Hammock is a term used in the

southeastern United States The Southeastern United States, also referred to as the American Southeast or simply the Southeast, is a geographical region of the United States. It is located broadly on the eastern portion of the southern United States and the southern por ...

for stands of trees, usually

hardwood Hardwood is wood from dicot trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen. Hardwood (which comes from ...

, that form an

ecological island An ecological island is a term used in New Zealand, and increasingly in Australia, to refer to an area of land (not necessarily an actual island) isolated by natural or artificial means from the surrounding land, where a natural micro-habitat exists ...

in a contrasting

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

. Hammocks grow on elevated areas, often just a few inches high, surrounded by

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

s that are too wet to support them. The term ''hammock'' is also applied to stands of hardwood trees growing on slopes between wetlands and drier uplands supporting a mixed or coniferous forest. Types of hammocks found in the United States include tropical hardwood hammocks, temperate hardwood hammocks, and maritime or coastal hammocks. Hammocks are also often classified as hydric (wet soil), mesic (moist soil) or xeric (dry soil). The types are not exclusive, but often grade into each other. Unlike many ecosystems of the coastal plain of the southeastern United States, hammocks are not tolerant of fire. Hammocks tend to occur in locations where fire is not common, or where there is some protection from fire in neighboring ecosystems. Hammocks have begun developing in historic times in areas where fire has been suppressed through human intervention, or where elevations above wetlands have been created by dredging, mining, road and causeway building, and other human activities. On the other hand, many hammocks have been destroyed by development, as they often occur on higher land in desirable locations, such as barrier islands and other waterfront locations. The etymology of the term "hammock" is obscure. Dictionaries usually give it as an archaic form of "

hummock In geology, a hummock is a small knoll or mound above ground.Bates, Robert L. and Julia A. Jackson, ed. (1984). “hummock.” Dictionary of Geological Terms, 3rd Ed. New York: Anchor Books. p. 241. They are typically less than in height and ...

" ("hammock" appeared in print earlier than "hummock"). "Hammock" is first attested in English in the 1550s as a nautical term for a tree-covered island (a mound of trees) seen on the horizon. "Hammock" is used to refer to stands of hardwood trees on the coastal plain from

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...

. Types of hammock described in the literature include:

Tropical hardwood hammocks

In the United States, tropical hardwood hammocks are found in southern Florida. Sub-types of hammocks in southern Florida include rockland hammocks on the

Miami Rock Ridge The Miami Rock Ridge is a continuous limestone outcrop which formerly encompassed a large extent of far South Florida, including portions of the Everglades ecosystem. The traditional base of the elevation ranges from northern Miami-Dade County, Fl ...

and in the

Big Cypress National Preserve Big Cypress National Preserve is a United States National Preserve located in South Florida, about 45 miles (72 kilometers) west of Miami on the Atlantic coastal plain. The Big Cypress, along with Big Thicket National Preserve in Texas, becam ...

, Keys rockland hammocks in the Florida Keys, coastal berm hammocks in the Florida Keys and along the north shore of

Florida Bay Florida Bay is the bay located between the southern end of the Florida mainland (the Florida Everglades) and the Florida Keys in the United States. It is a large, shallow estuary that while connected to the Gulf of Mexico, has limited exchange o ...

, tree island hammocks in the

Everglades The Everglades is a natural region of tropical climate, tropical wetlands in the southern portion of the U.S. state of Florida, comprising the southern half of a large drainage basin within the Neotropical realm. The system begins near Orland ...

shell mound A midden (also kitchen midden or shell heap) is an old dump for domestic waste which may consist of animal bone, human excrement, botanical material, mollusc shells, potsherds, lithics (especially debitage), and other artifacts and ecof ...

hammocks, coastal rock barren hammocks in the Florida Keys, and

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

hammocks on the Miami Rock Ridge. The trees forming the

canopy Canopy may refer to: Plants * Canopy (biology), aboveground portion of plant community or crop (including forests) * Canopy (grape), aboveground portion of grapes Religion and ceremonies * Baldachin or canopy of state, typically placed over an ...

of the southernmost tropical hardwood hammocks in Florida are almost all

West Indian A West Indian is a native or inhabitant of the West Indies (the Antilles and the Lucayan Archipelago). For more than 100 years the words ''West Indian'' specifically described natives of the West Indies, but by 1661 Europeans had begun to use it ...

species. The southern live oak (''

Quercus virginiana ''Quercus virginiana'', also known as the southern live oak, is an evergreen oak tree endemic to the Southeastern United States. Though many other species are loosely called live oak, the southern live oak is particularly iconic of the Old Sou ...

'') is the only temperate hardwood species to appear regularly in such hammocks. Hammocks along the east coast of Florida as far north as

Cape Canaveral , image = cape canaveral.jpg , image_size = 300 , caption = View of Cape Canaveral from space in 1991 , map = Florida#USA , map_width = 300 , type =Cape , map_caption = Location in Florida , location ...

, and along the west coast of Florida as far north as the mouth of the

Manatee River The Manatee River is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed April 18, 2011 river in Manatee County, Florida. The river forms in the northeastern corner of Manatee County an ...

Tampa Bay Tampa Bay is a large natural harbor and shallow estuary connected to the Gulf of Mexico on the west-central coast of Florida, comprising Hillsborough Bay, McKay Bay, Old Tampa Bay, Middle Tampa Bay, and Lower Tampa Bay. The largest freshwater ...

, include West Indian species as canopy trees, but with increasing numbers of temperate species with increasing

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...

, so that tropical hardwood hammocks grade into temperate hardwood hammocks. The tree island hammocks in the Everglades appear as teardrop-shaped islands shaped by the flow of water in the middle of the slough. Many tropical species such as mahogany (''

Swietenia mahagoni ''Swietenia mahagoni'', commonly known as American mahogany, Cuban mahogany, small-leaved mahogany, and West Indian mahogany, is a species of ''Swietenia'' native to South Florida in the United States and islands in the Caribbean including the Ba ...

''), gumbo limbo ('' Bursera simaruba''), and cocoplum (''

Chrysobalanus icaco ''Chrysobalanus'' is a genus of evergreen perennial shrubs to small trees, described as a genus by Linnaeus in 1753. It is native to sub-tropical and tropical regions of Africa, Latin America, and Florida Florida is a state located in th ...

'') grow alongside the more familiar temperate species of southern live oak, red maple (''

Acer rubrum ''Acer rubrum'', the red maple, also known as swamp maple, water maple, or soft maple, is one of the most common and widespread deciduous trees of eastern and central North America. The U.S. Forest Service recognizes it as the most abundant nati ...

''), and hackberry (''

Celtis laevigata ''Celtis laevigata'' is a medium-sized tree native to North America. Common names include sugarberry, Southern hackberry, or in the southern U.S. sugar hackberry or just hackberry. Sugarberry is easily confused with common hackberry ('' C. oc ...

'').

Maritime hammocks

Maritime hammocks, also known as maritime forests or coastal hammocks, are found on stable sand dunes away from the beach on

barrier island Barrier islands are coastal landforms and a type of Dune, dune system that are exceptionally flat or lumpy areas of sand that form by wave and tidal action parallel to the mainland coast. They usually occur in chains, consisting of anything fro ...

s, and on small islands in

salt marsh A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is domin ...

es. They are found all along the Atlantic Coast and Gulf Coast of the United States. Some authorities classify coastal hammocks as hydric hammocks.

Temperate hardwood hammocks

Temperate hardwood hammocks are narrow bands of

broadleaf forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...

that occur on the

coastal plain A coastal plain is flat, low-lying land adjacent to a sea coast. A fall line commonly marks the border between a coastal plain and a piedmont area. Some of the largest coastal plains are in Alaska and the southeastern United States. The Gulf Coa ...

of the

. In most of the southeast, including the

Florida panhandle The Florida Panhandle (also West Florida and Northwest Florida) is the northwestern part of the U.S. state of Florida; it is a Salient (geography), salient roughly long and wide, lying between Alabama on the north and the west, Georgia (U. ...

, the trees in temperate hardwood hammocks are primarily

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...

. Hardwood hammocks in northern Florida peninsula have a mixture of deciduous and evergreen trees, and hardwood hammocks in southern Florida north of the Everglades have a mixture of evergreen and tropical trees.

Hydric hammocks

Hydric hammocks, also known as low hammocks, wetland hardwood hammocks, or lowland oak hammocks, grow on soils that are poorly drained or that have high water tables, subject to occasional flooding. They are usually found on gentle slopes just above swamps, marshes or wet prairies. Hydric hammocks are found in scattered locations in Florida north of

Lake Okeechobee Lake Okeechobee (), also known as Florida's Inland Sea, is the largest freshwater lake in the U.S. state of Florida. It is the tenth largest natural freshwater lake among the 50 states of the United States and the second-largest natural freshwa ...

, with concentrations along the upper

St. Johns River The St. Johns River ( es, Río San Juan) is the longest river in the U.S. state of Florida and its most significant one for commercial and recreational use. At long, it flows north and winds through or borders twelve counties. The drop in eleva ...

, the Atlantic coast of northeastern Florida, and particularly along the Big Bend section of the Gulf Coast of Florida, from

Aripeka Ar-pi-uck-i, also known as Abiaka or Sam Jones, (c. 1760 – c. 1860) was a powerful spiritual ''alektca'' ( medicine chief) and war chief of the Miccosukee, a Seminole–Muscogee Creek tribe of the Southeast United States. Ar-pi-uck-i succes ...

to St. Marks.

Mesic hammocks

Mesic hammocks are hammocks of the southeastern United States coasts (from North Carolina to Texas) and all of peninsular Florida which grow on soils that are rarely flooded. The canopy of mesic hammocks consists primarily of evergreen hardwoods and cabbage palms. The southern live oak is the most common tree in mesic hammocks. Other trees commonly found in mesic hammocks include southern magnolia, pignut hickory, water oak, and laurel oak. Some of those trees are less frequent or absent in southern Florida (from about Lake Okeechobee south), where tropical species, such as

gumbo limbo ''Bursera simaruba'', commonly known as gumbo-limbo, copperwood, chaca, West Indian birch, naked Indian, and turpentine tree, is a tree species in the family Burseraceae, native to the Neotropics, from South Florida to Mexico and the Caribbean ...

and satinleaf, may be found. Slash pines and loblolly pines are found in many mesic hammocks. The soil in mesic hammocks is well-drained and rarely flooded, but remains moist due to the shade of the canopy, and the heavy leaf litter that usually occurs in them.

Xeric hammocks

Xeric hammocks, also known as xeric forests or sand hammocks, grow on well-drained sandy soil, such as old sand dunes, where there is some protection from fire. Xeric hammocks are characterized by sand live oak (''

Quercus geminata ''Quercus geminata'', commonly called sand live oak, is an evergreen oak tree native to the coastal regions of the subtropical southeastern United States, along the Atlantic Coast from southern Florida northward to southeastern Virginia and al ...

'') and saw palmetto (''

Serenoa repens ''Serenoa repens'', commonly known as saw palmetto, is the sole species currently classified in the genus ''Serenoa''. It is a small palm, growing to a maximum height around . It is endemic to the subtropical and tropical Southeastern United S ...

''). Xeric hammocks may develop from scrub or

sandhill A sandhill is a type of ecological community or xeric wildfire-maintained ecosystem. It is not the same as a sand dune. It features very short fire return intervals, one to five years. Without fire, sandhills undergo ecological succession and bec ...

communities. Scrub-derived hammocks typically include myrtle oak (''

Quercus myrtifolia ''Quercus myrtifolia'', the myrtle oak, is a North American species of oak. It is native to the southeastern United States (Mississippi, Alabama, Florida, Georgia, South Carolina). It is often found in coastal areas on sandy soils. It is an eve ...

'') and Chapman's oak (''

Quercus chapmanii ''Quercus chapmanii'', commonly referred to as the Chapman oak, is a species of oak that grows in the southeastern United States. Description ''Quercus chapmanii'' is a shrub or small tree occasionally reaching a height of 6 meters (20 feet) bu ...

''), while sandhill-derived hammocks include turkey oak (''

Quercus laevis ''Quercus laevis'', the turkey oak, is a member of the red oak group of oaks. It is native to the southeastern United States. The name turkey oak derives from the resemblance of the leaves to a turkey's foot. A Turkish and southern European sp ...

'') and bluejack oak (''

Quercus incana ''Quercus incana'' is a species of oak known by the common names bluejack oak, upland willow oak, sandjack oak, and cinnamon oak. It is native to the Atlantic and Gulf coastal plains of the United States, from Virginia around Florida to Texas and ...

''). Xeric hammocks require long-term protection from fire to develop, but once established, are somewhat resistant to fire. Sand live oak and myrtle oak reproduce by cloning, and if allowed to become established, may regrow from the roots if the hammock does burns.

Prairie hammocks

Prairie hammocks are a sub-type of hydric and mesic hammocks composed principally of live oak and cabbage palm trees. They occur in central and southern Florida in

prairie Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...

s and

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

s, on river

levee A levee (), dike (American English), dyke (English in the Commonwealth of Nations, Commonwealth English), embankment, floodbank, or stop bank is a structure that is usually soil, earthen and that often runs parallel (geometry), parallel to ...

s, and on slopes between dry uplands and wetlands.

Oak domes

Oak domes, also called oak hammocks, grow as small patches on shallow depressions or slight hills. They consist of thick stands of evergreen oaks, and are distinct from their surrounding habitats, which are typically woodlands dominated by longleaf pine.