THE Im1?Ar 3?F Ar SEASON AND D2Y SEASON ?BEPSt-"RFn PT'
ON irAMI ROCK PTDGE PTNELAND, SOUTH LOIT'A
JAMFS R. SIUYDiF
A DISSPRTArION PNESESTFD TO THE S3ADUATF SCHOOL
OF THE UIV?.RSTTY OF FLORIDA TN
?4?TIAL PULPILLNEN'T OF T? ?OnfTREMPFmTS
P?)3 rE DEGREE OF DOCTOR OP P!ILOSOP'Y
UNIVI7SITY 3?F LORIDA
Tha major portion of this work was supported directly by
the South Florida Research Center, Everglades %ltional Park,
and I owe s3ezial thanks to Dalq Taylor, formerly fire
ecologist, ai Gary Hendrix, research director. Numerous
individuals it th= Pesearch Center aided in the filll wor:;
in particular Rebecca Rutlelge, Virginia Louv, Arthony
Canrio, Laeis Sharman, ani Donna Blake spont many hours
under trying conditions. Alan Heraion, besides helning with
fill work, identified plants and shared his knowledae of
local plant :ommanities. Pill Robertson, Jr., hloe1 snrac
my interest in tasse unusual pinlands. The ?or? r=snur7?
manaqgemnt staff (lead by fire bosses Phil Foeon, Leon '~nz,
ini Ron Sutton) 3arriel out the prescribed burns. ?aul rrt!
of the AgrLcultural Research and Education Center,
Homestead, generously permitted the use of his facilities
for tissue grinding.
In gainesville my committee chairman, Jack Ewel, provided
logistical sioport, advice, and guidance. Committee nembbrs
Seorge Bowes, Walter Judd, and Tugh Popenoe made useful
comments and suggestions throughout the study. Jack Pu'z
provided a tiorogh review of the manuscriot and sqsested
numerous impcovenents. Mary McLeod, Craig Peed, and Linda
Lee of the Forest Soils Lab were of great technical
assistance with the chemical analyses. George u1ller
drafted most of the figures. Xen Portier aevised on
statistical nattscs. computing was done with the facilities
of the Northeast Regional Data Center.
In recognition of less tangible contributions, I thank n7
father, Robert Sayder, for instilling in ae an aopre-iation
of the great out-of-doors and my wife, Jean Snyder, for
continuing encoucagement and support.
TABLF OF CONTENTS
ACK O L G TS . . . . . . . . . ii
ABSTS ACT . .. . . . . . vi
I. NTRODU TCrT . . . . . 1
Dbjpctivos . . . . . . . .. . .
he ecosystem . . . . . . 3
Cli e . . . . . . . . 3
a-ol3gy and Soils . . . . . . . 7
Vegetation . . . . . . . 11
'ire Ecology . . . . 17
?rPasnt Extent an- Conlition . . . .
7verVlades National ark . . . . 2
II. 'T.O S . . . . . . . . . . 27
7xporimnatal Design and Site Selection . 27
The Burns . . . . . 29
Abajeqrannd Mass Sampling .. . . . . 31
eagetatian and Litter . . . , . 31
?3stburn Ash . . . . . . . . 34
Litterfall . . . . .. . . . 35
Soil Sampling . . . . . . . .. 36
issue and Soil Analysis . . . ... . 37
ITT. RESULTS . . . . . . . . . . . 39
Tnitial ageattion Structure . . . . .. 39
Burn Descriptions . . . ... . .. . 4
Pica Effects an Unlerstory Mass aan Nutrients .r2
faitial Distribution of Mass an! Nutrients 52
ksh Collection methods . . . . .
?ost3urn Distribution of Mass ard Nutrients 57
Postfica Recovery of Mass and Nutrients . 58
vegetation .9.. .. ... .... . B
Littr. ...... .......... .. .70
Impact of Fires on Pines . . ..... .. 75
Soi . . . . . . . . . . .. . 79
IV. DTSC SS N . . . . . . . . . 32
Fice-caused Losses of Nutrients . . ... 2
?3stfice Recoverv . . . . . . 0
TfE~at 3f Season aE Burning on Hardwool recovery 93
Regrovti Vegetation as a Nutrient Sin .- . 101
Sumnary and Conclusions . .. . . 10
LITE RAT ED . . . . . . . . . 11
A. VASCULIS PLANT TAXA PRESENT IN STUDY PLCTS . 124
B, STANDI13 ;ROPS OF DRO MASS AND NUTrTTS . . 130
1ETB PAPHICAL SETCrH . . . . . . . . .
Abstract of Dissertation Presonte~ to the (raduite School
of the Universitv of 7lorida in Partial F lfillmeon' f the
Requir3en2ts for the Degree of Doctor of Philosophy
THP IIPACr DF WET SASSDN AND DRY SEASON ?PFSCrT'D) "TiP
3N rEA1I aOCK RIDGE PINELAND, SOUTH PLOISDA
James R. Snvyer
Chairman: Join J. Ewel
Major Department: Botany
In the subtropical pine forests on oclitic li.mstone in
Dade Countv, "lorida, "inu3 elliottii var. 3easa qrows over
a species-cizh unaarstory (> 128 sop.) 3f shrabbh hardwoods
(mostly tropi-cl evergreen species palms, and herbs,
including several endemic taxa. Fires prevent rapid
conversion to hardwood forest. To compare the response of
these pinelais to burning during the lightning Cire season
(hot, wet, summer months) and the management fire season
(cooler, drier, winter months), aired burns were condnc't?
at two sites in Rverglades national Park, one bi=rnd 3., vr
previously and the other 5 yr. Aboveground inderstory
biomass and attriants were measured immediately before and
after, and it 2, 7, and 12 mo after the four burns.
The burns topkilled all the understory vegetation. Thp
fires volatiLizel 1-1.5 kg/m2 of organic matter and 5.7-".
g/m2 of N. Meteorological inputs and symbiotic and
nonsymbioti Efixation should easily replace N lost in the
burns. Losses of P, K, :a, and Ig were not letectable
except for K in one of the burns.
The rapil un]irstcry recovery was almost entirely
vegetative rgrowth of the topkille9 plants. 'ine seenlin4
were abundant after the wet season burns, however. fera;
and palms recovered dry mass more rapidly than hardwoods an,
reached prebucn levels within 1 yr. Hardwoods recovered
only, 18-39% of their preburn biomass. Total understory
vegetation re3ovecy was 27-63: of initial amounts, but
leaves rpecovceI 58-931. Net primary prodlctivitv t'- first
year after burning was 144-200 g/m2.
Recovery if nutrients was more rapid than bioass because
of higher nutrient consentcations in regrowth tissues. Some
herb and pall nutrient standing crops reached preburn levels
within 2 mo.
After the burns litter mass and nutrients often showed an
initial decrse before recovery began, kt 1 vr litter iass
was 42-62" of the prebnrn amount. Annual pinon no1=lef-ll
averaged 260 and 320 g/m2 at the two sites,
The iaouat ff hacrwood recaverv was not determined by
season of burning; higher fire temperatures (wet season b'rn
in one case, 3ry season burn in the other) resulted in less
The importance of fire as an environmental factor
influencing ecosystem structure and function is widelv
appreciated today (Ahlgren and Ahlgran 1960, KozlowsIi and
Ahlgran 1974, Moanev et al. 1981, Rundel 1981, Wright ana
Bailey 1982). Fire is often thought of as a succ-ssion-
initiating listurbance (White 1979). However, in
communities that iave evolved under a regime of frequert
fires, it is tie exclusion of fire that may result in
3raiatic--if not su3ian--changes. Much of sonth?-stern
U.S., particularly the coastal plain, is covere wvith
vagatation that requires periodic burning (Chris~'nsn
1981). lany southern pine forests, for example, levelon
into hardwool forests in the absence of burning warren n
The regrowth vegetation in some frequently burned '
ecosystems comes Erom seeds present in the soil or release!
from killed plants. gore commonly, however, individuals
survive and sprout back from belowgrouni parts. In
chaparral it is common for species to show mixed s'-1ling
and sproutinJ recovery mechanisms (Keeley and Koeley 1991).
Fire is very prominent in South Florida ecosystems, both
in terms of area burned and as a leterminant of vegetation
pattern (,obertson 1953, Wa3e et al. 1980). Of particular
interest in this study are the subtropical pinelands founi
on the Milni Rock Riige in southeastern vlorida. These Dine
forests differ Erom other southeastern coastal plain oina
forests in two ways: they include a large number of
tropical species in the understory and they grow directly on
a limestone substrate nearly devoil of soil.
Prescrib.l fire is used throughout the southern nine
region for site preparation, fuel reduction, and range
improvement. It has also become a tool in natural area
management in places such as Everglades National ?ark. Tn
most southeastern pine forest types (with one maior
exception) fire loes not kill the canopy trees as it locs in
many conifernos forests (Heinselman 1973). This, along wilt
its common use for other purposes, may be why the us0 of
intentionally set fires was so readily accepted as
management techniLue in natural areas.
Prescribed burns in the southeast are traditionally
carried out lurina the cooler months because fires durirg
this time are less likely to damage overstory trees and
because the casprouting vegetation provides forage vhich is
otherwise limited at this time. Before the influence of
humans, however, fires were primarily ignited bv lightning,
which occurs during warmer months.
i wished to examine some ecosystem-level responses on
Miami Rock Ridge pinelands to fires during the natural
lightning-cuaisd fire season and the traditional nanagament
fire season. T was particularly interested in the
(1) The amount of mineralization and loss of organic
matter and natrients due to fires.
(2) The pattern of recovery of understory mass and
nutrients during the first year after burning.
(3) The degcre of recovery of the unnarstorv 1 yr af'er
burning, viti :mplasis on the recovery of hardwoods.
(4) Rasad on the above items, to draw some conclusions
about the potential role of fire in nutrient cycling and the
use of pres=ribeS fire in the management of a natural area.
The cliiate of South Florida has two salient features:
(1) moderate, almost frost-free winter t=aperatures and f2)
a marked seasonality in rainfall (?ig. 1). These
characteristics result in a hot period of high rainfall
(May-Oct.) and a cooler period of much lower precipitation
(Nov.-April These are known as the wet and Irv seasons,
respectively, in keeping with tropical terminology.
.555 F;~ :. .... ..... ,.. .
J F M A M J J A S O N D
Figure 1. Mean monthly precipitation (bars) and
temperature (dots) at Royal Palm Ranger Station,
Everglades National Park (after Rose et al. 1981). Mean
annual rainfall is 146.3 cm.
Mean montily temperatures range from about 18.0oC in
December an3 January to about 27.50C in July and August.
Prosts occur in the homestead area about once every two
years on the average (Brallev 1975). These frosts can
damage winter vegetable crops and production of avocados and
mangos for the ensuing year. Many of th3 native plant
species are also susceptible to Erost damage (Craigheal
1971), soaecially plants in open areas. freezingg
temperatures were recorded during both 1981 and 1982, bit
the study areas were little affected. Only a few of t'h
minor species dropped leaves and none hal stems kili"d.
Total annual rainfall averages 146 cm in the southern
portion of tia Miami Rock Ridge, with almost 90: (117 ca)
coming during the six wet season months (Fig. 1). 7ater
levels vary seasonally with a maximum in Senotaber and a
minimum in Aoril, During the wet season clous" bnil, un iL
the afternoon and result in brief thundershowers; the
lightning that accompanies these storms is a potential
ignition source for wildfires. Although most summer
rainfall is :onve:tional, tropical cyclones can bring large
amounts of rain. In August 1981 Long Pine Key in Everglades
National Pinr received more than 40 cm of rain in thrs dItys
from tropical storm Dennis.
The soutaeastern coastal area of 'lorida can exact a
tropical cyclone once every 5 yr and a hurricane-fnrce storm
once everv 7-9 yr (Gentry 1974). The damage to vegetation
in South Fladria by hurricane Donna in 1960 was substantial,
especially in th~ mangroves on the southwest coast
(Craighead and gilbert 1962). The pinelands of Wveralades
National Park suffrsed little damage in spite of
experiencing wind speeds greater than 160 km/hr. Th? hiah
water levels Orought on by heavy precipitation can affect
the pineland vegetation more strongly than the high vinds.
although South Florida is north of the Tropic of Cancer
(Long Pine Key is about 250 23' N latitude it is commonly
referred to as "tropical Florida," especially hv those
concerned with fl3ristics (e.g., Tomlinson 19i0, Lona and
Lakela 1971). In fact, a world-wiie climatic classification
scheme based on that of Koeppen (Ccitchfield 197u) considers
the southern tip of Florida to have an Aw, or tropical
savanna, linate of the vet-and-dry tropics. It is included
as a tropical climate only because the mean monthly
temperature of the coolest month is greater than 180C. T"-
common occurrence of frost at sea level would perhaps ma~k
subtropical a better designation for the climate. The
classification system of Holdridge (1947), which is based on
temperature ian precipitation, places southern Florida in
the Subtropical Ioist Forest life zone.
Geolo yand Soils
South Florida is extremely flat: a function of its
marine depositional history, low elevation, and relativelv
short periol of emergence. The broad, shallow Pverqlades
basin which ertenis south from Lake Okeechobee is bounded on
the east by the slightly higher Atlantic coastal ridge. Thp
southern end of this ridge in Dade County is an outcropping
of oolitic limestone known as the !iami Rock Ridge (Davis
1943). This region, previously dominated by pine forests,
extends from the vicinity of ?iami southwestward to
Homestead ani westward into Everilades National Park (Vin.
2). The mai[mum elevation of the ridge is about 7 m in
Coconut Grove (Hoffmeister et al. 1967) and it drops to less
than 2 m in everglades National Park, where it disappears
under the surrounding wetlands,
The iiami Limestone (rqoffmaister at al. 1967) which m'ake
up the Miami Rock ?idje is the surface rock of virtulallv all
of Dade County. It represents Pleistocene marine deposition
of calcium carbonate during the Sangamon stage (Cooke 19ac).
The upper oolitic faces which forms the rock ridge is
composed of Doids, pellets, and some skeletal sand. To th=
north along the coastal ridge the limestone is blanketed by
a layer of Pamlico sand, and at lower elevations to the west
and south it may be covered with late Pleistocene or "eccen
marls and pets. Several transverse depressions nassina
through the ridge represent valleys in tha rock that have
been partially filled by deposition of marl and/or organic
matter (igs,. 2 and 4).
The formation of the Miami Rock Bidge is described hv
Hoffmaister :t al., (1967). They compare it to processes
occurring tolay on the northwest section of the greatt Bahama
Bank, where loose mounds of ooids are forming and shifting
in the shallow water on the eastern edge of the Straits of
Florida. The tilal channels that cut through the broal
ridge of unconsolidated oolitic sediment are thought to be
analogous to thos that form the transverse valleys in 1h,
Miami Sock Ridge.
The oolite rock is soft and friable until indurated hv
exposure to the atmosphere. Dissolution of the rock has
left the surface honevcoibed with numerous holes and
fissures, anl armed with sharp, jagged projections. In i's
most treachercus form it is known as pinnacle rock. Th'
diameter of solution holes can range from centimeters to
meters as can the depth, although 0.5 m diameter and 1 m
depth might be common dimensions for the larger holes. The
character of the rock surface varies from place to olace,
with differences in the degree of solution and the amount of
loose rock fragments on the surface.
In the pineland areas of the Miami Rock Pilqe the scanty
soil is founi in solution holes, depressions, and cracks in
the rock. The soils are members of the Rockdale series,
which is classified as a Lithic Ruptic-Alfic -utrochrcpt,
clayey, mizel, hyperthermic (Soil Survey Staff 1975), 'he
surface soils range from dark grayish brown to brown fine
sands or fin* sandy loams. The subsurface layers (where
present) are light gray to yollowish-red fine sand and brown
to reddish-bcown sandy or clay loams (Soil Conservation
Service 1958). In the northern portions of the ridge in the
Miaai area, the soils tend to be very sandy due to
deposition oF sands during the Pamlico stage. To the south
there are often reddish-brown residual soils; the
predominance of these soils in the area !ist north of
Homestead is responsible for the appellation "3llands" qivan
to the area. In most areas there is little soil ezposed on
the surface ind plant roots run through cracks and channels
in the rock that are filled with a mixture of organic matter
and weathering products of the limestone. causee the roc'
ridge is the highest part of 'he landscape and is formc of
porous limestone the soils are generally well-drained,
However, high water tables can reach the ground surface in
the lower lying areas during the wet season. The soils are
neutral or slightly alkaline in reaction and are deficient
in N, P, and K for agricultural crops. The fact that the
exploitable soil volume is so small also contributes -n
making this i very oligotrophic ecosystem.
The nearly frost-free dry season makes southern vllrila
in important production area for winter vegetables. Current
farming practices require extensive site preparation before
production. After bulldozing off the native vegetation the
surface 15 cm of rock is scarified with heavy eguinment
(rock plowes), resulting in a "soil" composed of a mixtur-
of rock fragnants, pulverized limestone, and a saill iaount
of original soil. This treatment increases the rooting
volume and raises the pa t3 8 or higher. Crops (such as
tomatoes, squash, and pole beans) req'iire heavy
fertilization and irrigation. Experience in Everglades
National Parr suggests that once the substrate has bee-
altered in tais way the native vegetation does not normally
The vngetition of the Miami Rock Ridge is essantiallv a
mosaic of three basic vegetation types: pineland, hamoc',
ani prairie. Te pinelands form the dominant matrix on -he
higher grounI, with small islands of tropical hardwood
forest known as hammocks scattered within this matrix. Tn
the shallow transverse depressions that run through the
ridge are herbaceous prairies, or glades, similar to the
vegetation bordering the ridge. Long (1974) estimates that
the vegetation of South Florida is about 5,000 yr old.
2nsnral dessciptions of the natural vegetation of southern
Florida, including the rock ridge, have been provided by
several authors: Harshberger (1914), Harper (1927), Davis
(1943), Craijhead (1971), and Rade et al. (1990).
hammocks ice patches of closed forest of essentially
evergreen, bcoadleafed trees. They are found in the higher
areas of the ridge; where they are seldom flooded, if ever.
The soil is a thick layer of organic matter that has
accumulated on the surface of the limestone. Tmoortant
canopy species include Nectandra coriacea, Coccoloba
diversifolia, 212E c S IEiriniana, Lysiloma latisi5ionm,
12Metpiu toiferau, Ficus aurea, gBumlia salicifolia, and
Bursera simacuba (Phillips 1940, Alexander 1967, Craighea!
1974, Olmste3 et al. 1980a). Of these only Q, virinia.ns is
not a typically tropical species. The unierstory consists
of saplings of the canopy species, a number of small tree
species, and a a few shrubs. Relatively few herbs are
present on the ground, but epiphytic bromeliads an! -rchis
are quite common.
The seasonally flooded prairies that border the lovwr
fringes of tie pinaland are Dominated bv grasses and sedes
(e.g. juhlenberjia filip2s and Clalium jnamaicens:) but
include numaeous forbs (Pocter 1967, Olmsted et al. 1983).
Here the water table is above the ground surface for 2-'1
3m/yr and the limestone is topped with a thin layer of marl
(Olasted at al. 1980b).
The pinelinds, which oc-upy most of the iami pock Ridge,
are monospecLfic stands of Pinus elliottii var. tn4a, the
South Plorida slash pine, with a diverse understory of
palms, hardwoods, and herbs. The South Florida varietv o.
slash pine differs from the commercially important northern
variety (var. alliottii) in several respects (Little and
Dorman 1954a,b). lost conspicuous is the grass-like
seedling stige reminiscent of Pinus palustris (lonqleaf
pine) in which the seedling grows for several years without
stem slongatLon. wavever, Squillace (1965) showed more or
less continuous variation across the range of slash pine for
12 traits, i2cluiing seedling height and stem diameter. "'ho
range of Souti Florida slash pine extends from the Lower
Florida Keys to about Polk County in the center of
peninsular Florila and Levy and Volusia Counties alonq the
Gulf and Atlantic coasts, respectively (Langdon 19A3).
Sandy flatwools are a more widespread habitat for South
Florida slash pine than the limestone of the "iami lock
In contrast to the monotony of the pine overstory, +h-
understory is relatively species-rich. The shrub layer is
composed of 15-25 hardwood species per 0.16 ha (Loope et al,
1979), most of which are tree species maintained as shrubs
by repeated fires; the palas Sabal palmetto, Serenoa reens,
and Coccothrinax ar entata; and a cycad, Zamia numila.
Hardwoods commonly found as shrubs in the pinelands and as
trees in himmocks include letonium toxifarum, Sum-lia
salicifolia, srXEsine flori3ana, Guettarla scabra, anC
Ardisia escallonioides. Most hammock tree snpcies are founI
at least occasionally growing in pineland. Some smaller
shrubs (e.g. Dolonaea viscosa, Lantana de rEEssa, and t.
involucrata) are found in the open oinelanas but not in the
shade of hammocks.
Most of the hardwoods are West Indian in distribution and
are found only in extreme southern Florida or along the
coast to northern Florida. Only a few of the more important
species are founl as far north as Gainesville, 'lorida:
Rhus conalli a, zrEica cerifera, llex cass.in, Persea
borbonia, ini Q!erzus virriniana. Notably absent from th-
rock rid3j pinalinds are llsx lab hp (gallberrv) and members
of the Ericaceae, s3 important in most southeastern
pinelands. Apparently the high soil OH excludes these
species. Tie biogeography of pineland shrubs in South
Florida, including the Miami Rock Ridge, has been detailed
by Robertson in Olmsted et al. (1993).
The herb Layec is dominated by grasses but also contains
seiges, forbs, and three common ferns. The number of herh
species per 0.16 ha varies from 50 to 75 (Loope et al.
1979), The relative importance of hardwoods, palms, an1
herbs varies depending on local elevation and fire history.
In the lower, vwtter pinelands the understory tends to have
fewer hardwoods and has an herb layer that shares many
species with the prairies. ?reaaently burned sits have
better developed herbaceous layers than infrequently burned
Loope et il. (1979) list 196 plant taxa for the rock
ridge pinelaais, an3 67 of these are restrict!I to pineland
habitats. Tha number of South Florida endemics found in
pinalands (32, 17 of which are found exclusively in
pineland) is by far the highest for any South Florida
vegetation type (Avery and Loope 1980a). All the endemics
are herbs ex~:pt for the shrubs ForestiEra speqceata var.
2inatorum an Laitana L dl erssa (Table 1). South 'lorida
slash pine, although found north of Lake Ckeechobee, is
endemic to peninsular Florida and the Florida Keys.
The pinalians most similar to those of the Miami Pock
Pidge ire those of Pig Pine Key and several other Lover Fnvs
where the Miami Limestone also outcrops. These pinelands
differ mainly in the presence of several tropical hardwoods
characteristic of the Florida Keys or nearby coastal areas
and the oroninence of tree-size~ palms of Coccothrinav
arqgntata and Thrinax morrisii (Alexander and Dickson 1972).
The pinelanis of the Bahama and Caicos Islands are also vsry
similar to those of the rock ridge except that tha pine is
P. caribaea var. bahamensis (March 19U9, Luckhoff 1964,
Lamb 1973). The substrata is weathered coralline limestone
very much lit the oolitic rock of South Florida. many of
the understocy species are the same as those found in rock
ridge pinelinas (Coker 1935, Correll and Correll 198?),
although Robertson (1962) noted the conspicuous absence o"
Sersnoa renens. Even though it grows in an ecological
Table 1. Vascular plant taxa endemic to South Florida and
found in Miami Rock Ridge (MRR) pinelands,
including those of Everglades National Park
(after Avery and Loope 1980a).
Exclusively Present in
Taxon in MRR Everglades
Pinelands National Park
Amorpha crenulata *
Argythamnia blodgettii *
Aster concolor var. simulatus *
Brickellia mosieri *
Chamaesyce conferta *
C. deltoidea var. adhaerens *
C. deltoidea var. deltoidea *
C. garberi *
C. pinetorum *
C. porteriana var. porteriana *
C. glandulosa var. simpsonii *
var. angusta *
Evolvulus sericeus var. averyi *
Forestiera segregata *
Galactia pinetorum *
G. prostrata *
Hyptis alata var. stenophylla *
Jacquemontl curtisii *
Lantana depressa *
L. carter var. carter
L. carter var. smallii
Melanthera parvifolia *
Poinsettia pinetorum *
Polygala smallii *
Schizachyrium rhizomatum *
Stillingia sylvatica ssp. tenuis *
Tephrosia angustissima *
Tragia saxicola *
Tripsicum floridanum *
setting virtually identical to that of the roci ridge, .
caribaea vic. bahamensis do0s not have the grass-like
seedling stage that characterizes South ilorida slash pine.
It should be noted that for many years P. gll.l-tiii o
southeastern U.S. was considered the same species as P.
caribaea of the West Tndies and Central America P(Little ard
The rock cidge pineland, like most southern pine forests
(!arran 1943), is a fire-maintained vegetation type that
develops into hardwood forest in the absence of turning.
Robertson (1953) estimated that within 15-25 vr of the
cessation of burning, open pine forest would become sensee
hardwood focSst (hanaock) under a stand of relic pines; this
happened in a small area of pine forest in 7ver la=s
National Pack that was protected from fires by the
construction of a road (see photographs in Wade et al. 10)0,
p,93), Alaian~ic (1967) documented the rapid succ-ssion o'
pineland to hammock elsewhere in the rock ridge. The
succession to closed hardwood forest results in the
elimination of sose shrub species and the rich herbaceous
flora characteristic of pinelands (Loope and Dunevitz 1991).7
This is probably due to the reduction in light ceachinq the
ground but it may also ba due in part to the thick
accumulation of organi' matter that is normally removed by
fires. Loops and Danevitz (1981) found fewer species in a
frequently barnel piaeland than in a pineland unburned For
Fires in pinelands are surface fires that move along the
ground consuming litter and understory vegetation. Thp
density of the pine canopy is such that crown fires are
unknown, although the trees can be killed by convectional
heat under severe burning conditions. Prairies burn readily
when sufficient fuels are present but hammocks under normal
circumstan-cs do not. Pineland fires usually burn lin to th"
edge of hammaiks ani go out; however, during extreme
droughts the fire nay smolder through the hammock, consuiin'
the organic soil and killing the trees, Craighead (197U)
suggests that once soil moisture content in hammocks drons
to 351 they ire susceptible to soil fires.
All the species present in thq oinelanis are adapted '
fires. ~lture slash pines are very resistant to fire
because of a thick, insulating bark and the relatively heavy
buds surrounaed by long needles (Hare 1965b, Bvram 19U8).
Both varieties of slash pine are able to recover from 100'
crown scorz= in some cases (Wade 1983, personal
observation). Besides being fire-resistant as an adult, the
South Florida slash pine has a fire-resistant seedling stag
much like lonaleaf pine (Littl- and Dorman lq54a,b). An
accidental fire in a plantation of both var. densa and var,
elliottii seeilings killed a smaller proportion of th? South
Florida variety (Ketcham and Bethune 1963). Seedling
establishmint is also favored by fires occurring soon before
seed fall (Klukas 1973).
The hardwoods in the understory all have the ability to
sprout back after being topkilled. Some, such as Dhus
g oEllia, are prolific root-sprouters, but most sen! up new
shoots from the rootstock at the base of the stem.
generally, few shrubs are tilled completely by single fires.
Robertson (1953) recorded mortality of 0-10" in nine specie-
after a fire. Depending on the funl accumulation and
burning conditions, some fires may have no annarent Cfcact
on larger hardwoods. All the herbs arn perennials that
sprout back auizkly and seem to flower more profusely in
recently burad areas than in unburned areas. Some of t'is
apparent increase in reproductive activity may be lue to
improved visibility or more synchronous flowering, hut thcr
is no question that flowering of many species of grasses is
stimulated by burning (Robertson 1962).
The fire history of the rock ridge pinelands is difficult
to reconstruct with any degree of detail. The use of fire-
scarred trees is limited because of the small number of
suitable traes and the ambiguity involved in ring counts in
South Florida slash pine (Tomlinson and Craighead 1972, Arno
and Sneck 1977, Taylor 1980). The only methodology
available is to deduce from present-day fire patterns and
species attributes what might have occurred in the past.
Lightning fires are a common occurrence today and are
likely to have been so ever since the most recent emergence
of South Plorila from the sea. The lightning is pronuce-
during freqaunt convectional storms during the wet season.
The average annual number of lightning strikes reaching the
ground in the rock ridge region is 4-10 per km2 (Taylor
1980). The =ommon sight of single dead pine trees with
longitudinal fissures running down their bark is testimony
to the high incidence of lightning strikes. In Fverqlad-s
National Part lightning-caused fires accounted for 2P' o'
all fires ini 181 of the park area burned during the peri1-
1948-1979 (Taylor 1981). Almost all these fires occurr?!
within the wet season months of "ay to October (?ig. 3).
During this study (on Aug. 2, 1990) a small lightning fire
burned about 3 ha of pineland near one of the sites.
Egler (1952) assumed a low frequency of lightning fires
in southern Florida and felt that before the arrival o'
people the uplands were covered by broad-leafed forest.
Robertson (1953,1954), whose viewpoint seems to be
substantiate by more recent estimates of the incidence of
lightning--aused fires, felt that the vegetation pattern was
much as seen today. He also argued that the presence of
pineland an!aeics implies a long period of existence of this
vegetation type. Both agree, however, in suggesting that
the arrival of Anerindians about 2000 yr ago (Tebeau 19A3)
brought about a marked increase in fire frequency an' that
M J J A S O N D
J F M A M J J A S O N D
Figure 3. Monthly distribution of lightning-caused
fires in Everglades National Park and prescribed fires
conducted in Long Pine Key pinelands within the park (after
J F M A
most of thesa fires probably occurred early in the dry
season. The arrival of European settlers on the scene
probably r3sulti in an even higher fire frequency
(Robertson 1953,1954). Besides the obvious effect as an
ignition souc-c (or fire suppression agent), modern man has
other more subtle effects on the fire pattern. The lowering
of water levels by drainage starting in the 1920's has
increased tha time that many vegetation types are burnable
and therefore should increase fire frequency. Lowered water
tables also increase the incidence of severe droughts,
resulting in more fires ia organic soils. On th- other
hand, roais, canals, ani other cultural features form
firebreaks that impede the natural spread of fires.
Present xtent and Condition
The Iiami Rock Rilge pinslands originally covered th!
rock ridge from Iiami to near Mahoqany Hammock in rverglae0
National Park. Davis (1943, see ?ig. 2) estimated the
original area cvaered by pine forests to be about 72,900 ba,
although he stated that this was certainly an overestimate.
The area of the Rockdale soil series can be considered an
independent estimate of the original extent of the rock
ridge pinelands. This has been given as 66,700 ha (Soil
Conservation Service 1958) or 62,800 ha (Leightvy t al.
Today the rock ridge pinelands are almost restricted to
the confines of Everglades National Park. A 1975 survey of
pinalands ani hammocks in Dade County found only 2984 ha or
pinelands outside the national park (Shaw 197r). By 1079
the area had dwindled to 2429 ha (Metro-Dade 1979). Yost of
the pinelands have been destroyed for agriculture or urban
development, Oaly a few areas of pine forest outside of
Everglades iatioaal Park are likely to be preserve! for th"
foreseeable future. The Dade County Parks and Recreation
Department manages three properties with considerable arzas
of pinelani: Larry and Penny Thompson Park (100 ha), ",av
Wells Pineland Preserve (100 ha), and the recently acquired
Tamiami Pineland Preserve (25 ha) which has sandy soil
overlying the limestone (2. Washington, Pade Co. Parks and
Oec. Dept., pers. comm.). There are many other smaller
parcels of rock ridge pinelands in the southern part of the
ridge, but almost without exception they are heavily invaded
by Schinus terebinthifolius, a weedy exotic tree, and are
not properly maintained by prescribed burning (Loope and
Although the pineland fire management unit of Everglares
National Park is about 8000 ha (Everglades National Park
1979), plinimetry of a vegetation map of Long Pine Kev
(Olmsted et al. 1983) and topographic sheets of adjoining
areas show tiat only about ~650 ha are in fact pinelands (T.
:aprio, S. Fla. Research Center, pers, comm.). vven within
the park about 500 ha were lost to agriculture before the
land was purchased by the federal government (?art of th"
area known as the Hole-in-the-Donnt).
Today, therafare, less than 10t of the original rockland
pine forest is extant and under some form of management,
There is a very strong possibility that many of the plant
taxa endemic to the liami Eock Ridge pinelands will be lost
inasmuch as only 8 of 17 are presently found in 7verglades
National Park (Table 1).
Eversladesl national Park
The Dinelinds west of Taylor Slouch in "veralales
National Part, known as Long Pine Key (?ig. 2), are thF only
major area of rock ridge pinelands remaining today. There.
is also a suall amount of pinelann east of Taylor Slough
near the main oark entrance. The Loni Pine Key Din.elann
are dissactel by at least six major transverse prairies adi
contain more than 100 tropical hammocks. The pineland
vegetation is described by Robertson (1953), Loope mt al.
(1979), and 31msted et al. (1993).
Evergliles National Park was dedicated in December 19U7,
about the time that the logging of the pine forest begun in
the mid-1933's was finished. The pine stands fond today
are almost entirely second growth, representing the progeny
of Zcll trees. The initial park fire management police for
the pinelands (and the rest of the park as well) was active
fire suppression, in keeping with National Park Service
policy. This initially resulted in qood regeneration of
pine but probably also allowed establishment of larne
numbers of iardwoods and an increase in size of those
k park service study of fire in the park carried out yv
Robertson (1953) concluded that fire was needed to maintain
pinalands ani prevent succession to hammock. This led, in
1958, to Everglades National Park becoming the first park
service unit to use prescribed fire. Roads wer= construct-e
to divide most of Long Pine Key into ten management blocks,
Details of fire management are described by Klukas (1971),
Bancroft (1976,1979), and raylor (1981) and in the currentt
fire management plan (Everglades National Par'- 1979). After
the initial buris of the management blocks in the lat-
1950's it was often 10 yr before the next burn; since about
1970 the burning rotation has been shortened to about Fverv
5 yr (Taylor 1981). Until 1980 the prescribed burning of
oinalani was :arried out almost exclusively in the cooler
dry season months (Fig. 3). Since then many burns have be'n
carried out luring the lightning fire season.
Prescribe burning is used by the park service to reduce
fuel loads to "natural" levels and as a substitute for
"natural" fire where oresent-day conditions do not permit
the normal pattern of burning (Everglades National Park
1979). A liEficulty in carrying out this type of management
is that ther2 is no explicit sttaement of what constitutes
the natural stat,. Fires caused by indigenous people might
be considered as natural as lightning-caused fires.
It is quite possible that the hardwood understory in the
pinelands af !verglades National Park is today more
conspicuous than it was a hundred years ago. Logging and
the subsequent period of fire suppression may have changed
the balance between herbaceous and woody species. The
prescribed burning program has not significantly reduce the
amount of hiriwools from levels present when the program
began (Taylor and Herndon 1981).
RFperimental Design and Site Selection
Paired plots were set up at two sites
representative of the rock ridge pinelands of Long Pine Kev,
7verglades National Park. One randomly selected member of
each pair wa3 burned during th wet season of 1990 an~ the
other during the dry season of 1980-81. The burns ver-
intended to be is similar as possible except for air
temperature ind fuel moisture conditions, which vary
seasonally. Aboveqround understory biomass anr litter were
simple before burning, immediately postburn, anl at 2, 7,
and 12 mn after burning. The aboveground biomass ind
nutrient stocks of the regrowth vegetation were taken to be
measures of ecosystem recovery.
The sites wers chosen to exemplify both the higher, more
frequently barnel pinelands in the eastern end of Long Pine
Key, and the lower, less frequently burned pinelands to the
west. The choize was restricted to areas that had been
unburned fir a long enough period that sufficient fuels for
complete burns were present. Pineland managsennt blocks T
(site 1) anl E (site 2) were chosen as appropriate sites
0 0 0
I S. *
j r. 0 M-
SEl =M 0-
z Ow to)
-rl 0 01
Site 1 contains some of the highest ground in Longq ine
Key and hal been burned more frequently than any other
management block (burns in 8/57, 3/63, 2/63, 12/99, 3/71,
and 11/77). The shrub layer at this site was generally
below 1.5 i, with few hardwood stems greater than 2 cm
basal diameter, and there was a well-developed herb laver.
Site 2 was the least frequently burned management block
(burned 1/59, 4/69, and 1/75) and is in an area where th?
water table occasionally reaches the ground surface. The
hardwoods at this site were larger, often 2-3 a tall, ani
basal diameters of 3 cm were common. Solution holes are
common in site 2 and there was a less well-develooed herb
layer than it site 1. The pine canopy at site 1 was made
up of larger, more widely spaced trees than those at site 2.
The criteria for plot locations were that they ba arhas
of at least 3.5 ha with relatively homog0neons overstorie-
and understocihs. The plots (Fiq. L) were located near
roads (but > 5 m away) for ease of access and to simplifv
the development of firebreaks.
The burns were conducted at last 3 a after a rain when
conditions met the criteria of the park fire management
plan, including wind direction and air quality standards.
Prescriptions were kept broad to insure that the burns coul
be done close to the intended date. Fires were set on the
leeward siles of the plots because backing fires arp more
easily controlled and are less likely to cause crown scorch
in overstory pines than head or flanking fires. All burns
were conducted nier midday by the park resource management
Preburn faals ind the material remaining after the 'urns
were collected as part of the biomass and litter sampling.
Wine-fuel-m3istrwe samples (material < 7 mm diameter in 0.25
m2 quadrats) were collected during the burns and dried at
7003. Relative Eire temperatures were measure with plates
placed at ground level, 0.5 m, and 1 m on 12 poles at pos--
burn sampling locations. The plates were made by spotting
temearature-sensitive paints (Tempilaq, Tempil Div., "ig
Three Ind.) on steel plates (75 X 130 X 2.5 mm, 250 7).
The paints had maltinq points of 52, 70, 93, 1'1, 121, 1 ,
149, 177, 203, 232, 263, 298, 302, 316, 343, 371, 3o1 427,
and 45 oC according to the manufacturer's soncifications
(but see 9obbs et al. 1984). The large mass of the Dlates
tends to depcess the maximum temperature registered by the
melting paints so that they more closely reflect
temperatures experienced by the heavier vegetation rather
than maximum flame temperatures. The resource management
staff measuraS ambient air temperature, relative humi'it7,
wind direction and speed, and rate of spread. "irelin-
intensity was calculated by assuming a heat yield of 14,000
kJ/kg of fuel (Wide 1983) and using the following equation
(Brown an? Divis 1973, Wade 1983):
I = Hwr
where I is fire intensity in kW/m, H is heat yield in kJ/kq,
w is mass of fuel consumed in kg/mn, and r is rate of spread
of fire front in m/s.
Atbs2erounl Mass Samoling
Vegetation anl Litter
Abovegrouid understory vegetation and litter were
!sstructively sample! for rry mass. The sampling was don=
in 60 X 80 m plots (0.u8 ha) subdivide! into 12 20 7 20 a
subplots. Within each subplot, potential sampling
quadrats were arranged in a grid pattern. At sito 1 there
were 16 2 X 2 m guadrats and at site 2, nine 3 Y 3 n
quadrats available per subplot. 4t each sampling period two
randomly chosen quadrats per subplot were sampled at site 1
and one quicrat per subplot at site 2. Therefore,
approximately equal areas were sampled in both sites, but
larger qualrits in site 2 plots were used to reduce between-
guadrat variance. Buffer strips 3 m wide between quadrats
permitted movement through the plots without disturbing
l11 plants ware clipped at ground level exceDt palms
which were clipped at the base of the petioles. In LonT
Pine Key Sibil aLimett, anid occothrinax arqentata usually
have little stem projecting ab-ve ground, and although the
horizontal, creeping rhizome of Serenoa reo-ns is often -on
top of the rack substrate, it is generally unaffected hb
fire and is Eunctionally much like a belowgronnd structure.
Shrubs and palms were collected from the entire quadrat.
eHrbs and litter were harvested only from 1 7 1 m quadrats
nested in tha nW corner of the larger shrub quadrats. Tn
the site 2 plots, herbs and litter were sampled from an
iiditional 1 X 1 a 7uadrat in the S7 corner of the shrub
gaadrat beginning with the 2-mo postburn sampling. Pinp
seedlings were counted in the herb and litter quadrats.
Litter was defined as any dead plant material
iientifiable as to origin, essentially the L and 7 forest
floor layers of the older forest soils literature F(ritchett
1979). generally there is little humus material (U lav-r)
present in Long Pine Key pinelands because of frequent
fires, but in site 2 especially there were occasional
pockets of well-3ecomposed plant matter. A prominent part
of the litter after a fire in these pinelands is the
standing deal hardwood stems: these were sampled from the
entire shrub aualrat. Dead palm fronds were included with
forest floor litter in the 1 X 1 m quadrats as were any pipe
needles draped in the understory vegetation.
The harvested material was sorted into various
compartments, iried at 700C to constant mass, and weighed to
0.1 g. Shribs were sorted by species; leaves (plus rarely
occurring reocodnc:tiv parts) were separated front stems For
the preburn, postburn, and 12-mo sampling periods. PatioleT
ware not separated from blades of palm leaves. Herbs were
treated as a single compartment although record was keot of
all species observed in each plot. Litter was separated
into pine aia non-pine components. In the prbnurn sampling
only subsaomles of litter were separated and the
proportions were applied to total dry mass. At later
sampling periods pine litter was further subdivided into
needles and other pine and the non-pine litter was
categorized as herb litter, forest floor shrub litter, inl
Por nutrient analysis, vegetation and litter from three
adjacent subplots were bulked by tvoe and a large subsamle
kept. In general the categories were the same as those
reacrded for mass, except that only two or three of the most
important shrub species in a given set of subplots were kept
separate and the rest were combined.
The diameters at 1.5 m (dbh) and height of all pine trees
in each plot were recorded along with the number of standing
dead trees (snags) and stumps. Regression equations from
the literature were used to estimate biomass of the
Accounting for the mass and nutrient content of the ash
following the fires posed a special methodological problem.
The ash was :ollaetel by two methods. The first consist-e
of placing four Petri dish bottoms (9 cm dia., 21 mm dlpth)
under the litter before the burn at 12 nostburn samnlina
locations (oae in each subplot). Immediately after the
fire, covers were put on the dishes and they were taken
back to the lib. The contents of the four dishes from each
location wera caobined to form a single sample. The
aivantag2 of this method is that the samples can he
collected as soon as the fire front passes; a sudden rain
does not prluale sampling. The disadvantages are the
relatively small area sampled and the difficulty in nlacina
the dishes uader all the fuel, especially in an area wit- a
substrate as rough as Miami oolite.
The se;Bon method was to oick up the ash with a small
vacuum (Car-Yac, Black and Decker) powered by a 12 V
battery. At the same 12 postburn sampling locations a I.?
m2 area was vacuumed and the material was transferred to
plastic bigs. This method cannot be used once the ash is
wetted. It is very effective at picking up all the ash, but
there is potential for contamination with soil. 'oth tvpes
of ash samples were analyzed individually for nutrient
content, although N was measured only in the vac-um samples.
The contribution of the pine overstorv to 1indrstor7
littermass and nutrients was measured by collecting
litterfall for the 12 mo post-fire period. Dine needles,
bark, and male cones were collected in litter trays
(galvanized greenhouse flats, 0.187 a2, with drainage holes)
placed two per subplot in each of the treatments. Trays
were also put out in an unburned area of site 2 to see if
burning increased needlefall. The trays were emptied at 2-5
wk intervals inl material from three adjacent subplots was
pooled to give four samples per plot. The litter was ovpn
dried (700:), sorted into needles and other fine pine
material, aid weighed to 3.1 g. All other material was
discarded. The input of larger material which is
inadequately sampled by litter trays (branches and s'ee
cones) was measured separately at both sites. All newly
fallen (un=hicrri) material was picked up from a strip ?.5 r
wide outside the dry season burn plot borders twice during
the year after burning. Collecting was done in 20 m
lengths, resulting in 14 50 m2 sampling areas. Brarcher
were separated iato 1-cm diameter classes before oven drvin7
and weighing. I assumed that branch and sepd cone
litterfall was tie same at both plots in a given site.
Needlefall was bulked by plot for a drv season perio.
(Dec.-Jan.) for nutrient analysis because these samples were
least subject to leaching losses while in the litter trays.
The total annual fine litterfall (mostly bark) was bulked by
plot for analysis. The nutrient content of branches and
seed cones was measured on material that fell during a 77 ,1
period lurinj the dry season at the site 2 dry-season plot.
materials from the (three or four) sampling areas on each
side of the plot were combined and subsampled to givP four
samples of each type. The nutrient concentrations of the
2-3 cm branch class were applied to the small amount of
material larger than 3 cm diameter.
Two types of soil samples were collected to characterize
the surface soil (0-7.5 cm) and to detect changes in soil
properties prassat 12 mo after burning. The first type was
samples take from the preburn biomass quadrats in all tho
plots and from the 12-mo quadrats in two of the plots. "en
scoops were taken with a trowel in each subplot and then
bulked to form 12 samples per plot. The sampling spots wero
soaked as evenly as possible in each guadrat, but
considerable searching in cracks and crevices was often
required before a scoopful of soil was found.
At site 1 areas of refdish-brown mineral soil were
encountered La the preburn soil sampling: these araas were
readily apparent after the burns. The extent of these
pockets of "Redlind" soil in the site 1 plots was estina+ed
by line-intercept along the 20 m borders of all subolots
(n=31 in easi plot). Because the preburn soil samples wero
heterogeneous with respect to the type of soil sampled, a
second sampling restricted to the Redland soil was done.
oomoosite samples of 10 scoops of mineral soil froa
throughout each of the subplots in the site 1 Iry season
plot were taten 12 m3 after the burn. In the adjacent area
which harnel 5 yr previously composite samples were
collected in a similar manner along 10 m segments of a 120 m
transect. 411 the soils were dried (700C) and sieve~ (2 mn
screen) before analysis.
Tissue and Soil Analvsis
Subsamples (0.5-1 L) of the bulked vegetation and little
material for chemical analysis were ground in a largP Wilev
mill, thoroughly mixed, and store- in polvathvleno bottles.
The ground samples were retried at 700C before wigqhinq.
Nations (Ca, "g, and K) and P were measured on 1.i0 g
samples placed in 50 ml Pyrex beakers and ashed at 5000C for
at least 3 hr. The resiane was dissolved and then brought
to dryness first with 5N HC1 and then concentrated !Cl
before filtering (Whatman No. 42) and bringing to 50 ml
final volume with 0.1 R C1, Calcium and ng concentrations
were determined by atomic absorption, K by flame emission,
and P by automated colorimetry (Mitchell and Sh',? 1979).
Nitrogen was analyzed by a micro-Kjeldahl procedure usia7
0.500 g of litter and stem tissues and 0.250 g of all other
materials. lamonium was determined by automated colorimetry
(Anonymous 1977), The cation and P content of the postbhrn
ash was determined by similar methods except that the
residue aftec fishing was dissolved in larger (107-20X)
volumes of acid because of much higher nutrient
concentrations. Following Kjeldahl digestion of the ash,
ammonium was measured by distillation and titration.
As a chaek on analytical procedures, replicates of a
single leaf tissue sample were run with each set of dry-
ashed s3mples. The ropliration was good, with co-ffici n's
of variation of 4.0 3.57, 3.0O, and 2.u' for K, Ca, "7,
and ?, respectively. recovery of K, Ca, and P from four
samples of Nitional Bureau of Standards pine needle tissue
averaged 81X, 1181, and 98% of the values listed for these
elements. There is no published value for 'g. The 7.,.S.
pine needle tissue was run with each set of Kj1ldahl
analyses and always was within 35 of the nominal value,
Soil pH was measured in a slurry of 25 ml of soil an! 50
ml of water eguiLibrated for 30 min. Organic matter was
measured by the Walkley-Blick vet oxidation method on 1.0 q
samples, Citions and P were extracted by the double-acid
(0.05N HC1 3.025N 12504) method and analyzed as for plantt
tissues. Details of methods are found in Mitchell ana Phua
initial _Veetation Structure
Pins elliottii var. densa was the sole canopy tree
species in all the plots. Both sites had apparently been
logged not long before the establishment of the oark;
numerous stumps still remaining have resisted iore than 11
yr of exposuca and several fires. The density of pinp traes
at site 1 was about half that at site 2, but the mean hasal
area per tree was about twice as large, so total basal area
at the two sites was similar (Table 2). The trees at si'- 1
were also tiller than those at site 2. "any o' the larger
pines at site 2 had misshapen crowns and probably represent
There weca very few pine saplings (< 5 cm dbh) at site 2
and none at site 1 (Figs. 5-7). There were also very few
pines <1.5 m tall that had grown out of the "grass" stage at
either site. Before the burns site 1 had 1.2-1.5 seedlings
(no stem Plongation) per m2 and site 2 had 0.1-0.3 fTahbl
k total of 12q taxa wers observed in the plots during the
course of the study (Table 3, Appendix A). This is a slight
underestimate of the number of species present because some
SE m CN co in
4- a a co o
0 -4O H
0 0 i-
4Ja 1- vm
*0 --a r in in I
0 Z D m C\ m cN
IN M -
oC 0 in I N 0
4J- .0 .
4-z il E!a H m r ;
0-4 a '- IN IN -i -I
(a0 H M * C C
(4 40 (N CN m n
4- ) 0 o 0-
0 0 m a
4M Gr11ia aT in IT in
U) M # + Cm LO i-T 1
0 0 0
0lu o o
S O O B
4j (a 0 a'a'a.o 0 m
la) a m ) m ) o m r-
'a e 4-1 -H a
n 0 M o n m
0 5 10 15 20 25
OI 5 BURN
-0 -15 20 25
0 5 10 15 20 25
DIAMETER CLASS (cm)
Figure 5. Size-class distribution
the site 1 plots.
of pine trees in
45 SITE 2
0 5 10 15 20 25 30
Figure 6. Size-class distribution of pine trees in
the site 2 wet season burn plot. Unshaded bars represent
trees dead at 1 yr postburn.
0 5 10 15 20 25
Figure 7. Size-class distribution of
the site 2 dry season burn plot. Unshaded
trees dead 1 yr postburn.
pine trees in
4 -1 ) 0
uau Umanne co
r-I m r- -p in (N
HIfl 0(N 0
^ ^pr^ f rim ~ o C
Ea 'o >1
0 Ea (a In 0 aa 0
ED U 4-0 4- 41 4-
a) 0 -I 3 > r r a
uncommon spazies were probably missed and because a few
herbs were identified only to genus. Within the herbs the
Asteraceae, Poaceae, Euphorbiaceae, and Fa'acea- were
particularly well represented. ?ive shrub species arT
members of the Babiaceae, which contributes an additional
four herb species. Other important shrub families
reflecting tie tropical origins of the flora include the
Arecaceae (piims, 3 spp.), Anacardiaceae (4 sop., including
one exotic), Sapotaceae (3 spp.), and Myrtaceae (3 sup.).
The overall soecits richness dii not vary much hetve-n
sites: however the site 1 plots had higher herb speci-s
richness and the site 2 plots had higher hardwood species
richness. This pattern may be due to characteristics of
the substrate and the close association of the site ? olnts
with hardwood haamocks that aan serve as seed source's: it
could also be due in Dart to more frequent burning o' site
1. Some herbs in site 2 are restricted to the w=tter
microhabitats in solution holes (e.g. Cladiun jamaicpnse
and Thelzpteris kunthii) and some grasses and sedoes at sit"
1 seem to be found only in the patches of ?edland soil (e.g.
hznchoshEorE a E bulais and Desmodium lineatsm). The
hardwood species found in site 2 and not in site 1 are
mostly species characteristic of lower, wetter areas (e.g.
chersobalanus icaco and Ilex cassino) or species found in
nearby hammocks (e.g. Ccccoloba liversifolia and Ivsiloma
The pine overstory clearly dominates the vegetation in
terms of bionass (Table 4). The understory vegetation, in
which the hardwoods are the dominant component, made up 6f
or less of tie total aboveground biomass. The understory
vegetation is much more important in terms of nutrient
content because so much of the overstory biomass is wood,
which has low nutrient concentrations.
Although herb species richness was due largely to forh
species, grlminoais in general contributed more to hbrb
biomass. Prominent grasses include Schigachvria rhioemat'li
(a South F.icida endemic) and An rop2aon cabanisii. Tho
major exception to this was occasional patches dominated by
the fern PtEriLm aguiliaum at site 1. The relative
dominance of the understory shrub species as expressed by
percent biomiss is shown in Figure 8. Puettaria scg-hr wpa
the lominint species at both sites, but less so a+ sit= '
where there were more species. At site 1 Dodonaaa viscose
was the second most important species, a position held by
Evrica cerifers at site 2. At site I the top two species
account for about 55X of the shrub biomass, and at site 2
only 41g. The palms Sabal nalmetto and Sgrenoa renens are
among the top ten species at both sites, but S. reoens is
more important at site 1 and S. palmetto at site 2.
occzothriqnax ar ntata is rare at site 2 an' is nuch less
important than the other two pals at site 1. The biomass
relations of the palms are a reflection of their densities
* m-1 0
' 1+ 1
re Mh Ln
+ In 0
C 0 O
0.0 I I I I I I
I 5 10 15 20 25 30 35
Figure 8. Dominance-diversity curves for preburn
shrubs in the study plots. Circles = hardwoods, squares =
palms, and triangles = Zamia floridana. Site 1 plots are
represented by closed symbols and site 2 plots by open
at the two sites (Table 5). Zania Epuila had the eighth
highest preburn biomass at site 1 but was rare it site 2.
The wet season burns were carried out under conditions of
relatively iigh ambient temperatures and humidities,
although the nfel moisture of the site 1 wet season plot was
as low as the dry season plot (Table 6). The site 2 vet
season fuel was such moister than the dry season fuel.
All four burns resulted in 100? topkill of the unacrstory
vegetation, wita minimal canopy scorch. About 707 of ''=
fuel was consumer in the burns except for the site 2 wet
season burn in which high moisture content reduced
consumption to about 50%. The ash resulting from the burns
formed a thin, discontinuous layer on the cock surface un'il
the first posthucn rain washed it away.
The rate 3f spread of the fire front was less than 1.5
cm/s arcapt for brief head fires during wind shifts in the
site 1 dry season burn. The intensity of the burns was
within the optimum range far prescribed fires (73-260 kW/m,
Wade 1983) recept for those brief periods in the site 1 ric
season burn that resulted in the scorching of about 10 of
The averij3 fire temperatures recisteres by the
temnerature-sensitive paints varied significantly aeong t'=
burns (Table 6). The site 2 dry season burn, where the
0 re 4 o 0 aD ew
S0 M N Ni m
4-4 o Ql r
4- U 0 4-)
O r u -1 CU
o 0 H c 4-1
Ou O o o0
04-) C)4-.) (E 04 O U) ev
0 ft 0 U o uo m
'0'0 ,-i m C ) CD
C'o aC) -i
U) : 4-1 H- ( .
fo a, (1) (o
4-W Q4 W
0 U r-I 4)
.(-1 0 0
ol Un 04 a 1)
S-i ( 4 co Lfn )N iLn
4J1 4-1 (D
0 *H 4-1
0) C0C 04 Ln m a
r- a) an m r
0O En Cv
0 4- 0) Q
-4 > (0
ll Q) N 0
S0 0 04
O.4 0c r P: 0
Q 40 a d)
a)~U a I o -ic
O .i 04
14m M 4.
>1 CN H
-4- ) 00 0 a)
04 D0-- O r-I
0 O *
l rO J 4 -H1
rd-H tW (a
SrlC V I
C -1 4+ (a
En -H X 4J L4
0 4 -1 En
H 0 Ci
V U0 0
dB rO *CC7
o 40 -ri -H OH
O1 00 4- 04
O4 rd O
0 1 >) 0
-I -r) c 0 -4-r
3 > 10 C C 0
-ri 4 o En M N
4 0 -H>c
U rl 34JU 04
En 9r- Qa) +; FO
) (0 ) 4 0
Q N J- CO U
a\~ 0r n
r- L m f
mr fiir -
greatest amount of fuel burned, had the highest
temperatures; however, the ground-level temperature was not
significantly different from the site 1 wet season burn.
The ground-level temperature of the site 1 dry season olct
was lower thin the w-t season plot, probably because of
lower ambient temperatures and the more rapid movement of
the fire over th? plot. Temperatures decreased with height
above the grannd, although this pattern was least pronounced
it the site 1 dry season burn.
Fire -ffects on gUn.erstory ass and Nutrients
Initial )istcibution of Mass and Nutrients
The relative Jistribution of the preburn fuel mass amonq
live understory vegetation, understory litter, and pine
litter was similar in all four plots (Figs. 9 and 10). ?Pi.
litter account-3 for 50-70L of the mass and liv2 vpegtation
for 251 or less. The distribution of N and Ca was similar to
mass, but Mg, P, an3 especially K wero relatively high in
the live vegetation. In fact, 75-80 of the K in the fu1e
was containal in the live vegetation. Potassium is easily
leached and gaickly lost from dead tissues. Within the live
vegetation hardwood shrubs were responsible for > 507 of the
mass and nutrients, more so at site 2 which had not b'rne~
for a longer time.
N zZ I
Ash Collectian methods
There were no significant differences between postburn
ash colleztipn methods for mass, nutrient concentrations, or
nutrient staiiing croos in the site 1 burns with a single
exception: liighr 3g concentration by the Petri dish methfo
from the dry season burn (Table 7). There was, however, a
consistent pattern of higher mean nutrient concentrations in
the ash collected by the patri dish method. A light rain
falling near the end of the site 2 wet season burn proclud=d
the collection of ash by the vacuum metho feor that hurn.
In the sita 2 dry season burn the estimates of ash mass ani
all nutrient standing crops were significantly higher for
the vacuum 2eth3]. The tendency for higher nutrient
concentrations in the petri dish ash was also found here,
with only Mg significantly higher. Apparently at site 2
substantial aaounts of unburned humus and/or mineral soil
were pickz1 ap by the vacuum. This would account for bo+h
the higher mass and the tendency toward lower nutrient
concentrations. Because of the larger surface area sampled
by the vacuui method, it produced smaller coofficients of
variation for mass and nutrient concentrations in 14 of 15
The dry mass and nutrient cationss and P) values froi the
patri dish acthoi were used to estimate postburn starling
crops because they were available for all the burns anJ
because vacaui samples gave over-estimates at site ?.
**>o N *T i^ co
fC N- 0 o 9C 9 0 0 0 00 N CN N -
C N C ( N *
0 O 0 0 0 0 0 O x a a t s 1
0+ -H -+ i +1 +- +1 N - (N
0 + a N Nn aN N
44 II ^ Ci f r M 1 + | +| +U 01 9 0 0
C .. m ,o
02~~N .9 U, U, 0 N
Q) 4 JI,,,
0 - - -' (N ^ N 0 U N U
Cn > I-9
Wc 104 .
U 0 o -N O 0 N0
QJ o Ao *m rs N
H C N N n N N N E I 9 .9
64 C N N U, N UN N N 9U, U, (N
CC + 0 z4 - ( N c f
0' -, +r +9 +| +9 +9 +9 -
HC (0 N U N -
Hi- C -l P- N N N( U 0
o 0C S o
C," o1 f^ n 3 m in CT\ ^i o 01 O
0, N (Ni N N N N 9 CCT C .
02 Cj - (N 0t (Ni -- C 9 +9 + + 9
tfl ^ 0 0 0 N O N .
rlCV cl I n p^ ,- 01 3 n f d o o
S . . + 0 U N
4 '. 9 a 0 C C C IO^
(U U > U U -< n (N + U, (
024 ^J (N N (N (N (N NI (N +4
S0 09 C0C N 0 0 O
4444 N N 0 N N (N NU
02I N N) N N N (N (N D a O
NJ No 0^ '' -' N N
+91 S N 19 0 .9 0 N .9 N .9
020 9 '0 &
02 i 0 I .9 I I CM ++ N +l (N U, +
Qi Z 1 0 0 9D 03 -9 NU N ND U, N
N O l +i N +i l9 I M [- l n m o 9 9 + (
O 0 N U,0
(9 NN N U U N ON C .
E N U N U IF 9~ 9 NI
'C) ., 42 o 2 2 *I
0 u +9 +9 + +9 +i +0 +9 U, m (N
I+iO N NP N^ No N- (N N- +9 o 0 +9
aO U, N N N N 9+ U,
9+ (N .90 (N
(N Nl 0 U . -o- c
aC >uIC +9 +9 +9 N N N -
(990. Ul U,' NO N NO M (NO.9
02 Q C ) I r CT co ul r~
C0 U'' C U' '
-j02 .9 C) C +9+9) C 0 -5) E e C
+9 +f1 Cr '4 14 C CCC + .9 +9. 39 C C
. -i ,? U' C^ E' C^ N*- U' C" U ^
rl ., I- I 3 D -
a vll X: E. +I U J U +1 *
024 w '9 '9
04 in r a u
fa n3 o
00 C U
C (99 +4 J >. +9 .99
C' .9 3) +4 ii) 04i
~ 3 n 01 3 CJ 3 kj
H O C)I +9 -I -IU +IL
r^ oa a Q
.fl +9 (N (N +
02 .4 E .
Nitrogen in ash was estimated from the mass an? nutrient
con7entratioa data collected by the vacuum netheo. Since
these data iare not available for the site 2 v t season
burn, the meB n J concentra ion for thm site 2 3rv s-ason
burn was applied to the wet season oetri dish estimates of
ash mass. Tie estimate of N in the postbcrn ash at tbh sito
2 dry season burn is undoubtedly an over-estimate and
thicefors qi4?s a conservative estimate of the loss of for
Postburn istribhution of !ass anj Nutrients
lost of tie litter (except for the heavier pine branches
and cones) was consumed in all tho burns (iqs,. 9 and 101;
in the site 2 wet season burn considerable amounts of th?
oartiallv lo3ompos lovwr layers of litter in '~oressions
wrea also left. Yost of the preburn vegetation di- nomt qrn
ercept in the s[ta 1 wet season burn where sliqhtlv morn
than half wvs consumed. Herbs were almost completely
consumed in the burns (exIcpt for petioles of teridiun),
but shrub stams ian most leaf material remained. The shrub
stems that remained upright became the standing dead
compartment of the nostburn litter. The blad-s of paln
fronds were often at least partially consumer but the
patiolbs did not burn. rhe 78-95 g/mn of postirrn ash
accounted foc 9-2;- of the mass remaining after the brrs.
The losses of nutrients from the litter and vegetation
were roughly proportional to the losses in mass (pies. 9 anP
10). one-haLf or more of the standing crops of the non-
volatile elements other thin K were found in the ash after
the burns. A large proportion of the K remained in thi
dead, but unconsumed, vegetation (mostly shrubs). The
nostburn distribution of N was similar to the nosthurn
distribution of mass.
The overall losses of organic natter from the ecosystem
ranged from bout 1-1.5 kg/m2 (Table 8). The losses of 7
ranged from 5,7-9.5 /ma2. There were no sijnificane
differences between preburn and postburn standing crons of
the non-volitLle elements except for a loss of K in the sit?
1 wet season burn. This represents one of 16 tests (at 0.0~
level) for nonvolatile nutrients and may bh a falss
rejection (i,e, a tvoe I error). There is li'tl- re:-so '
exoect detectable losses of K in relatively cool fir-s sIuch
Postfire Pecoverv of ahss and Nutrients
Although abovaground plant parts were killed hv the
burns, I observed almost no plant mortality. r'e of *he
most striking feitur-s of th= postburn period was the rail
reappearance of green tissues, especially herbs anl nalis.
Within days aftar the burns fresh blades of grass apnear"-
c0 -rHl t r H0 f fl-I 4CN C'i0]'0 f l'LAC 1C r-4
-1 0 y-4 P 000 o0- r- CNN O- r-1
0 0 ( 0) *n o M . . .. .
T 54 >4 rWH -Or 000 000 a 'N CC 000
0 0 n +1 +1+1 +1+1+1 +1+1 +1 +1 +1 +1 +1+1+1 +1 +1 +1
Sd Q W0 n n 0CN me -e1 N -A Ln fl
aNiLn mClo :1;o . Lo
0 .*>i m n o mmo * * mn ..
rr ~QH r i 000 HH- NN I CN -0C
0 020 4
4. C-C CCNO0 000 i-irl(N NMWo O0mt
C 4VC m t0 n . . . . . . . .
0 +1 +1+1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1
O +1 4J 3: 0)oC r43 m a- 0 0 %D 0cr- CN ) .N
C 0 * r-0 1m- *** NNO
0 0zm a a **0]) 0 o * **
024Jn -1 00 C -4-4 40 C-C C -NC)J
Ud ) H O H O NN NNO
rO tp n3
0 c 0 P-4ro ri i N o or r- r- OD~ w r %o00
[ fa0 r o ** C D .. .
4 >4 qnv 000 000 3ooo Coi4 000
0 o 0 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 + +1I +1 +1 +1
1C m M -4 C- mmC0- L* ** No 0mmi r 00o-
If I] r.. 0000 rz--p . CN Or lC O
c 000 000 O 000
40 -l a) *
-H o -4r
0C 0 10 --4 rH- w )-4
44 OI 4- 000 r-(m mom m3Crn 0om1-
C- 04 00 0 000 -4o- oNc 00 -i
4 4J 4 UO N m 0 0 0 0. 0 0
2 4J -4l Q 1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1
00Q) 4-4 COOD CfwrD m00zzp oVwLf-i 0Oi 0m r-im 1--
0a r* C- NCJO Mc *o nO
S> z i- 000 -4 r-I0 r- r-I -O 0
14 C -H
4 14CS- CC4 C14 Ce c -i
m Ul -U w1 p;3 01 H :: 3 Pi 3 M H :J U) t 3 01 : 4 3 V2
U 2 na C 0 3Cf 0 0 2C f0n -0-:(a -H30 3 E3 0 2 -Hi l0a
0 2a r02 O 4 0 .2 4- 0 434-C +0 02 f O 30.0 41 0 M 0 2 l0O
02 Q -H 02 4 0 W (n-? a ) m 0 2 w n w00 m -H0(D(a- (a 02 ww
i o o i o 0B 1440 p 0 CU 1o 00 0p0 Zo40
.0 >iO C-0. 4- Hi PI PO p0 4- A. PC r-4 l P4P tnP4 P4
10 1 C -HJ C 0 n0 r0
CQ C Q Z P. U U
from the ground and palm fronds pushed out from the stem
oices. f arwoon recovery began somewhat later.
Essentially all the recovery during the first year was
ieu to snrouting from belowground parts. Among the
hardwoods only Dodonaea viscosa and Rhus sooallina hai any
seedling regeneration, but this contributed an insignificant
amount to tta total recovery. The seedlings probably came
from seeds present in the soil or litter before the iurnm;
both genera are known to have fire-stimulated germination
(Ploy 1966, larks 1979). 7o data on reproductive activi'v
were taken, 3ut luring the year following brr.in7 I o'bserv
flowering of every herbaceous species Dresent in t'he plots.
Within a aoith after the site 1 wet season burn inellia
caroliniensis was flowering and by 2 mo 15 aliitional
snesies were in flower. productivee activity of palms was
not noti.Ze-bly different in bu n unbrn ai na? ar as. Mo t
hardwoods dil not flower during the first year after %rning
except for t1e weakly woody Lantana devrossa, 1orinda rovoc,
and Zcoton line ris. Occasional individuals of Psidium
lon2!ai2S 3lrsonima lucida, Iodonaea viscosa, anI Ficus
zitrifolia also flowered within the first year.
Harbs reached their preburn biomass levels within 7 mo
following dry season burns and hy 1 yr after wtt season
burns, even though the 2 mo recovery was grea +r after wV
season burns (Fig. 11, .ppendix B). In all four of the
plots palm biomass by 7 mo was statistically
indistinguisiable from preburn amounts. Hardwoods recovered
more slowly than herbs and did not approach their preburn
levels by thE eni of the first year. Recoverv a' 1 yr
ranged from 19-39' of the orebturn biomass, Certain hardwood
species sprouted sooner than others (D. viscosa and 2.
c2Eallina wece two of the earliest). Hardwood biomass
increased at each of the sampling periods following wqe
season burns, but showed no increase from 7-12 mo after th
dry season barns (Fig. 11). The overall pattern of r;coverv
indicates that koril to August is a more favorable qrowi-r
p~riol than the rest of the year.
Before the fires, stems accounted for most of the
hardwood biomass, whereas 1 yr after burning leaves
accounted for equal or greater amounts than stpas (Appendti-
3). ar.wn33 Leaf biomass recovered to 32-68- of t.h
prehurn biomass but stems reached only 12-2' oi' *he
original amounts. The preburn stems, of course, represent~?
the wood increments of 3.5-6.5 yr of growth.
The relatively rapid recovery of leaf biomass combinoI
with complete recovery of herb and palm biomass means that
the functional capacity for photosynthesis recovers faster
than tha structural characteristic of biomass. If ons
assumes that the sum of herb, palm, and har-wood leaf
biomass is a measure of ph3tosynthetic capacity, then t"- 1
yr recovery of the vegetation for wet and dry season burns
is 82 and 93t at site 1 and 74 and 58' at site 2. The
corresponding recovery of total vegetation biomass
(including hardwood stems) is 55, 63, 41, and 27?.
The above7rouad net primary production of the unerstorv
for the first veir after burning can be estima-ed ty adding
the litter produced during the year to the standing crop op
biomass at the and of the year. There was no palm leaf
litter an! little hardwood leaf litter produced during the
first year, iad this litter was not measured seoaratelv from
the hardwood litter resulting from the burns. There were
substantial amounts of herb litter produced hv I "r
(11.7-39.5 I/a2, Appendix B). Fstinates of not production
are 156 and 166 1*m-2+vr-I for wet and dry season turn plots
at site 1 ani 20) and 144 g*m-2*yr-l for wet and dry season
burn plots at site 2. In addition to the few hardwood
leaves shEt1 y 1 vr and the loss of mass by herb litter
through leaching and decomposition, herbivor' is also not
accounteS fcr vb this estimate. Grasshopnprs anq
lepidoptcran larvae were the most conspicuous invertebrate
herbivores; the caterpillars of the echo north (Sqirarri-
echo) grazea the young leaves of Zamia Eamila vary heavily.
I also witnessed four white-tailed deer feeding on the voung
regrowth of 3a0 3o the plots.
Because tie herb and palm biomass 1 yr after burning wr-'
not significantly different from their preburn values, th=re
is little evidence that the season of burning had an effect
on their recovery. Variability in the data nake it
impossible to detect small differences that miaht have a
cumulative effect after several burns.
Rardwoods, on the other hand, showed arkd differences
in recovery among the four plots. The absolute recovery of
hardwood bianass was greater at site 2, but that site had a
nmuh higher initial hardwood biomass. At site 1 the
hardwood recovery was significantly lower following *he wat
season burn (29 ;/ma or 20) than the dry season burn (f?
g/m2 or 39f). At site 2 the trend was reversed, with
greater recovery after the wet season birn (137 7/m2 or I"1)
thin the dry season burn (78 g/m2 or 18!) Th? most~ li'=lv
explanation for this apparent inconsistency is that fire
temperatures had a greater effect on recovery than season of
The recoverv of nutrients in the undzrstorv veetation
followed a pattern very similar to that of biom~ss ficn.
12-16, Appealix 5). The maia difference was the somewhat'
faster rate of recovery because of elevated nutrient
concentrations in the young regrowth tissues. The recovery
of Ca, however, was delayed somewhat relative to biomass
because the 2 io tissue concentrations of palms and
hardwoods were lower than the preburn concentrations. Herbs
in particular often reached preburn levels of nutrient
standing cross earlier than biomass. For exarple, ?
standing cron in herbs was not significantly diff-rent fro?
the preburn amount for both dry season burns at only 2 mo
S I 150
12 0 2
Figure 11. Postburn recovery of understory biomass.
Bar on left shows preburn values.
12 0 2
Figure 12. Postburn recovery of nitrogen in understory
vegetation. Bar on left shows preburn values.
0 2 7 12 0 2 7
0 2 7
EASON DRY SEASON
12 0 2 7 12
SON 7 DRY SEASON
12 0 2 8 12
Figure 13. Postburn recovery of phosphorus in under-
story vegetation. Bar on left shows preburn values.
12 0 2
Figure 14. Postburn recovery of potassium in under-
story vegetation. Bar on left shows preburn values.
[1 - - -
12 0 2
Figure 15. Postburn recovery of calcium in understory
vegetation. Bar on left shows preburn values.
0 2 7
OTHER WET SEASON
0.35Z SHRUBS BURN
< 0.10 HERBS
0 2 712 0 2 7 12
0.788 SITE 2
0.40 WET SEASON 1 0.737 DRY SEASON
0 2 7 12 0 2 8 12
Figure 16. Postburn recovery of magnesium in under-
story vegetation. Bar on left shows preburn values.
postburn; thi standing crap of K in herbs in the site 1 wet
season plot also reached the preburn level by 2 mo. Tn one
case (Ca, site 1 wet season burn) the standing cror was
significantly higher 1 yr aftar burning than before th-
fire. For palms, both N and P standing crops were not
significantly different from preburn at 2 mo for the sit- ?
wet season burn. All other palm nutrient standing crons,
like palm biomass, dil not rcach initial amounts until 7 mo
The pattecn of recovery of nutrient stanlini crops in
hardwoods was the same as for biomass except thit K at 'lh
site 1 dry season plot at 7 mo and the site 2 wet season
plot at 12 no were not different from the prpburn amounts.
The percent recovery of all nutrients in hardwoods at 1 vr
was greater than th? corresponding biomass recovery tecausn
of hiTh nutrient concentrations. The Dercent recovzer7 o
the total -veg;attion nutrient standing crops was greater
than the reco7vry of biomass for the same reason. Th- t
standing crops in the two dry season plots at 1 vr ware not
significantly different from the preburn standing crops,
The standing :rop of litter sass (and nutrients) iurin-
the 1 yr postbura period is a function of the amounts
present immediately after the burns, inputs, and losses
through learning and decomposition. Even though nearly all
of the preborn understory litter was consumed in the burns
(Figs. 9 ind 10, Appendix B), the understorv vSgatation that
was killed bat not consumed by the fire replace, it. In th?
dry season plot in site 2 there was actually more after th=
burn than before, The understory litter compartment
received no inputs for several months until herbacouss
material h-gan to die. By tho 12 mo sampling nerioi some of
the hardwoods had also shed some leaves. At 1 yr some ')
the oldest palm fronds were becoming senescent, buit were not
dead and therefore not 7et part of the unnerstory li'tor.
There was some decrease in understory litter nass diiin
the first two months after burning in all plots (Annen-li
3) From 2-7 mD after burning the dry season brn lots
showed continued loss of mass (because these were wet season
months), while the wet season plots did not (h=cduse it was
dry). "rom 7-12 mo there was an incrpas3 in Pass excent at
the site 2 Iry season plot where decomposition out'acpe
meager litter production by shrubs and herbs. At si*e 1
much of the input to understory litter is attributable to
kt the ead of the first year the standing crops of
understory litter mass were not different from anmonts
present immediately after the burns, except for the si'e ?
dry season plot. however, the standing crops w-r0 h-low
their preburn levels except a the site 2 wet season plot
where there eas a large amount o" unconsumed v=gotation ani
rapid recovery of litter-producing hardwoods.
The standing crops of nutrients in the nnd-rstorv litter
shovel various patterns during the postburn year. Larqe
fecreasss often occurred luring the first posthurn rainy
period, 0-2 no following wet season burns and 2-7 ml after
dry season barns. Potassium in particular showed leachinq
losses of >80-90t of the amount in the postburn litter. Fr
most of the nutrients there was some net increase d rini the
7-12 mo periLd. Phosphorus, however, showed initial losses
and no significant change during the last S no period.
"itrogen and Ca showed the least net loss during th- voer
and were not different from the amounts present immediat=lv
after the burns (except for the site 2 dry season plot which :
lost mass throughout the period).
In contrast to the understory litter compartment, which
had no innuts during the firs several months 1cter birninr,
the pin. litter rcecived continual inputs. ?n.c nertle?
fall throughout the year, but at highest rates during th?
wet season (Pig. 17). Short term peaks in neertlfall ar?
caused by high winds. The annual needlefall was about 320
g/mn for site 1 and 260 g/m2 for sit- 2 (Table 9).
Seedlefall constitutes 75-80 of total pins litterfall.
Pine branches, mostly <3 cm diameter, contribute about a
tenth of tha litterfall mass, and seed cones and
miscellaneous materials make up about the same fraction.
Some vear-to-year variation in litterfall is to he Ypex'ect-
needlefall during the study period was about vveraqg a-
I I I
AS J I F M IM I J I J I I I I S I I J I
A S O N D'J FM A M J J A S 0 N D'J FM
Figure 17. Pine needlefall in the study plots and an
unburned area of site 2. Closed triangles show time of burn
and open triangles the 1 yr anniversary of the burn. Absence
of bars means that no sampling was done.
I I I I I I I I 'a I I I I
r-H m -lm rl r0 nl rm
A in Z3 mn r' -I CV IT
.T d C r OtoOD -1 C a) 0 -4 m
iLHC- yH(N (NH I.-1 N m LA 0
H- -1 -4 -4 r-4 r-q I H -4 H -4
r-4N N o- 0
SO r 7 Ho! NH
O( NH mr(Ln mm (NmN
O r, D 00 o 0
vnW o (NL .N M mmm oor No
a m i m N c m c
SCN N c mm
- W r r- -i
0 r oN- N
rH -4H H H-
* il r-
(N l (VN
+1 +1 +1 +1
0 00 0 qr
a; 1 r
CN Lo all C) Ln Ch m fi ^> msCN M
[r- (r'- in) OO O()a%-4 m oL r-
N 0 0 0 m 0
r-4 -o o
T (N o
* ooo o
+1 +1 +1 +1
oC) ) o-
C $ C r r.
0 0 0 0
Un E Hi a) H U) ) U) 0
r-H *- H *O U (n 4-H H *O- -I U L 4) 4-)
0'0a u 0 a'o r C0 c o ()a 0c0 u 00
0 ) U) E-p 0 ) U) M Z E O Q) UJ O- ww 0 z E-4 (a CE-a
U) w)-4 ( i H 0 U) ) *. a) -. p o o)-1
m (Z Z0U M UZ XE-1 mZxqU a)za
) 0 0
0 o T3 3
S(N (N (N
) a) a) ) a
u 0E m
LA LA LALA
other locations in Long Pine Key (A. Herndon, unpublished
data). The number of seed cones was probably higher than
average, at least for site 1, because there was a better
than average seed crop in the autumn of 1939. The
deposition of nutrients through pine litterfall ranged from
about 2 g/m2 of Ca and 1 g/mr of N to 0.03-0.05 q/m2 of ?
(Table 9). Ine notable aspect of the nutrient inrnts is tF'
high concentration of K and the low concentration of Ca in
pin czones relative to other litter tvpes.
Pine liter mikes up the maior portion of the f'il mags.
The material remaining after a Fir? is mostly heavier pieces
such as branches and cones, unless the fuel is moist (;,4.
site 2 wet season burn). Pine litter mass showed a more or
less continuous increase ercent for the 9-2 mo oerio,
following tih wet season burns where moist con1;tios anI
the nutrizent release in the ash may have 3timula*
lecomposition. By 1 yr all plots were still- far below
preburn levels: site 1 about 50* and site 2 33-40' -o
The nutrient standing crops in pine litter showed' a
pattern very similar to mass with some decrease 0-2 mo
following wet season burns and increases otherwise. The
percent recovery at 1 vr was similar to mass for all
nutrients except N, which only reached about 337 at site 1
3nd 20% at site 2.
The recovery of total litter mass followed a pattern
dominated by the pine litter except for the ldcline between
7 and 12 no it t1s site 2 dry season burn plot causs by! a
drop in understory litter. At one year litter mass was
42-62% of its praburn level. Phosphorus and Ca recovered in
proportion t3 dry mass. Nitrogen was much lower 1han dry
mass (26-37A) because C:N ratios decrease with
decomposition. Potassium recovery was high relative to
mass, esenaiilly at site 2, because of the high proportion
of relatively unweathered litter materials.
TPMact of wires on Pines
There is some indication of a slight increase in the rate
of needlafall immediately following the burns (Oiq. 17),
even though there was little scorching of neseles. The
stress of hijh taeperatnres may lead to senescence of nrePl0
fascicles earlier than normal.
In both site 1 plots there was no mortality of pip? trees
during the year after burning (Fiq. 5). In contrast, a'
site 2, where the trees were smaller, some trees died (vigs.
6 and 7). In the wet season plot at site 2 six trees were
dead 1 yr ifter the burn and in the dry season plot 98 +*res
were dead, including virtually all trees < 7 cm dbh., one
of these treas showed substantial scorching ind n 1al npe"r
to be healthy for the first few months after the fires.
There was evidence of bark beetle activity in all the 9e
trees, but there is no way of knowing whether the insects
were responsible for the deaths of the trees or whether they
only attack] trees that were already dying. T' is cl-ar,
however, that high temperatures around the stcms of Sout'h
Florida slash pine trees can lead to their deaths. Three
years after the dry season burn at site 2 most of the pines
had cracks erudinj resin in the bark of the basal 1-? m of
Under the burning conditions of the eTperimental burns
all Dine seedlings were killed by the fires (Table 105). ms
season of burning has a pronounced effect on +-h
establishment of new seedlings. Seedfall is from S-teimber
into Novembrc; therefore burns that occur in the wet season
before seeffall create excellent conditions for see?
gernination inl seedling establishment. Burns that occrr in
the dry season (after seedfall) destroy the caorrc* ve-r's
seed crop ani by the n-xt period of seedfall conditions ar=
less favorable for seedling establishment. The 198n se53
crop in Long Pine Key was relatively good and the wet season
birn plots hid much higher seedling densities 1 yr later
than dii plots burned in the dry season (Table 10).
a i i
tU 1C! -0
D 0 -H
0 w 0)
4) >4 4-) >4
Ct M (
g Q S Q
o 0 0
Soil analyses show some striking differences in th-
properties Eo the substrate between the two sites (Tabl?
11). Th'se differences are largely due to +he oresence of
pockets of tie reddish-brown "Redlani" soil at site 1. The
wet season CLot had 8.21 (S.E.=1.62) of the surface covered
by mineral sails and the Iry season plot B.uT S.7.=1.42).
A very few packets of the Pedland soil were present in the
site 2 dry season plot and none were seen in the site 2 we1
The organic matter content of the soils was much h.'br
at site 2 (iaout 46-) than site 1 (about 183), although bot-
sites are relatively high for upland soils. The higher
organic content nay account for the slightly lower nrnhurn
op at site 2. ?reburn extractable K an( M'I to not show ich
difference between sites, although K ray he so3ew'- hi T'-r
at site 2. Phosphorus is much higher at site 2 than sit? 1,
suggesting a relationship with organic matter.
Burn eff-;ts on soil properties remaining 1 yr postbnrn
include an increase in pR. This was most pronounce! in *he
site 2 samples ani in the paired Redland soil samples taken
in site 1, were initial p" was lower. Soil organic master
was unaffected by burning. There is an indication that
extractable P was reduced 1 yr after burning. The amounts
extractable by weak acid in the Pedland soil samples were
below detection limits both in burned and unburned soil.
9 in in o .
m I in --4 r- -4 L)
4- +1 +I +I +1 +1 +1 +1 +1
O 0 H m 0 -i
,- D -0 I 0 0)
Q L Hl H H N C4N H
NC C' 00 C 0N 0 rH to O
4 a m m r-
4-) en m to 0 N 0
.> n) Q .34 (N H HA H H 3cH
0 M +1 +1 + +1 +1 +1 4 +1
O m r- r' N o m m
,.C ) 5- .. ..
t C H LA O A O O to L A
3HO -0 en L m a n N en
,'- 00 L.r) o 'o r-.
S-i I I I n a in n
0 0 ..
*H (N N rH
o En .0
a) a) a
w CN r, m0 H
40 W- U
Qo-,-i Wr 44 o - m U O o "
"-I +i +i +i +i +i +i +1 +1 +i
HI'n CJ4 ( N ND O in o N -t
0 )O .
,- .,- H ) H 0 en en en o 0 r-,
H ) .4,+ + +5 +3 +O + L + +a
r--I co co 0 1 O O ) O-
O -3't O o4 o ( ,o 3d L '.0 on o ,
n D -I + +i +i +i +i + +i + +i
C M) 00
H 43 4 N ON N A N ON O
-1 ) 4(
(a ON In N ON Loo LA
mo p r* :: 0
U 1 4
H41 |l4J m' C C C
rn : cc
WU)UH 0 C 4g ) C >1U C) C) >cU) eH >1[n
(a0 m o4 p4 H 04 04 oioR w Hp4
E5-4 0 0 C
3 ec4 4c Ct>
U'o 00 4-i >j >1 4.1 >1 >1 .3 >,
CG4J-m1 H C) 1 1 C) C- 14 C 3.
H C) ]
Extractable Ig May be somewhat higher after burning, at
least at sit? 1. Burning increased extractable K in both
types of soil simples at site 1 but the increase was
statistically significant only for the Rodland soil. At
sits 2 th=re was a .dcrease in K after hurning. This may
result from aore rapid uptake by the vegetation at site 2.
Pire-caused Losses of Nutrients
One of the most obvious effects of fire is the removal of
organic matter. Nutrients are also lost by volatilization
or articulate emissions. Numerous studies have at+emnote
to ai-sure tiass losses in several kinds of ecosystems. 'n
prescribed b.ining situations it is possible to sasnl"
standing croos before and after the fire, as was done in
this study. Wit1 wildfires the approach has usually been to
compare starling crops in the burned area vi-h nearby
unburned analoqs (e.g. 3rier 19751. Spatial hferogenoi'
of fuels inl the collecti~q of nostburn ash co3se Frble's
for field studies (Prison 1980). "or example, in a lic
prescribed birn in southeastern coastal plain oine forest,
Binstock (1979) and Nguyen (19781 measured higher Tean
values of mass and nutrients after the burn than before. In
a study of fire in heather ecosystems in nqglan! Svans and
Allon (1971) gave up on field measurements and performoi
artificial barns in the laboratory. This reoresents th~
other common approach to measuring losses during fires.
Simulated burning has been done both as open ignition or in
a muffle furnace. The additional accuracy in measuring'
losses, however, is at the expense of the realism of the
Table 12 presents the average mass halanc? for th foie
burns in this study along with data crom several other
southeastern pinelands and a few other ecosystems. Th-
table does not include examples of slash burning (e.g.
Harwood and Jackson 1975, Evel Pt al. 1991). Comparisons
must be tBmnerei with a degree of caution because
methodologies anI conventions differ somewhat amoag thb
studies. Ti sone cases the fuel rPnrZsents only the fore: t
floor (litt=r) and in others litter 'rd veq-mttion. T '
studies h7 3ough (1991), Kadama and Van Lear (1o ?inh'=r
et al. (1932), Debano and Conrad (1978), and grier (1971
involved field simpling of ash, Debano and Conra vacu e--'
the litter and ash in their stuiv of chaonrral. 'o'lu-
picked uo the ash "by hand" and stated that som? ash was not
collected. The study by rough (1981) '1als with the
situation most similar to the "iami Fock Pidqg oinelanos.
The overstory was mixed stands of slash and lonqleif oines
with relatiTvly Iense understories dominated by Sersnoa
rsgons (saw nalomtto) and lex glabral (gallherryv.
The fuel consumption in the Long Pinea ey burns was
within the ringe of the other pineland burns [Table 121,
The lower consuaptiDn (both absolute and percanta e) i ;
three of tae other southeastern oineland burns is idue o
hiqh moisture content of the lower layers of the for-qt
OC NNNNNNN N
Cr J (U
C 4- 01
o) W -
o N NNo N o N N N N
- N 1 N
- 0 0 -
O 0 4
0 N 4.)
-o o w w o c -0
o0 0 m w o
0Cl-l N N T -N N
OWN N No -- Na .4 -IN
0)' 0- 0< *4-'^ ON 0) OOV c 41)
c o~ 3O O -r c' L
00)0 0 LI1)wI0 0)0)0) 00)
0 a. o -
N0)1) S- B 1Uat^-N [dN-.- 44Q..
dLI-.0N''.4 440)NN E 0) 1l~ )4" ONN c
q W W V V^ -4 Q 04
* -I 3ONN44O.ic c.4 a 4
0 4 N 4- N 0N .0 044
N N N N N
+ I- + 0) +
-~ -~ 3 .4 .4 .4
I 1 0 1
tf r~ ^-
I I I 0
4 -, ,-
-4 .1 145
m-C 0 m C -3
m 4 0 14
INOC C M C
10 4, 0 C M 4
-o .4 . (0 W C IN.
441.1 .CINC.. INC. *.40.C
40 0 04 CC C14
C. 44- 14 r *
iq ffl ^ C a\ V-
CCrCNC4 j C 144,N4.4V4.4NUC4,N
443 34 1 n C I 4 6 O
44 4,14-4, V^ Vt 0-04-
4- --4 C 44 n 0 >4 14 44 4 4, l 4 4 4,
1 0 4, u0 -4 C i 14 4114> .-4 o44 1444
-^ -it 4-n IN 4, U 4, .4 c) c4 J o C. n
.0- fl~i4 j l fl C, if O 44'- 4444 Cl
*a'-xi--^- E- H)^(O-TIC-
>.4S -4 >5 3 IN3 IN U U
o o o e
r- n n o i
0 0 N IN
c o ao r w c
(nm V (N *0-
0 'f < *^ CO N
0 00 0 00
C fl K
3 4 -4
P N .o'
0 0 0
floor (Sweenav and Biswell 19F1). Wildfires under oxtrerm
conditions 3in oF course Lead to very large losses (Grior
1975) rasslani fuels (Lloyd 1971, ChristPns-n 1977) also
have high percentage consumption rats.
The losses of 5 seem, for all oractical purposes, to bn
proportional to losses of total mass. Hough (1901)
developed i cegression equation to describe the loss of in
N (k~ /ha) = -10.55 + 0.0071 ()
where X is the loss of mass in kg/ha. The ePan I
concentration in the fuel of these stands is aboit 0.7='
(Hough 1992). La a field study not included in Table 12,
Klemmedson at al. (1963) found losses of 30T of mass and 11'
of N after prnscribed burning of ponderosa pine litter. T-
a lab stidy Kni;ht (1966) burned conifer fores- floor
samples in a muffle furnace and found losses of 1Q0 nd 2"?
for mass in! N, respectively, at 300oC and 53 and 61' It
6000C. Tn Lab studies on southeastern oine litter in whiSh
feel samples were simply ignited, Denell and Ralston (197n)
recorded losses of 71% of the mass and 58q of N whi Le',;is
(1975) founi losses of 39 and 56% for mass and N,
respectively. Tr these relatively cool burns most of the '
was lost as linitrogan gas.
Pires may also result in losses o' the so-called ish
elements (Cliyton 1976, Table 12). Rowever, undar nost
circumstances it is not possible to show statistically
significant Losses by preburn and postburn sampling (e.q,
this study and Pichter et al. 1982). The magnitude of these
losses as ocrsentei in much of the literature is lik lv Io
be overestimated. In field studies it is difficult to
sample the ash. When small plots ire burned, and psecia!l?
if samples oF fuel are burned in laboratory settings, thcre
is no opportunity for the particulate matter to settle b-ck
down on the sampled area. Significant amounts of nutrients
in articulate matter are carried away from small ",urns
(Smith and PBwes 1974, Wvans and All-n 1971). Tn nore
extensive burns much of the particulate fraction of smoko
will rttura lirzetlv to the ground. Some of the narticuilate
emissions are deoosited on the canopy ani are returned to
the forest floor by the first rain after the bolrn. Ther is
also a tendency to consider any loss reported in the
literature as rail while gains after burning are iqgored
(e.g. Boerner 1982). For example, the increase of 25! in
the amount of Mg reported by Debans and Conral (1978, Table
12) makes the loss of 16t of K seem of questionable
The ash element most likely to be lost by volatilization
is K, which is volatilized at temperatures above? 500oc. In
what ar3 pr:Sably the two hottest fires listed in Tabl! 1?
(chaparral and the Entiat wildfire) the percietaae of K 0lot
was higher than that of any other ash element. This wae
also true of the lab simulations on heather.
The ash lepositel on the soil surface is subject to
erosion losses om sloped terrain, but not in Soutnh Florila.
Much of the mineral contest of the ash is easily leach-d
into the soil by rainfall (Allen 196i, Lewis 197U,
:hristensen 1977). Recently burned ecosystems may
experience losses to groundwater, however thsse losses s=em
to be very small for coastal plain pinelenls (Boerner an-
Forman 1982, Rizhter et al. 1982). In Long Pine Key th=
high soil organize matter content should giva the soil a hiTh
catioa xcha~7e a paaity and P should be qui'klv immobhli.-~
by the abuindint :a. The rapid recovery o' +t1 vegetation
also acts as a sink for the nutrients released by th" fi-r
Althon)h the losses of nutrients (other than N) in the
borns in this study were not statistically significant it is
certain that som? losses did occur. "ow=v-r, evsn if 'n
assumes a loss of 10' of the standing crop oa the ash
elements, tiase losses could be replaced by precipitation
inputs over the period of a burning rotation, 3.'-6 7r.
Annual deposition of N, P, K, Ca, and Eg in bulk
precipitation in northcentral Florida is about 1-1.4, 0.1,
0,3-0.6, 1-1.5, and 0.2 g/ma respectively ('pndry and
Brezonik 199), Riekerk et al. 1979). Depending ipon the
estimate of input by precipitation, this may or may not
replace the substantial loss of V because losses ranqed from
1.4-2.2 g*ma-*yr-i when averaged over the time since= th-
It is to be expected that nutrient losses should more or
less cqual irnuts in ecosystems that have a long history on
frequent burning. In fact, fire may be a mechanism by which
nutrient-poor ecosystems prevent the accumulation of
Several agents of biological N-fiiation could aid in
recovery of N lost through burning. Although several
herhaceous laiumns are common (e.g. Cassia spp., Crotalaria
umrill) they are not likelv to fix significant amoilnts
(Pundal 1981). Lvsiloma latisil:l!_ is a legaiino_,s tre-,
but it is not zomaoa enough in pinelands to aid mich
nitrogen. Zimi E 1umila has a blue-green algal endophvt?
that fixes (Lindblad 1984). Eyrica cprifera, an
actinomycete-nodulated shrab, has substantial biomass in
much of Lonj Pine Key (inclulinq site 2) and may fir
appreciable i~ounits of 4. Tn a northern 1lorila slash -);in=
plantation Permar and Fisher (1993) estimated that "
cerifera witi a crown cover of 8" fixed 1.1 a nT*c-2*yr-1.
Nonsymbiotic N fixation by soil microorganisms in forest
ecosystems his often proved to be a rather minor source o' '
relative to arszipitation inputs (rjepkema 1979), Jorgens'n
and Wells (1971) found indications of increase soil
iaetylene relation activity in burned loblollv pine lots
compared to inburned controls. A later stufy by Jor"ensen
(1975) -ii lot support this finding and found 4-fixation
rates of < 0.1 g*m-z*yr-i. Vance at al. (1983) found even
lo er rites (0.01 g*m-2*yr-i) and no effect of long-ter-
prescribed burning in oak-hickory forest. In a orairi?
site, DuBois and Kapustka (1983) measured 0.8 qm-2*vr-1 f
nonsymbioti= T-fixation, about half of which was du- t3
cyanobacterii. Blue-green algae are not found in acid
coastal plaia soils (Jurgensen and Davey 1968) but theyv r?
coamon in ciccumneatral soils (;ranhall and Henriksson l119)
and abound 3i the oolitic limestone of the "iani Rock idgi-.
I ran an acetylene reduction assay on a few samples of rok
front the stuly area and fo:nd measurable rates afteT hr
If incubation. Crude =alculations indicated rates on t+e
order of 0.1 g*m-2*yr-1. It would seem that fixation bv
various taxi plus precipitation inputs over a burning
rotation could easily account for th- losses of N r-corr~l
for the experimental fires.
In the !imi Rock Ridge pinelands virtually all recovrv
of understorv species is by vegetativP means rather than hv
seedling reproduction. This is fairly common in ecosystem~
that exnpric= z high fire frequnncies. Abrahanson (193aa)
found very little change in species composition after fire'
in several pLn?-1ominated plant coamunities in southcuntral
"lorida. Bo2rne' (1981) also note relatively little chaenr
in speci-s c=apo3ition in burned areas of the vew Jorse-
This is La contrast to situations, often whsre fires are
of lower frequency but higher intensity, in whi-h there i a
distinctive )ostburn flora. The large number of herbaceoii
annuals that appear after chaparral fires is a Iramatic
example (Christensen and Iuller 1975). The degree to which
species changes result from burning depends in part on the
severity of the fire. In jack pine communities, fires
during the Iry summer months consume the upnse organic
layers of tie soil, whereas fires during the moister snrimn
do not. Sia3e species with shallow regenerativ- organs ~a
eliminated by ground fires, numerous postfire disturbanr.c
species like Fpilobinm (firewesd) become established after
summer fires (Ohmann and Grigal 1981).
Even though recovery in the rock ridq3 pin-lands is
vegetative, there are differences among the different growth
forms in the rat3 of recovery. Herbs and palms renrow v=rv
quickly, reaching their preburn dry masses within 1 yr. Tho
monocots (jcaminaid herbs and palms) and ferns havy
protected maristems that are seldom damaaed by Fires.
grasses are sell known for their rapid regrowth after top
removal (Iiltan and Lewis 1962, Daubenmire 1968). The
recovery of licots (whose buds are usually killed) rcuirrs
the activation of previously inactive maristems or the
production 3f aiventitious buds, whether thny bp on
rhizomes, roats, or the base of stems; woody dicots take
longer than iarbaieous dicots to show regrowth. eowver, a
study by Hounh (1965) in =eorgia found that Serenoa repnen
only reached 55- of its preburn mass 1 yr after burning
whereas 11 x labra, a hardwood, returned to 70q of its
preburn leveL. This is somewhat anomalous because the
preburn vegetation had bean unburned for 15 vr and there
should have been considerable stem biomass. S. reoons was
found to have greater cover 1 yr after a burn 'thn heforp
the born in i study by Abrahamson (198qb). This agrees more
closely with my findings in the rock ridge Dinelands.
Iv 1 yr IEtae the experimental burns, 130-190 7/m? of
regrowth vegetation appeared in the burned plots. This is a
fairly large amount in relation to some other postf-irn
recoveries. One year after a prescribed burn in the nw
Jersey Pine Sirrens the regrowth of herbs, shrubs, and oak
sprouts was 113 1/a1 (Boeraer 1991). In jack pin- stands
baraed by wilifires-in Mianesota the vegetation recovery
ranged from 21-131 g/a2 after one complete growing season
(Ohmann and 3rigal 1981).
The raeovrcy of photosynthetic capacity is ev=n more
rapid than the recovery of biomass because hardwoods orolnce
leaves more rapillv than support tissues. In the four burns
in Long Pine Key the recovery of ohotosynthetic tiss' s (sum
of herbs, palms, and hardwood leaves) was 59-937 of th2
prohurn amount at the end of 1 yr. Th, first ve:r recovery
of hardwood leaves alone ranged from 32-68" of the initial
quantities. The rapid recovery of photosynthetic surface is