South Florida Rocklands

Most of the upland areas of extreme south Florida are associated with outcroppings of limestone.  Pinelands and tropical hardwood hammocks cover virtually all of these outcrops and are the rockland ecosystems introduced here. 

The area covered by rockland ecosystems is relatively small and shrinking because of the pressure of urban development.  Land required by the expanding population of the greater Miami area and the Florida Keys has been obtained largely by clearing pinelands and hammocks. 

Surface Geology & Location

South Florida rockland outcrops are primarily marine limestone and occur in three distinct geographical regions: 

  • The Miami rock ridge is located from Miami to the town of Homestead - This is the largest outcrop;
  • the upper and lower Florida Keys; and
  • the southeast corner of Big Cypress Swamp

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Land Use & Conservation

Many hammocks and pinelands have been cleared for agriculture and urban development, but several are protected on various federal, state, and local government lands.

Protected Hammocks

tropical hardwood hammock, photo by Julie Anne Ferguson Demers

Despite the loss of large important forests in Dade county, more than half of the tropical hardwood hammocks that were there at the beginning of settlement still exist.  Several hammocks are owned by Dade county and most of the remaining undeveloped hammocks have been proposed for purchase by the state's Conservation and Recreation Lands (CARL) program. 

Most hardwood hammocks on the Florida Keys are privately owned and are not protected against clearing.  Demand for commercial and residential development on the Keys is such that all privately held land is almost certain to be cleared eventually. 

A few large tracts of hammocks are protected by the federal government

  • Biscayne National Park in the upper Keys
  • The National Key Deer Refuge in the lower Keys

Two major land acquisition programs are underway on Key Largo:

  • The Crocodile Lakes National Wildlife Refuge of the U.S. Fish and Wildlife Service, and
  • The North Key Largo Hammock Preserve of the Florida Department of Natural Resources.

These will add substantially to the total area of protected rocklands in the Keys.

Protected Pinelands

Pineland areas have been much more devastated than have the hardwood hammocks.  Aside from Long Pine Key in Everglades National Park, the only large areas of Pineland are: 

  • Navy Wells Pineland Preserve owned by Dade County
  • Pinelands on the Deering Estate at Cutler owned by Dade County
  • Pinelands around Richmond Air Field owned by several government agencies

The largest of the remaining pinelands have been proposed for purchase by the CARL program.  However, passive protection is not sufficient to preserve the pineland ecosystem. 

They must be burned regularly and the small size of the remaining pinelands combined with the presence of residential and commercial development greatly restrict burning  programs. 

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Exotic Plants

Exotic plants present a major threat to hammocks, pinelands and other ecosystems throughout south Florida.  Several trees planted as ornamentals in south Florida invade plant communities and displace native species.  Threatening exotic plants include:

  • Schinus terebinthifolius (Brazilian pepper) - this plant is the worst invader of infrequently burned pinelands.
  • Bischofia javanica
  • Schefflera actinophylla
  • Colubrina asiatica - a woody vine which smothers hammocks in coastal areas
  • Syngonium - a herbaceous vine
  • Sansevieria - a ground-covering herbaceous plant
  • Melaleuca quinquenervia - this tree is a major threat to the south Florida rocklands ecosystems within the boundaries of the Big Cypress Preserve and to other ecosystems throughout south Florida.

Active management is necessary to control these exotics!!

For more information about these and other invasive exotic plants in Florida, visit the Florida Exotic Pest Plant Council Web site.

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Rockland Ecosystems

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