South Florida

South Florida is distinct from most of the US.  It is noticeably more “tropical” than northern and central Florida.  Florida does not actually extend into the tropics (which is about 23.4369 degrees (about 23˚ 26′) North latitude; the southernmost part of the Florida Keys is about one degree north of this.  However, the close proximity of warm oceans to most of Florida results in a climate that is comparable to many humid tropical locations.

The scarcity of frost and relatively high rainfall has resulted in many tropical plants and animals being found, in the US, only in southern Florida.  For example, there are 12 palms native to Florida, but six of these are only found south of Lake Okeechobee and three are only found in the Keys (they are more common throughout the Caribbean).  A similar situation exists with regards to epiphytic plants (those that grow on trees for support).  Although a very few epiphytic bromeliads and orchids exist in northern Florida, their diversity increases rapidly as one proceeds south.  A maximum diversity is found in the hardwood hammocks in south Florida.  These hammocks are relatively dry “islands” a few feet above the saturated conditions found in much of the Everglades and support many hardwood trees).  Conditions within these hammocks can be warmer than outside, and thus more protective against wind and freezing temperatures during the coldest winter nights.  In south Florida there are many epiphytic orchids and 16 epiphytic bromeliad species.  Note that an excellent source of information about wildlife and vegetation of Florida is the University of Florida extension site here.  Another University of Florida site that is excellent in describing South Florida’s aquatic environments (almost everything!) is here.  And for plants, almost nothing is better than the Florida Plant Atlas (for the botanically inclined).

When looking at a tree festooned with epiphytes you should recognize that most of these are bromeliads, not orchids.  At least in Florida, most of the epiphyte biomass is associated with bromeliads.  Orchids tend to be more inconspicuous and smaller.

Curiously, despite the warmer climate in southern Florida, there is actually less diversity of reptiles and amphibians, mammals, and most other organisms than in northern Florida.  This is because there is less topographic diversity, and thus fewer distinct environments, than farther north.  There are no shaded north-facing canyon slopes, or sunny south-facing hillsides, in south Florida.  No floodplains covered in silt and little to no diversity of the underlying rock (not that there is anywhere in Florida, but farther north there is).  The oceanic barriers also reduce migration into south Florida relative to north Florida.

Despite the previous paragraph’s assertion that South Florida is not very diverse overall, there is a major (unfortunate) exception.  South Florida probably has the greatest number of non-native, introduced species of anywhere in the US.  The pet and horticultural trades have resulted in many tropical species becoming invasive in south Florida.  These include Burmese Pythons, Walking Catfish, parrots and such, and many invasive plant species, including Melaleuca species from Australia.

Essential Reading for visitors to the Everglades National Park is the ebook version of a National Park Service Guide published in 1988.  The diagrams and descriptions are still valid however and it will provide a more concise understanding of the Everglades than perhaps any other single source.  Another, less detailed source of information is the Wikipedia article focusing on the geography and ecology of the Everglades.

Best locations for seeing larger wading birds like Herons etc

Herons, Egrets, Ibises and such can be seen anywhere in Florida and the locations mentioned below are not by any means the best at any particular time.  A roadside ditch might give you spectacular view at any moment.  But the following places have facilities for sustained observation or photography of birds and other wetland organisms, unlike the side of a highway.  Locations in the Everglades NP have the usual NP entrance fees, while Corkscrew Swamp is an Audubon Preserve and charges admission.

Anhinga Trail, Everglades National Park

Shark Valley, Everglades National Park

Six Mile Cypress Slough Preserve

Corkscrew Swamp Preserve

Kirby Storter Roadside Park

 

Hardwood Hammocks

These are patches of mostly tropical, mostly-evengreen trees and shrubs that exist on slightly higher patchs of land within the Everglades and peripheral areas.  The term is loosly used, so that any primarily hardwood (as opposed to softwood (pine) forest patch – even in central or northern Florida.  These patches stand out against the surround Everglades sawgrass community in far southern Florida and here reside many frost-sensitive plants.  During extreme cold events the hammocks will be  warmer than the surrounding open areas and will also not be exposed to the cooling wind.  They thus act as a reservoir for plants that cannot take frost.

An example of hardwood hammocks is shown in this image.  In the everglades, these islands are elongated along the direction of water flow – a result of dissolution of the limestone islands by the slowly flowing water surrounding them.

 

Sawgrass community

 

Coastal Ridge Pine Forests

 

Cypress Heads  These are circular areas of Baldcypress trees that appear to extend above the surrounding terrain – that is usually sawgrass.  However, these “heads” are actually depressions that usually contain water except in serious droughts.  The structure of these heads can be seen from Google Earth imagery or an idealized cross section is here.

 

 

Unique flora in South Florida

Epiphytes

Epiphytes are particularly abundant in south Florida.   Most older trees in residential areas are festooned with epiphytes, though some species are more favored than others..  Live oaks tend to be heavily festooned with Tillandsia, while Pines are not.  Some Tillandsia species dominant the total biomass of epiphytes, while others are somewhat uncommon.  Many orchids can be very uncommon, and in general probably 90% or more of the epiphyte biomass are Tillandsia species.

While some Tillandsia species can be seen on almost any mature oak tree in the Miami area, others are uncommon and require knowing what to look for and where.   For orchids, the Fakahatchee Strand and the Corkscrew Swamp are well-known, though closely approaching closely many orchids is difficult from a boardwalk -either because those within arms-reach may have been collected or others may be high up on trees.   Sometimes is is best to use rubber boots and wade into a “cypress head” to be able to closely examine and photograph epiphytes.

Palms

Seeing the native Florida palms in habitat requires first knowing which ones are really native to Florida (since so many have been introduced), and then knowing where to see them.  Trails in the Everglades National Park allow views of the Roystonea and Paurotis palms that are otherwise hard to see in the wild (though Roystonea are very widely planted in south Florida).  In the Florida Keys one can see the Thrinax and Pseudothrinax palms on nature trails on Big Pine Key and elsewhere.

Mangroves

Mangroves are plants that live along the coast and are adapted to living in salt water.  They have special glands that excrete salt so that their tissues remain relatively less saline than the seawater.  There are three mangrove species found in the US (and only four or so species in the entire Western Hemisphere – compared with thirty or more species in southeast Asia).  While mangroves extend almost to northern Florida and are also found in south Texas, they are most extensive in southern Florida.  The Red Mangrove (Rhizophora mangle) is the most stereotypical of the mangroves, with its large “prop roots”.  The Black Mangrove (Avicennia germanens) has pneumatophores that stick vertically out of the mud where they grow, and the White Mangrove (Laguncularia species) is relatively inconspicuous by comparison.  Mangroves show a distinct zonation, with the Red Mangroves closest to the open ocean, followed by the more salt tolerant Black Mangroves.  Good descriptions of the mangrove species found in south Florida, together with their adaptations and other aspects is at the University of Florida Museum’s website.  Also see the Wikipedia site here.  The reasons behind mangrove zonation, related to differing salinity tolerance,  are described here.

However, even these links don’t quite explain why the salinity varies across the mangrove zone, and this has to do with salt being deposited during rare high tides at the upper reaches of the mangrove zone.  In drier climates this salt is not washed away and accumulated with each successive high tide until only salt flats remain where few if any plants can grow.  These can be seen clearly on satellite images.  Because of Florida’s higher rainfall, these salt flats are not as obvious as in drier areas of the world.  But the zonation is obvious on the ground, especially in the Florida Keys (drier than mainland Florida).

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