upon the Silver River. Manatees have historically sought refuge during the winter months
from the colder ocean temperatures in the warm waters of Silver River. The locks on the dam prevent any
manatees from swimming further inland. Mullet, once plentiful during colder months, are no longer seen
with regularity in Silver River.
I"
River and
Springs
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Ecological Community References
Alden, Peter, et. al National Audubon Society: Field Guide to Florida.1998
Myers, Ronald L. and John J. Ewel. Ecosystems of Florida. Orlando: University of Central
Florida Press, 1990.
Perry, John and Jane Greverus Perry. The Nature of Florida. Gainesville: The Sandhill Crane
Press, 1994.
Larson, Ron. Swamp Song: A Natural History of Florida's Swamps. Gainesville: University
Press of Florida, 1995.
Martin, Richard. Eternal Spring: Man's 10,00 Years of History at Florida's Silver Springs. St.
Petersburg: Great Outdoors Publishing Co.,1966.
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