KUCHLER TYPE DESCRIPTION
Kuchler Type: Subtropical Pine Forest


PHYSIOGRAPHY : 
Southern Florida is noted for its lack of topographic relief; very
slight changes in elevation have a pronounced effect on hydroperiod and
therefore on soils and vegetation.  Rock ridge pinelands are only a few
centimeters to several meters higher than surrounding wetlands [32].

Subtropical pine forest occurs in the Miami Rock Ridge region on
outcrops of Miami oolitic limestone.  This formation has a maximum
elevation of 20 feet (6 m) near Miami, and a maximum elevation of
approximately 9 feet (3 m) near Homestead, and is 1.5 to 2 feet (.6 m)
above mean sea level in the Everglades [6].


CLIMATE : 
Southern Florida has a subtropical, humid climate with distinct wet and
dry seasons; 75 percent of the annual precipitation falls during the wet
season, from April to October [32].  Annual rainfall in Big Cypress
Swamp averages around 60 inches (1,524 mm) and ranges from 35 to 80
inches (889-2,032 mm) [40].  In Everglades National Park, annual
rainfall ranges from 30 to 100 inches (760-2,540 mm) [39].  The northern
portions of the Miami Rock Ridge receive 60 to 65 inches (1,525-1,650
mm) per year.  The amount of rainfall decreases gradually to the south
and west:  Pinecrest (southern Big Cypress Swamp) and southern Miami
Rock Ridge receive 55 to 60 inches (1,400-1,525 mm) annually and the
upper Keys receive 40 to 45 inches (1,015-1,145 mm) per year [33].
Temperatures are fairly uniform across southern Florida; the July
average is 81 degrees Fahrenheit (27 deg C) near Pinecrest and 84
degrees Fahrenheit (29 deg C) in the Keys.  Freezes are possible any
year in the Miami Rock Ridge area but are rare [33].

Southern Florida has more thunderstorm days per year (70-90) than any
other region in the United States.  Over 6,000 cloud-to-ground lightning
strikes were recorded in a single afternoon in southern Florida.
Lightning killed pines are a common sight throughout the slash pine
(Pinus elliottii) belt [42].


SOILS : 
Subtropical pine forest occurs on a range of substrates, from
well-drained, porous soils with little exposed rock to mostly exposed
rock (primarily oolitic limestones) [6,24].  Soil development is minimal
[24].  Where fire has removed litter and understory vegetation there is
usually very little organic matter left; sometimes the surface is mostly
bare rock [33].  The solubility of limestone substrates produces some
unusual microtopography.  Small [47] described the surface of the Long
Pine Key area as consisting chiefly of holes [30].  Pinnacle rock is a
common feature:  Pillars of limestone are left between subterranean flow
chambers from which the rock shell has collapsed.  Dogtooth limestone is
formed where surface rock is riddled by small holes with steep, sharp
sides [33].  Solution holes in the underlying rock are filled with sand,
marl or peat and constitute the majority of the available rooting medium
[6].  These substrates are often 30 to 50 percent organic matter.  The
nutrient-poor soils are usually neutral or slightly alkaline, but
occasionally shallow depressions contain fine, reddish-brown sandy loam
which is usually less than 10 percent organic matter and slightly acidic
(pH 6-6.5) [33].

Pinelands occur on relatively elevated sites, which are usually only
shallowly inundated for less than 2 months (but may be inundated for up
to 5 months in wet years); these are shorter hydroperiods than adjacent
sawgrass prairies or cypress swamps.  Pine flatwoods with saw-palmetto
(Serenoa repens) understories usually occur on sites that are drier than
those occupied by subtropical pine forest [9].


VEGETATION : 
The subtropical pine forest as described by Kuchler [46] is a variant of
the south Florida slash pine (Pinus elliottii var. densa) type (SAF 111)
[11].  Other authors have described this community; it is variously
called rockland pine, pine rockland, Miami rockland pine forest, Miami
pine forest, and Miami Rock Ridge pine forest [6,7,8,10,43,55].  Like
the other south Florida slash pine types, it is composed of pure or
nearly pure south Florida slash pine in the overstory.  Its unique
feature is the understory of tropical (mostly West Indian) species of
hardwoods, shrubs, epiphytes, and palms [11].  Where information is
related generally to pine forests of southern Florida or has not been
specified as to community type by the authors, the term "pinelands" or,
where appropriate, "Miami Rock Ridge pine forests" will be used in
addition to "subtropical pine forest".

Robertson [30] suggested that subtropical pine forest is more closely
related to the "pine yards" on the northern islands of the Bahamas than
to other southern Florida pine forests.  Loope and others [23] recorded
a total of 186 taxa in 11 quadrats in subtropical pine forests within
and outside of Everglades National Park.  Of the 76 major species, 17
percent are endemic to southern Florida and an additional 7 percent are
endemic to Florida.  Nearly half (47%) of all the species have West
Indian distributions and 33 percent have temperate distributions
[4,24,33].  This flora contrasts with that of south Florida slash pine
flatwoods, which have understories of temperate species of shrubs
(mostly Gaylussacia spp., Lyonia spp., and Vaccinium spp.) and
saw-palmetto [11].

Virgin stands of subtropical pine forest were described by Harshberger
[15] as uneven-aged, open stands of trees up to 115 feet (35 m) tall,
with most trees under 200 years of age [9].  The Florida Natural Areas
Inventory recognizes three types of pine rockland, all dominated by
south Florida slash pine.  Keys Pine Rockland has an understory of
silver palm (Coccthrinax argentata), Key thatchpalm (Thrinax morrisii),
and tropical shrubs.  Dade Pine Rocklands have a shrubby tropical
understory characterized by many endemic species.  Big Cypress Pine
Rockland understories are dominated by temperate species [55].  In Big
Cypress Swamp, mature south Florida slash pine forests have a sparse
overstory which is usually no more than 10 to 20 percent canopy cover.
A subcanopy is rare; however, on fire-protected sites hardwoods can
reach tree size.  In subtropical pine forests of Miami Rock Ridge, false
tamarind (Lysiloma latisliquum) and live oak (Quercus virginiana) most
commonly reach tree size.  In pinelands of the lower Florida Keys there
is often a well developed subcanopy of silverpalm (Coccothrinax
argentata) and Key thatchpalm [33].

A number of species occur in the understories of all three subtropical
pine forest areas including willow bustic, coco plum (Chrysobalanus
icaco), strangler fig (Ficus aurea), shortleaf fig (Ficus citrifolia),
southern bayberry, myrsine (Myrsine guianensis), red bay (Persea
borbonia), indigo berry (Randia aculeata), southern sumac (Rhus
copallina var. leucantha), cabbage palm (Sabal palmetto) and
saw-palmetto [33].  Common understory species in the Miami Rock Ridge
area include silverpalm, coontie (Zamia floridana), running oak (Quercus
pumila) [1], rough velvetseed (Guettarda scabra), hammock velvetseed
(Guettarda elliptica), willow bustic (Dipholis salicifolia), hopbush
(Dodonea viscosa), longleaf blolly (Guapira discolor), poisonwood
(Metopium toxiferum), marlberry (Ardisia escallonioides), southern
sumac, and satinleaf (Chrysophyllum oliviforme) [6,46].  Species that
occur in the Miami Rock Ridge and the lower Keys but not in Pinecrest
include smooth strongbark (Bourreria cassinifolia), locustberry
(Brysonima lucida), silverpalm, pineland croton (Croton linearis), rough
velvetseed, buttonsage (Lantana involucrata), and longstalked stopper
(Psidium longipes).  Species that occur in Pinecrest and Miami Rock
Ridge but not the Keys include buckthorn (Bumelia reclinata),
beautyberry (Callicarpa americana), hopbush, dahoon (Ilex cassine), and
live oak.  Subtropical pine forests in the lower Keys have a number of
tropical shrubs that are not found in pine forests elsewhere [33].

The diversity of understory species in subtropical pine forest is
affected by adjacent communities.  Gumbo limbo (Bursera simaruba),
inkwood (Exothea paniculata), and false tamarind are normally found in
subtropical pine forest only near hardwood hammocks.  Subtropical pine
forests bordering on glades (sawgrass [Cladium jamaicense] marshes)
usually have a relatively depauperate shrub stratum, although some
species such as pineland wattle (Acacia pinetorum) and mullein
nightshade (Solanum donianum) are found mainly near pine-glade
interfaces [33].

The herbaceous understory is comprised of over 250 indigenous species,
nearly half of which are largely limited to subtropical pine forest
[33].  Dominant grasses include firegrass (Andropogon cabansii) and
Florida bluestem (Schizachyrium rhizomatum) [6,33,34].  Herbs restricted
to subtropical pine forest and commonly found in the Miami Rock Ridge
area include golden trumpet (Angadenia sagrae), smallleaf squarestem
(Melanthera parvifolia), pineland clustervine (Jacquemontia curtissii),
christmasberry (Crossopetalum ilicifolium), bastard copperleaf (Acalypha
chamaedrifolia), Florida sensitive-pea (Chamaecrista deeringinana), and
low rattlebox (Crotolaria pumila).  Ferns include ladderbrake (Pteris
vittata) and anemia (Anemia adiantifolia) [33].


WILDLIFE : 
Even though the flora of subtropical pine forest is largely derived from
that of the West Indies, native wildlife is composed largely of species
endemic to the southeastern Coastal Plain (and species with wider
ranges).  The West Indian elements of the fauna are mostly birds.
Virtually all of the common and conspicuous native vertebrates of
rocklands (including tropical hardwood hammocks) are widely distributed
on the Coastal Plain, including subtropical pine forests [33].
Dalyrmple [51] observed 30 species of herpetofauna on Long Pine Key (7
anurans, 2 turtles, 6 lizards, and 15 snakes).  Examples of vertebrates
occurring in the Miami Rock Ridge include southern toad (Bufo
terrestris), green treefrog (Hyla cinerea), black racer (Coluber
constrictor), red-bellied woodpecker (Melanerpes carolinus), Carolina
wren (Thryothorus ludovicianus), Virginia opossum (Didelphis
virginiana), hispid cotton rat (Sigmodon hispidus), raccoon (Procyon
lotor), and white-tailed deer (Odocoileus virginianus) [33].

Endemic vertebrates of rockland ecosystems are mainly relict populations
of North American species that were stranded in the Keys [33].  The rare
Miami black-headed snake (Tantilla oolitica) is restricted to sandy
soils over oolitic limestone and may occur in pinelands or tropical
hammocks [34].  A number of threatened subspecies of turtles, lizards,
and snakes occur in the Keys.  No endemic birds occur in southern
Florida rocklands, but a remnant population of red-cockaded woodpeckers
(Picoides borealis) persists in old-growth pine forests of Big Cypress
Swamp.  Birds that were once reported to breed in Miami Rock Ridge
forests but are no longer observed there include American kestrel (Falco
sparverius paulus), red-cockaded woodpecker, brown-headed nuthatch
(Sitta pusilla), eastern bluebird (Sialia sialis), and summer tanager
(Piranga rubra).  Endemic mammals in subtropical pine forest include
four species of rodents, three subspecies of raccoon, and the Key Deer
(O.  v. clavium), which is restricted to Big Pine Key and several
surrounding keys.  The Big Cypress fox squirrel (Sciurus niger
avicennia), Florida panther (Felis concolor coryi), and the Florida
black bear (Ursus americanus floridanus) all occur in rocklands but
range beyond them [33].


ECOLOGICAL RELATIONSHIPS : 
According to Egler [10], the Everglades and surrounding pinelands were
born in fire, survive only with fires, and are dying today because of
fires (i.e. severe fires occurring after years of fire exclusion or
suppression).  Subtropical pine forest is a seral community type that is
maintained by frequent, low-severity surface fire.  For further
discussion of the effects of fire on subtropical pine forest see FIRE
ECOLOGY AND MANAGEMENT.

Species composition of subtropical pine forest is also influenced by
hydroperiod.  South Florida slash pine will not grow in areas with
hydroperiods much longer than 2 months [33].

Second-growth south Florida slash pine stands on Long Pine Key supported
181 to 472 trees per acre (453-1,179/ha) with basal area up to 78 square
feet per acre (18.1 sq m/ha); second-growth stands in Turner River (Big
Cypress Swamp) averaged 36 trees per acre (90/ha) with basal area of 30
square feet per acre (7 sq m/ha) [34].

Subtropical pine forests contain plants with a wide variety of
phenologies.  South Florida slash pine is a true evergreen; its needles
live longer than 1 year and abscission occurs year-round but is minimal
from January to March.  Growth can occur year-round also, which causes
false annual rings and makes determining tree age difficult.  Some of
the temperate hardwoods present are obligately deciduous.  None of the
tropical hardwoods are strictly deciduous but many of them gradually
lose leaves during the dry season, flowering and producing new leaves in
the spring.  There are plants in flower or fruit all year long in
subtropical pine forest [33].

Important disturbance factors other than fire include hurricanes, which
usually have effect on a local scale, droughts, and freezes [6].

Related categories for Kuchler Type: Subtropical Pine Forest