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Wildlife, Animals, and Plants
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KUCHLER TYPE
KUCHLER TYPE: Southern mixed forest
KUCHLER-TYPE-NUMBER :
K112
PHYSIOGNOMY :
Tall forest of broadleaf deciduous and evergreen trees.
OCCURRENCE :
Southeastern United States, encompassing eight states: Florida, Georgia,
the Carolinas, Virginia, Alabama, Louisiana, and Mississippi. In
accordance with Ware and others [19], this report includes a slightly
larger area than that recognized by Kuchler [10].
COMPILED BY AND DATE :
S. A. Snyder, January 1994
LAST REVISED BY AND DATE :
NO-ENTRY
AUTHORSHIP AND CITATION :
Snyder, S. A. 1994. Southern mixed forest. In: Remainder of Citation
Kuchler Type Index
FEIS Home
KUCHLER TYPE DESCRIPTION
PHYSIOGRAPHY :
The Coastal Plain portion of this type is characterized by marine
terraces, on the seaward side of which are often found fossilized sand
dunes. Stream channels run throughout the southern mixed forest, and in
places subsidence has resulted in "drowned" river mouths. This type is
also characterized by bays, sounds, barrier islands, and wide estuaries.
Along the coasts in Florida and the Carolinas, the terraces are poorly
drained and may be saturated for part of the year. Inland terraces are
narrower and more dissected than coastal terraces. Relief may be
greater: 105 feet (35 m) compared to 45 feet (15 m) along the coast.
Differences in relief of only a few meters can affect vegetation in
these predominantly sandy soils [19].
CLIMATE :
The southeastern Coastal Plain receives more than 48 inches (1,220 mm)
per year of precipitation. This area has the highest frequency of heavy
downpours combined with the most rain-free days per year. It also has
the highest evaporation rates in the East [19]. For the whole area
average annual precipitation is between 40 and 60 inches (1,000-1,520
mm) and average annual evaporation is 42 to 48 inches (1,060-1,220 mm).
In the eastern part of this region precipitation is lowest in the fall
and highest in midsummer. In the west it is lowest in winter and spring
[7]. The southern mixed forest is subjected to annual hurricanes,
especially along peninsular Florida and the Gulf Coast.
The southern mixed forest experiences mild winters. Average monthly
temperatures from December through February are above 40 degrees
Fahrenheit (4 deg C), with inland areas slightly cooler than coastal
areas. Frost-free days occur from April first to November first, and
the growing season usually exceeds 210 days. Florida is the warmest
area in the southern mixed forest with milder winters, longer growing
seasons, and more frost-free days than elsewhere in the region [19].
SOILS :
Most of the soils in the Coastal Plains area are sandy [19], but range
from sandy or gravelly to moderately fine textured [7]. Soils in the
longleaf-slash pine type are typically acidic, low in organic matter,
and deficient in many essential plant nutrients [7]. In some places
older calcareous soils have been exposed by erosion. Phosphate-rich
calcareous soils are common in peninsular Florida and scattered
throughout the region [19].
VEGETATION :
The southern mixed forest region has been referred to as the oak-hickory
association or the beech-magnolia association based on potential natural
vegetation in the absence of fire [19]. Dominant overstory vegetation
is listed as American beech (Fagus grandifolia [not in central
Florida]), sweetgum (Liquidambar styraciflua), southern magnolia
(Magnolia grandiflora), slash pine (Pinus elliottii), loblolly pine (P.
taeda), white oak (Quercus alba), and laurel oak (Q. laurifolia) [10].
Loblolly pine now outnumbers the once abundant longleaf pine (Pinus
palustris) and slash pine. Maps of the presettlement range of
fire-maintained longleaf pine savannas have been reconstructed [19].
Presettlement forests of the Southeast, which were savanna woodland fire
types, survive only as scattered relicts. Now the vegetation is largely
postlogging, successional mixed pinehardwood forests [19]. Important
nondominant species include pignut hickory (Carya glabra), mockernut
hickory (C. tomentosa), redbay (Persea borbonia), and shortleaf pine
(Pinus echinata) in the northern range of this type; southern sugar
maple (Acer barbatum), American hornbeam (Carpinus caroliniana),
flowering dogwood (Cornus florida), inkberry (Ilex glabra), American
holly (I. opaca), yellow-poplar (Liriodendron tulipifera), wax myrtle
(Myrica cerifera), and eastern hophornbeam (Ostrya virginiana) in all
but central Florida; south Florida slash pine (Pinus elliottii var.
densa); cabbage palmetto (Sabal palmetto) in the eastern part of the
type; and southern red oak (Quercus falcata), bluejack oak (Q. incana),
turkey oak (Q. laevis), blackjack oak (Q. marilandica), post oak (Q.
stellata var. margaretta), live oak (Q. virginiana) and saw-palmetto
(Serenoa repens) in Florida and coastal areas [10]. Understory species
include wiregrass (Aristida stricta). Also found here are tickclover
(Desmodium spp.), lespedeza (Lespedeza spp.), butterfly pea (Clitoria
mariana), senna (Cassia spp.), tephrosia (Tephrosia virginiana),
galactia (Galactia spp.), wild indigo (Baptisia spp.), and Heterothea
graminifolia [19].
A publication listing vegetation types of the southern mixed forest
follows.
Vegetation of the Archbold Biological Station, Florida: an example of
the southern Lake Wales Ridge [1]
WILDLIFE :
The southern mixed forest is home to an array of animals that includes
opossum, raccoon, white-tailed deer, feral pigs, squirrels, warblers,
woodpeckers, the cardinal, flycatchers, quail, snakes, frogs, and
turtles [19]. For a list of endangered species see WILDLIFE VALUES.
ECOLOGICAL RELATIONSHIPS :
Before European settlement within the range of longleaf pine, mixed
forests dominated by American beech, southern magnolia, other hardwoods,
and semievergreen oaks may have been limited to small areas. Relict
old-growth stands are still found on slopes, swamp islands, and upland
flats on peninsulas. Due to a variety of moisture regimes and the
historic prevalence of periodic fires, the potential climax vegetation
following longleaf pine forests in the southern mixed forest is
difficult to predict. Various authors have tried to extrapolate this
information from trees present in second growth-forests [19]. See FIRE
EFFECTS ON VEGETATION.
Longleaf pine usually occurs in pure stands on dry sites and is
considered fire subclimax [6,20,21]. It is a pioneer on areas cleared
by stand-replacing fire and is maintained by fire on dry sites
[12,20,21]. Slash pine has shallow spreading roots and is found on more
wet sites that may seasonally flood. The two species may occur together
where fire has been absent for 5 to 10 years [21]. Loblolly pine occurs
on both well-drained and poorly drained sites and can establish
following fire [21].
Fire exclusion favors slash pine over longleaf pine in Florida and
favors loblolly pine over longleaf pine in the northern Coastal Plain.
On mesic sites where soils are rich in phosphate and calcium, American
beech and southern magnolia eventually replace pines in fire's absence
[8]. Sandy or nutrient-deficient soils usually do not support hardwoods
[3].
For more detailed information on community dynamics refer to Christensen
[5], Ware and others [19], and Eyre [21]. For more detailed information
on community dynamics related to fire in the southern mixed forest refer
to Ware and others [19].
KUCHLER TYPE VALUE AND USE
KUCHLER TYPE: Southern mixed forest
FORESTRY VALUES :
Intense logging from the late nineteenth century until the 1930's
virtually eliminated all virgin stands of the southern mixed forest.
There are about 15,315,000 acres (6,202,000 ha) of loblolly and slash
pine plantations in the southern mixed forest, all of which are grown
for pulpwood and sawtimber [19].
RANGE VALUES :
Clearing of the southern mixed forest for grazing and agriculture began
more than 400 years ago [19]. Agriculture is now a dominant use in the
region.
WILDLIFE VALUES :
The southern mixed forest provides habitat for many threatened and
endangered species including the red-cockaded woodpecker, Bachman's wood
sparrow, the gopher tortoise, the Florida gopher frog, the indigo snake,
the pine snake, the pine barrens tree frog, the Florida mouse, and the
southeastern fox squirrel [19].
OTHER VALUES :
From Colonial times through the early twentieth century longleaf pine
was used extensively for tar, pitch, rosin, and turpentine. This
decimated longleaf pine stands throughout the region by the 1920's [19].
MANAGEMENT CONCERNS :
Ninety-seven percent of the uplands in the southern mixed forest consist
of converted lands and vegetation that is present due to disturbance.
Now less than 3 percent of the original landscape is natural vegetation.
Feral pigs can consume up to 400 longleaf pine seedlings apiece per day
[19].
KUCHLER TYPE FIRE ECOLOGY AND MANAGEMENT
KUCHLER TYPE: Southern mixed forest
FUELS, FLAMMABILITY, AND FIRE OCCURRENCE :
The southeastern United States has one of the highest-known incidences
of thunderstorms in North America, and lightning-caused fires are very
common [8]. Some traits of southern pines related to fuel loading and
fire resistance have been listed [11].
Along the coast from Virgina to Texas, there are thousands of square
miles of land without a natural firebreak. Firebreaks occur more
inland, where historic fire frequencies were probably lower than in
coastal regions. During early European settlement, accounts describe
Native Americans using fire during fall and winter to drive game
animals. This could be done once a year in most areas because enough
fuels accumulated in one year to carry fire. Along the Coastal Plains,
fuels did not accumulate due to annual summer lightning fires, and
effects of burning by early Native Americans were probably negligible
[19].
Studies in longleaf pine savannas show that fires are usually low
intensity surface fires and rarely reach the crown. Longleaf pine
needles are highly flammable, and areas with more and larger trees
usually burn hot if litter has accumulated [15]. More than 100 years
ago, the fire maintained longleaf pine savannas had an average fire
frequency of 1 to 3 years. In areas of slightly lower fire frequency
(5-10 years) mixed pine savannas and woodlands dominated [19].
FIRE EFFECTS ON SITE :
Burned soils in longleaf pine forests show higher average temperatures
than soils in unburned areas. Soil moisture is as much as 50 percent
lower on burned sites; with repeated burning, water-absorbing ability of
longleaf soils decreases from 50 to 80 percent. Some studies report
that organic matter and nitrogen may also be lost with frequent fire on
abandoned old fields. Other reports show that organic matter and
nitrogen may increase after fire in virgin forests. This could be due
to an increase in leguminous species and charcoal deposition following
fire. These differences may be accounted for by comparing differences
in species composition and biomass between oldfield and virgin forest
communities [6]. Detailed effects of fires on soil nutrients in Coastal
Plain forests and their subsequent effects on vegetation have been
listed for Coastal Plain forests [4].
FIRE EFFECTS ON VEGETATION :
Fire played a major role in determining presettlement vegetation. Its
effects on vegetation depend on soil moisture and topography. Longleaf
pine is the only tree in this region whose seedlings are adapted to
survive fire [19]. Most longleaf pine growth during the first 5 years
is concentrated in the roots, which enables it to survive even when the
leaves are consumed by fire [20]. Even then few seedlings may escape
fire [22], but in virgin old-growth stands, one surviving seedling every
5 to 10 years could be enough to maintain a fully stocked stand [19].
Hot fires due to heavy needle litter accumulation can kill longleaf
seedlings [21]. Longleaf pine perpetuates in pure stands when burned
during winter every 3 to 4 years. Associated pines (loblolly,
shortleaf, and slash) are more adapted to fire cycles of 10 to 15 years
[6].
Slash pine is highly susceptible to fire during its first 2 years and
vulnerable throughout the seedling stage [12,20,21]. After 10 to 12
years it can survive winter fires that do not crown. If less than 40
percent of its crown is scorched, slash pine growth may be enhanced by
fire. The south Florida variety is more resistant than the typical
variety [20].
Loblolly pine is not fire tolerant during its first 10 years, but mature
trees are relatively resistant [2,20]. Mature trees with thick bark can
survive low- to medium-severity fires [18]. After loblolly pines have
reached 2 to 4 inches (5-10 cm) in diameter, they can be burned in
winter every 5 to 10 years, which tends to suppress hardwoods [20].
Fire has the following effects on additional canopy dominant species (as
listed by Kuchler): American beech is fire-intolerant. It can sprout
following fire, but is susceptible to decay [3,16]. Sweetgum too is
damaged by fire, opening it up to decay. It is more susceptible to
summer fires than winter fires, but it does sprout following fire [9].
Southern magnolia is usually top-killed by fire, but can sprout [14].
Because of its thin bark, laurel oak is usually top-killed by light
ground fires, but can sprout [13]. White oak needs periodic fire to
perpetuate because it is shade intolerant. It is moderately resistant
to fire and can sprout [17].
Important understory species in longleaf pine and slash pine stands,
saw-palmetto and inkberry, are highly flammable. If not burned during
winter every 3 years, fuel loading of these species can lead to fires
severe enough to kill both the understory and overstory [12].
For more detailed information on fire's effects, refer to species
write-ups in the FEIS database.
Some vegetational patterns related to fire frequency in presettlement
southern mixed forests were as follows: On dry, upland sites frequent
fires maintained longleaf pine savannas. Turkey oak was also present in
these stands. Fire may have been less frequent on dry sandhill sites
because of dissected topography and sparse fuels. As moisture
increased, longleaf pine occurred with slash pine, bluejack oak,
blackjack oak, and post oak. Shortleaf and loblolly pines may have also
been present. Pond pine occurred on moist sites where oaks were absent.
Where fires were less frequent, longleaf pine and red oak dominated on
dry sites. On moist sites longleaf pine was less prevalent; slash,
loblolly, and shorleaf pines were more likely to occur with oaks.
Beech-dominated stands probably occurred where areas were isolated from
fire [19].
FIRE EFFECTS ON RESOURCE MANAGEMENT :
The mesic, species-rich longleaf pine types, which need fire every 1 to
3 years, are in danger of extirpation [19]. With the exclusion of fire
in recent decades, longleaf pine stands have been replaced with slash
and loblolly pines. If not for intensive timber production and
prescribed burning in the Southeast, all pine species would be a small
part of the climax forest. Prescribed burns are an effective way of
maintaining pine forests and of reducing severe wildfire hazards in this
region [20].
Fire promotes palatable grasses and forbs under longleaf pine forests
for livestock grazing and wildlife [12].
FIRE USE CONSIDERATIONS :
Fire can be used to control brown spot disease, to which longleaf pine is
very susceptible [20].
FIRE MANAGEMENT CONSIDERATIONS :
On outer terraces of Coastal Plains, slopes greater than 15 degrees
serve as effective fire breaks in longleaf pine savannas. Fires in
these areas usually originate on the upland flats and not in the
bottomlands [19].
REHABILITATION OF SITES FOLLOWING WILDFIRE :
NO-ENTRY
REFERENCES
KUCHLER TYPE: Southern mixed forest
REFERENCES :
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2nd ed. New York: McGraw-Hill. 686 p. [15993]
3. Christensen, Norman L. 1981. Fire regimes in southeastern ecosystems.
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technical coordinators. Fire regimes and ecosystem properties:
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their effects on the vegetation of the Coastal Plain of the southeastern
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fire effects workshop; 1978 April 10-14; Denver, CO. Gen. Tech. Rep.
WO-16. Washington, DC: U.S. Department of Agriculture, Forest Service.
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13. Curtis, James D. 1946. Preliminary observations on northern white cedar
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of fire in the Appalachians. Gen. Tech. Rep. SE-54. Asheville, NC: U.S.
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18. Wahlenberg, W. G. 1960. Loblolly pine, its use, ecology, regeneration,
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hardwood forest: the former longleaf pine forest. In: Martin, William
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southeastern United States: Lowland terrestrial communities. New York:
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Index
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