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The South Florida rocklands
ecoregion An ecoregion (ecological region) is an ecological and geographic area that exists on multiple different levels, defined by type, quality, and quantity of environmental resources. Ecoregions cover relatively large areas of land or water, and c ...
, in the
tropical and subtropical moist broadleaf forests Tropical and subtropical moist broadleaf forests (TSMF), also known as tropical moist forest, is a subtropical and tropical forest habitat type defined by the World Wide Fund for Nature (WWF). Description TSMF is generally found in la ...
biome A biome () is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate. In 1935, Tansley added the ...
, occurs in southern
Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
and the
Florida Keys The Florida Keys are a coral island, coral cay archipelago off the southern coast of Florida, forming the southernmost part of the continental United States. They begin at the southeastern coast of the Florida peninsula, about south of Miami a ...
in the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
, where they would naturally cover an area of . These forests form on
limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth and other terrestrial planets. Features Outcrops do not cover the majority of the Earth's land surface because in most p ...
s with very thin
soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...
; the higher elevation separating them from other habitats such as coastal
marsh In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...
es and marl prairies. On mainland Florida, rocklands exist primarily on the Miami Rock Ridge, which extends from the Miami River south to
Everglades National Park Everglades National Park is a List of national parks of the United States, national park of the United States that protects the southern twenty percent of the original Everglades in Florida. The park is the largest tropical wilderness in the Un ...
. South Florida rocklands are further divided into pine rocklands and rockland hammocks.


Pine rockland


Description

The pine rocklands are a critically imperiled ecosystem located in
southern Florida South Florida, sometimes colloquially shortened to SoFlo, is the southernmost region of the U.S. state of Florida. It is one of Florida's three most commonly referred to directional regions; the two others are Central Florida and North Florida. S ...
, the
Bahamas The Bahamas, officially the Commonwealth of The Bahamas, is an archipelagic and island country within the Lucayan Archipelago of the Atlantic Ocean. It contains 97 per cent of the archipelago's land area and 88 per cent of its population. ...
,
Turks and Caicos The Turks and Caicos Islands (abbreviated TCI; and ) are a British Overseas Territory consisting of the larger Caicos Islands and smaller Turks Islands, two groups of tropical islands in the Lucayan Archipelago of the Atlantic Ocean and no ...
Islands, and
Cuba Cuba, officially the Republic of Cuba, is an island country, comprising the island of Cuba (largest island), Isla de la Juventud, and List of islands of Cuba, 4,195 islands, islets and cays surrounding the main island. It is located where the ...
. Its location in south Florida and throughout the Caribbean Archipelago straddles the southern and northern ends of the
temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...
and
tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...
flora ranges, respectively. This helps explain why the pine rocklands are home to a wide variety of plants and animals, many of which are
endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
to Florida, south Florida, or the pine rockland itself. It is characterized by an open
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 a ...
of South Florida slash pine ('' Pinus elliotti var. densa''), a patchy subcanopy of palms and shrubs, and an extremely diverse
herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...
layer, growing atop Miami oolitic limestone. Historically, the landscape was maintained by frequent low-intensity fires, but
urbanization Urbanization (or urbanisation in British English) is the population shift from Rural area, rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. ...
,
agricultural expansion Agricultural expansion describes the growth of agricultural land ( arable land, pastures, etc.) especially in the 20th and 21st centuries. The agricultural expansion is often explained as a direct consequence of the global increase in food and e ...
, exotic invasion and fragmentation have led to
fire suppression Fire suppression may refer to: * Firefighting * Fire suppression systems * Wildfire suppression Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts depend on many factors such as the availabl ...
and severe changes in plant community composition.


Distribution

In south Florida, pine rocklands occur in
Miami-Dade County Miami-Dade County () is a county located in the southeastern part of the U.S. state of Florida. The county had a population of 2,701,767 as of the 2020 census, making it the most populous county in Florida and the seventh-most-populous coun ...
, Monroe County, the Lower Keys,
Everglades National Park Everglades National Park is a List of national parks of the United States, national park of the United States that protects the southern twenty percent of the original Everglades in Florida. The park is the largest tropical wilderness in the Un ...
, and
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, beca ...
, but can also be found throughout the Caribbean Archipelago. Despite its range, the pine rocklands are limited in distribution. Urban development, agricultural expansion, and extreme fragmentation since the late 1800s have severely reduced the extent of its range. Of the original estimated 65,450 ha of Miami-Dade County pine rockland, around 920 ha, or 2%, remain outside of
Everglades National Park Everglades National Park is a List of national parks of the United States, national park of the United States that protects the southern twenty percent of the original Everglades in Florida. The park is the largest tropical wilderness in the Un ...
. The remaining fragments scattered across the county are protected as public parks or Environmentally Endangered Lands and range in size from 0.1 ha to 324 ha, with the average size being 6 ha and the median being 1.7 ha. The Long Pine Key portion in Everglades National Park still holds around 9915 ha, or 80% of all pine rockland found in Florida. Limited reserves found in the Lower Keys are decreasing due to
fire suppression Fire suppression may refer to: * Firefighting * Fire suppression systems * Wildfire suppression Wildfire suppression is a range of firefighting tactics used to suppress wildfires. Firefighting efforts depend on many factors such as the availabl ...
and salt-water intrusion via
rising sea levels The sea level has been rising from the end of the last ice age, which was around 20,000 years ago. Between 1901 and 2018, the average sea level rose by , with an increase of per year since the 1970s. This was faster than the sea level had e ...
.


Physiography

The pine rocklands in Miami-Dade County and Everglades National Park are found on
limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
substrates along the Miami Rock Ridge, an exposed
oolitic limestone Oolite or oölite () is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. Strictly, oolites consist of ooids of diameter 0.25–2 millimetres; rocks composed of ooids larger than 2 mm are called pisol ...
matrix 2–7 meters above sea level that extends from northern Miami to the southern Everglades with disjunct sections in the Lower Keys. This limestone is extremely sharp, porous, and prone to weathering and dissolution and which help form their characteristic solution holes. These holes can house water, sand, or organic soil, and contribute to small changes in elevation that result in substantial changes in vegetation. Interlaced with the limestone ridge are lower elevation wet prairies and
marsh In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...
es and higher elevation rock hammocks. These wet prairies and marshes create an island-like effect isolating the higher elevated pine rocklands. This interaction between elevation and water is particularly evident in Long Pine Key in Everglades National Park. Sections of Long Pine Key flood anywhere from 20 to 60 days per year. However, the hydrology of south Florida has changed drastically since the 1950s due to urban expansion and increased agricultural practices. The limestone of the Miami Rock Ridge was perfect for development, and subsequent drainage has led to a significant decrease in the water table. A lowered water table may harm sites prone to seasonal flooding and may increase the risk of salt-water intrusion. The Comprehensive Everglades Restoration Plan is an attempt to restore the hydrology of the Everglades.


Flora

The south Florida pine rockland is unique geographically. Southern Florida is located at the southern end of the temperate North American Floristic Region and at the northern end of the tropical Caribbean Floristic Region. This location allows for the mixture of vegetation from two distinct areas at the extremes of their ranges.  Around 9% of all pine rockland plants found in Miami-Dade County alone are endemic to Florida, and around 14 taxa are endemic to the Miami-Dade pine rockland itself. Overall, there are over 537 plant species found throughout the south Florida rocklands. Pine rocklands are defined by an open canopy of South Florida slash pine with heights ranging from 20–24 meters, but can be less due to past disturbance. Seedlings are fire adapted and spend 2 to 5 years in the "grass stage" building nutrient reserves to facilitate growth above normal fire heights. Many sites were logged extensively in the early 1990s reducing slash pine coverage and killing understory vegetation. Subsequent plantings in the late 1980s led to many even-aged stands with different stand densities. The subcanopy is dominated by a variety of palms and tropical hardwoods, depending on the location, substrate, and fire regime. Pine rocklands in the lower Keys often have high amounts of '' Thrinax'' and '' Coccothrinax'', while rocklands in Miami-Dade County have high amounts of ''
Sabal palmetto ''Sabal palmetto'' (, ''Help:Pronunciation respelling key, SAY-bəl''), also known as cabbage palm, cabbage palmetto, sabal palm, blue palmetto, Carolina palmetto, common palmetto, Garfield's tree, and swamp cabbage, is one of 15 species of Saba ...
'', '' Ficus aurea'', and ''
Serenoa repens ''Serenoa repens'', commonly known as saw palmetto, is a small palm, growing to a maximum height around . Taxonomy It is the sole species in the genus ''Serenoa''. The genus name honors American botanist Sereno Watson. Distribution and ...
''. Sites that share borders with hardwood hammocks or that are infrequently burned will have high amounts of hardwood species, including ''
Metopium toxiferum ''Metopium toxiferum'', the poisonwood, Florida poisontree, coral sumac, or hog gum, is a species of flowering tree in the cashew or sumac family, Anacardiaceae, that is native to the American Neotropics. It produces the irritant urushiol muc ...
'', ''Quercus elliotti'', ''
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 South. ...
'', '' Sideroxylon salicifolium'', and '' Lysiloma latisiliquum''. The shrub layer near wet prairies and marshes is composed of wetland species such as ''Acacia pinetorum'', ''
Sambucus canadensis ''Sambucus canadensis'', the American black elderberry, Canada elderberry, or common elderberry, is a North American species of elderberry. Description It is a deciduous suckering shrub growing to tall. The leaves are arranged in opposite pairs ...
'', and ''
Taxodium ascendens ''Taxodium ascendens'', also known as pond cypress, is a deciduous conifer of the genus ''Taxodium'', native to North America. Many botanists treat it as a variety of bald cypress, ''Taxodium distichum'' (as ''T. distichum'' var. ''imbricatum'') ...
''. The herbaceous layer is extremely diverse and home to several species considered rare, endangered, threatened or critically imperiled by one or more agencies. Many species found in rocklands throughout south Florida are restricted to individual plots or to specific regions due to changes in soil type, extreme fragmentation, and fire suppression. Most plants are fire-adapted and depend on frequent burning to limit shading and increased humidity from encroaching hardwood species. Grasses and sedges including ''Andropogon spp.'', ''Schizachyrium spp.'', '' Muhlenbergia capillaris'', ''Arsitida purpurascens'', and ''Rhynchospora spp.'' dominate the landscape. Flowering species include ''Croton linearis'', ''Pinguicula pumilla'', '' Angadenia berteroi'', ''Amorpha herbacea var. crenulate'', and a number of different '' Euphorbia spp''.


Fire

Fire plays a critical role in maintaining the vegetative community. It is estimated that around 70% of the state's terrestrial plant species are fired-adapted, fire-dependent, or pyrogenic, probably resulting from the state's high incidence of lightning strikes. In fact, the Florida landscape is estimated to have been dominated by dry season lightning-induced and human-ignited fires. Most of the native plant species found in pine rocklands are adapted to periodic fires, with increased abundance and flowering of native plants found in plots post-burn. These fires help curb hardwood encroachment, spur pine regeneration, and allow light to reach the herbaceous layer. In the absence of fire, hardwood species from nearby hardwood hammocks invade and shade out natural vegetation. As the density of hardwood species increases, fire effectiveness decreases due to the increase in humidity and accumulation of poor fire fuels. This ecotone between pine rockland and hardwood hammock is clear when natural or frequent, low-intensity prescribed fires occur. In the absence of frequent fire, this distinction becomes less apparent. Presently, many isolated pine rockland sites throughout Miami-Dade County and the lower Keys suffer from fire suppression, leading to drastically altered plant compositions. It is estimated that around 5,000,000 ha of pine rocklands burned in 1926, whereas only 76,486 ha burned in 1995 and 2003. Most sites located in Miami-Dade County and the lower Keys are located near residential or commercial lots and are often unable to implement prescribed burns. The longer fire is suppressed, the harder and more dangerous it is to prescribe effective burns. Fuel loads increase between fires and result in hotter and higher flames. Fires that are too high or intense can result in crown fire or mortality at all levels of the canopy, including below ground biomass. Frequent fire is used to great effect in the Long Pine Key in Everglades National Park.


Rockland hammock

Rockland hammocks form on regions of rockland where a lack of fire has allowed
hardwood Hardwood is wood from Flowering plant, angiosperm trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal ecosystem, boreal latitudes they are mostly deciduous, but in tropics and subtropics mostl ...
trees to become dominant, nearly all of which are tropical in origin. Natural
firebreak A firebreak or double track (also called a fire line, fuel break, fireroad and firetrail in Australia) is a gap in vegetation or other combustible material that acts as a barrier to slow or stop the progress of a bushfire or wildfire. A firebre ...
s include exposed
limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
cliff In geography and geology, a cliff or rock face is an area of Rock (geology), rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. ...
s and solution
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 also known as shakeholes, and to openings where surface water ...
s.
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 a ...
species include gumbo-limbo (''
Bursera simaruba ''Bursera simaruba'', commonly known as gumbo-limbo, the tourist tree, copperwood, almácigo, chaca, West Indian birch, naked Indian, and turpentine tree, is a tree species in the family Burseraceae, native to the Neotropics, from South Florid ...
''), paradise tree (''
Simarouba glauca ''Simarouba glauca'' is a Flowering plant, flowering tree that is native to Florida, South America, and the Caribbean. Common names include paradise-tree, dysentery-bark, and bitterwood. The tree is well suited for warm, humid, tropical regions. ...
''), pigeonplum ('' Coccoloba diversifolia''), Florida strangler fig ('' Ficus aurea''), false mastic ('' Sideroxylon foetidissimum''), willow bustic (''
Dipholis salicifolia ''Sideroxylon salicifolium'', commonly called white bully or willow bustic, is a species of flowering plant native to Florida, the West Indies and Central America. Taxonomy It has also been considered a member of the genus '' Dipholis'', with ...
''), short-leaf fig ('' Ficus citrifolia''), false tamarind ('' Lysiloma latisiliquum''), West Indian 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 the broader Caribbean bioregion. It is the species from which the original mahog ...
''), and pepperleaf sweetwood ('' Licaria triandra'').
Epiphyte An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...
s that grow in the canopy include
Spanish moss Spanish moss (''Tillandsia usneoides'') is an Epiphyte, epiphytic flowering plant that often grows upon large trees in tropical and subtropical climates. It is native to much of Mexico, Bermuda, the Bahamas, Central America, South America (as far ...
(''Tillandsia usneoides'') and ball moss ('' T. recurvata''). Plants such as black ironwood ('' Krugiodendron ferreum''), inkwood ('' Exothea paniculata''), lancewood ('' Damburneya coriacea''), marlberry ('' Ardisia escallonoides''), poisonwood (''
Metopium toxiferum ''Metopium toxiferum'', the poisonwood, Florida poisontree, coral sumac, or hog gum, is a species of flowering tree in the cashew or sumac family, Anacardiaceae, that is native to the American Neotropics. It produces the irritant urushiol muc ...
''), satinleaf (''
Chrysophyllum oliviforme ''Chrysophyllum oliviforme'', commonly known as the satinleaf, is a medium-sized tree native to Florida, the Bahamas, the Greater Antilles, and Belize. It is also known as damson plum, wild star-apple and saffron-tree. It gets the name "satinleaf ...
''), white stopper (''
Eugenia ''Eugenia'' is a genus of flowering plants in the myrtle family Myrtaceae. It has a worldwide, although highly uneven, distribution in tropical and subtropical regions. The bulk of the approximately 1,100 species occur in the New World tropics, ...
axillaris''), shiny oysterwood ('' Gymnanthes lucida''), wild coffee (
Psychotria nervosa ''Psychotria nervosa'', also known as Seminole balsamo or wild coffee, is a shade tolerant medium-sized shrub native to Florida as well as the West Indies and Central and South America. It produces a "small, red, ellipsoid fruit" that resembles ...
), shortleaf wild coffee ( Psychotria tenuifolia), and pale lidflower ('' Calyptranthes pallens'') grow in the
understory In forestry and ecology, understory (American English), or understorey (English in the Commonwealth of Nations, Commonwealth English), also known as underbrush or undergrowth, includes plant life growing beneath the Canopy (biology), forest ca ...
. 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 South. ...
''), a
temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...
species, can be found on hammock margins.


Conservation

Because of its high elevation, the Miami Rock Ridge was the first area to be impacted by development. The clearing of large tracts for development has now reduced the pine rocklands to about , most of which are now protected inside the
Everglades National Park Everglades National Park is a List of national parks of the United States, national park of the United States that protects the southern twenty percent of the original Everglades in Florida. The park is the largest tropical wilderness in the Un ...
. Camp Everglades is a campground owned by the Boy Scouts and located within the park. The pine forest is fire dependent, and the flora and fauna have adapted to the frequent fires ignited by summer lightning storms. The camp has prescribed fires that help maintain the forest.


See also

* List of ecoregions in the United States (WWF) *
Bahamian dry forests The Bahamian dry forests are a tropical and subtropical dry broadleaf forest ecoregion in the Bahamas and the Turks and Caicos Islands, covering an area of . They are found on much of the northern Bahamas, including Andros, Abaco, and Grand B ...
* Bahamian pineyards * Pine barren


References

{{reflist Tropical and subtropical moist broadleaf forests of the United States Ecoregions of Florida * Forests of Florida Neotropical tropical and subtropical moist broadleaf forests