Hammock (ecology)
Hammock is a term used in the
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.[1]
The etymology of the term "hammock" is obscure. Dictionaries usually give it as an archaic form of "hummock" ("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 to Mississippi.[2][3][4] 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
The trees forming the canopy of the southernmost tropical hardwood hammocks in Florida are almost all West Indian species. The southern live oak (Quercus virginiana) 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, and along the west coast of Florida as far north as the mouth of the Manatee River on Tampa Bay, include West Indian species as canopy trees, but with increasing numbers of temperate species with increasing latitude, so that tropical hardwood hammocks grade into temperate hardwood hammocks.[1]
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), gumbo limbo (Bursera simaruba), and cocoplum (Chrysobalanus icaco) grow alongside the more familiar temperate species of southern live oak, red maple (Acer rubrum), and hackberry (Celtis laevigata).[6]
Maritime hammocks
Maritime hammocks, also known as maritime forests or coastal hammocks, are found on stable sand dunes away from the beach on barrier islands, and on small islands in salt marshes. They are found all along the Atlantic Coast and Gulf Coast of the United States. Some authorities classify coastal hammocks as hydric hammocks.[7][8][9][10]
Temperate hardwood hammocks
Temperate hardwood hammocks are narrow bands of
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, with concentrations along the upper St. Johns River, the Atlantic coast of northeastern Florida, and particularly along the Big Bend section of the Gulf Coast of Florida, from Aripeka to St. Marks.[14]
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
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 (
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 prairies and floodplains, on river levees, and on slopes between dry uplands and wetlands.[21]
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.[22]
See also
Notes
- ^ a b "Tropical Hardwood Hammock". Miami-Dade County. Retrieved 25 December 2011.
- ^ Austin, Daniel F. (February 1983). "Hammocks" (PDF). Palmetto. 3 (1): 4. Retrieved 25 December 2011.
- PMID 17772542.
- ^ Vince, Susan W.; Humphrey, Stephen R.; Simmons, Robert W. (September 1989). The Ecology of Hrdric Hammocks (PDF). Biological Report. Washington, D.C.: U.S. Department of the Interior Fish and Wildlife Service. p. 4. Retrieved December 12, 2018.
- ^ "Tropical Hardwood Hammock". Croc Docs - University of Florida Research and Education Center. Retrieved 24 December 2011.
- ^ "Ecosystems: Hardwood Hammock". National Park Service. Retrieved 24 December 2011.
- ^ "Maritime Hammock Habitats". Smithsonian Institution. Retrieved 24 December 2011.
- ^ Fabrizio, Laura and Maria S. Calvi (2003). "Georgia's Marsh Hammocks: A biological survey" (PDF). Southern Environmental Law Center. p. 5. Archived from the original (PDF) on 26 April 2012. Retrieved 24 December 2011.
- ^ "Marsh Environments: Coastal Hammocks, Oyster Bars, and Salt Barrens". United States Geological Survey. Retrieved 24 December 2011.
- ^ "Florida Ecological Restoration Inventory - Hardwood Hammocks and Forests". Florida Department of Environmental Protection. Retrieved 2 January 2012.
- ISBN 978-1-56164-361-5.
- ISBN 978-1-56164-308-0. Retrieved 24 December 2011.)
{{cite book}}
: CS1 maint: multiple names: authors list (link - ^ "Temperate Hardwood Forests". University of Florida IFAS Extension. Retrieved 24 December 2011.
- ^ Vince, Susan W.; Humphrey, Stephen R.; Simmons, Robert W. (September 1989). The Ecology of Hrdric Hammocks (PDF). Biological Report. Washington, D.C.: U.S. Department of the Interior Fish and Wildlife Service. pp. 1–3. Retrieved December 12, 2018.
- ^ "Mesic Temperate Hammock". Croc Docs - University of Florida Research and Education Center. Retrieved 24 December 2011.
- ^ "Hardwood Hammock Forest" (PDF). Florida Fish and Wildlife Conservation Commission. Retrieved 2 January 2012.
- ^ "Mesic Hammock" (PDF). Florida Natural Areas Inventory. Retrieved 16 June 2018.
- ^ "Xeric Hammock" (PDF). Florida Natural Areas Inventory. Retrieved 31 December 2011.
- ^ "Xeric Hammock". University of Florida: Ordway-Swisher Biological Station. Archived from the original on 26 April 2012. Retrieved 31 December 2011.
- ^ "Woodland Habitat: Xeric Hammocks". Friends of the Enchanted Forest. Retrieved 31 December 2011.
- ^ "Mesic Hammock" (PDF). FNAI. Retrieved 16 June 2018.
- ^ "Southern Coastal Plain Oak Dome and Hammock". NatureServe Explorer. Retrieved 17 January 2013.
Further reading
- An Ecological Characterization of Coastal Hammock Islands in South Carolina - Site accessed June 18, 2018