Tropical hardwood hammock
Tropical hardwood hammocks are closed canopy forests, dominated by a diverse assemblage of evergreen and semi-deciduous tree and shrub species, mostly of West Indian origin.
Significant work has been initiated to restore existing disturbed tropical hardwood hammocks and to control exotic plant species.
Tropical hardwood hammock is a closed canopy forest, dominated by a diverse assemblage of evergreen and semi-deciduous tree and shrub species, mostly of West Indian origin.
Soils in tropical hardwood hammocks are primarily composed of organic material which has accumulated directly on top of mineral substrate, and are moist but rarely inundated.
[4] Upland coastal rock barrens are openings on flat rocklands with sparse, mostly low-growing xeric plants and exposed limestone.
Mesic conditions are developed by a combination of the hammock's rounded profile and nearly impenetrable edges, which deflect wind and limit the effects of desiccation.
The dense canopy minimizes temperature fluctuations by reducing soil warming during the day and heat loss during the night.
Coastal rock barrens are found on flat rocky surfaces either immediately adjacent to the coast or within the interior of islands in the Florida Keys.
Soils, when they exist, consist of calcareous marls and organic debris on the surface, within solution depressions, and in crevices in limestone.
Miami Rock Ridge hammocks are also important habitat for a number of listed epiphytic orchids, bromeliads, ferns, and peperomias found in the Big Cypress and other regions.
[10] When the organic layer is not consumed, recovery of tropical hardwood trees is rapid, and canopy closure can be achieved in 40 years or less.
[citation needed] The majority of the remaining tropical hardwood hammocks outside of the Florida Keys have now been acquired and are no longer threatened by development.
The small number and size, five sites totaling 4.5 ha (11 acres) of these unique areas, makes them susceptible to development impacts and invasion by exotic plants.
In the upper Florida Keys, virtually all of the tropical hardwood hammock is secondary growth, because of earlier conversions to agriculture.
Although tropical hardwood hammocks tend to be located in patches across the landscape, they compose part of a complex mosaic of communities including mangroves, coastal marshes and prairies, freshwater swamps, and pinelands.
For instance, the physical separation of Key Largo woodrats caused by hammock fragmentation makes it more difficult for them to locate a mate.
The development of roads has increased access to natural areas, including hammocks, to collectors of orchids, bromeliads, ferns, butterflies, and Liguus tree snails.
Vines, such as Gold Coast jasmine (Jasminum dichotomum), air-potato (Dioscorea bulbifera), and nephthytis (Syngonium podophyllum), have decimated many hammocks on the Miami Rock Ridge.
Exotic trees and shrubs such as Brazilian pepper (Schinus terebinthifolius) are problematic in hammocks throughout South Florida, including undisturbed areas in the Everglades.
Coastal berm hammocks along the shores of Florida Bay have been heavily impacted by the sprawling vine-like shrub latherleaf (Colubrina asiatica).
Hurricanes and other disturbance phenomena, which are natural parts of the South Florida ecosystem, can also have negative effects once fragmentation and the spread of exotic plant species have occurred.
In both Miami-Dade County and the Florida Keys, cooperation with landowners of tropical hardwood hammocks is essential to the long-term protection of this natural community.
In 1979, Dade County enacted the Environmentally Endangered Lands Covenant Program which reduces taxes for owners of tropical hardwood hammocks and pine rocklands who agree not to develop these systems and to manage them for a period of 10 years.
No similar system exists in Monroe County, where a significant amount of tropical hardwood hammock is still in private ownership, and much is subdivided into small parcels.
The most aggressive campaign to restore tropical hardwood hammocks is being conducted by Miami-Dade County Parks and Recreation Department, Natural Areas Management Division.
Monitoring of this program at three hammocks has been conducted by the University of Miami, and ongoing technical assistance has been provided by the Institute for Regional Conservation.
The Natural Areas Management Division has also provided technical assistance and training to the City of Miami for the restoration of tropical hardwood hammocks there.
A testament to this is the fact that virtually all of the tropical hardwood hammocks in the Florida Keys are secondary and have recovered following clearing for agriculture and settlements.
[20] One of the downsides of the trend in landscaping with native plants is that some species are being distributed outside of their historic range, where they can become established and potentially invasive.
