NATIONAL PARK SERVICE 

SFNRC TECHNICAL REPORT 97-001 

Vegetation of Shark Slough, 

Everglades National Park 

SFNRC: EVERGLADES NATIONAL PARE\., 40001 STATE ROAD 9336, HOivlESTEAD FL~ 33035~6733 
VEGETATION OF SHARK SLOUGH, 

EVERGLADES NATIONAL PARK 

SFNRC Technical 

Report 97-001 

Ingrid Olmsted1 and -rhomas V. Armentano2 

1 Centro de Investigacion Cientifica de Yucatan 

Merida, Mexico 

2South Florida Natural Resources Center 

Everglades National Park 

Homestead, Florida 

April 1997 
1 

Olmsted, Ingrid C. and Thomas V. Armentano. 1997. 

Vegetation of Shark Slough, Everglades National Park, 

South Florida Natural Resources Center Report 97-ool. 41 pp. 

TABLE OF CONTENTS 

INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1 

BACKGROUND. . . . . . . . . . . . • . . . . . . . . . . • . . . • . . . . . . . • . . . . . . . . . . .. 2 

METHODS ................................................•........... 3 

Vegetation Map ................................................... 3 

Vegetation Sampling ............................................... 5 

Elevation Surveys and Soils Measurements ............................. 5 

Hydroperiod Calculations .... . ...................................... 7 

RESULTS ............................................................. 7 

Overview of Elevations, Hydroperiods and Soils ......•...........•..... 7 

General Vegetation Patterns ....................................•.... 12 

Marsh Communities ...........•.............•...........•......... 16 

Sparse sawgrass ...............•.................•.....•.... 17 

Tall sawgrass .............................................. 19 

Tall sawgrass with trees ...................................... 21 

Typha islands ........... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 21 

Spikerush marsh ............................................ 22 

Maidencane-spikerush marsh ..... . ............................ 23 

Spikerush-sawgrass mosaic ................................... 24 

Northwest Shark Slough Marshes .......•.......................•.... 25 

Tree Island Vegetation ............................................. 25 

Tropical hardwood hammock ................................. 26 

Bayheads ................................................. 27 

Bayhead swamp forest ........ ; .............................. 28 

Willow heads .............................................. 28 

DISCUSSION ........................... . ............................. 29 

Comparison with Davis's map ......................•.....•.......... 30 

Evidence for Disturbance Effects on Vegetation ..............•.......... 31 

Effects of Fire on saw grass ......................................... 31 

CONCLUSIONS ....................................................... 32 

ACKNOWLEDGEMENTS ............................................... 33 

LITERATURE CITED .................................................. 34 

Appendix I. Soils from sampling sites along the middle transect.. . . . . . . . . . . . . . . . .. .37 

Appendix II Species .................................................... 38 

VEGETATION MAP (Fig. 1) ........•.............................. Back Cover 
INTRODUCTION 

Shark Slough drainage, the largest in Everglades National Park (ENP), forms the 

southern portion of the greater Everglades system which, prior to agricultural development, 

began just below Lake Okeechobee and extended to the Gulf of Mexico. This low-lying, 

wide "river" comprises a mosaic of marsh communities, tree islands, ponds, and sloughs. In 

addition, Shark Slough supports important populations of freshwater fishes, reptiles, and 

birds, and influences the estuarine system of the Gulf of Mexico. 

Before artificial drainage of the Everglades, which began in the late 19th century, 

water depths, and periods of inundation (hydroperiods) in southern Shark Slough averaged 

greater than at present. In addition, the timing and distribution of water flows was directly 

linked to the natural hydrological cycle and surface waters moved entirely as sheet flow 

down the Slough (Craighead 1971, Fennema et al. 1994). Although historically the Slough 

was fed by direct rainfall and by surface water flows from Lake Okeechobee, surface waters 

now originate entirely from diked impoundments immediately to the north of ENP. In 

addition, water flow within Shark Slough is diverted away from its channel by L-67 

extension, a levee which extends about 16 km south from Tamiami Trail, nearly bisecting 

the Slough. 

The imposition of artificial controls upon the natural system has led to important 

changes in the hydrological regime of Shark Slough. Comparison of water levels from 

gauging stations to computer simulations of surface water flows in the absence of the 

present system of roads and water control structures shows that the altered system has lost 

much of its dry season flows. Furthermore, the Slough has experienced larger peak wet 

season flows than would have occurred under natural conditions (Fennema et al.1994). 

Water management practices over the past several decades also have diverted large water 

volumes to the west side of Shark Slough, significantly reducing the proportion of the flows 

passing through the main channel of the Slough. 

Thus, depending on their distribution within the Slough, plant communities have 

been exposed to wetter or drier conditions over the past half-century than would be expected 

in a natural rainfall-driven system. Although as discussed below, several authors have 

attempted to determine the effects of hydrological alterations on the plant communities of 

Everglades National Park, relatively little is known of the extent that the current structure 

and distribution of vegetation within ENP has departed from pre-disturbance conditions. 

As a first step in investigating vegetation patterns in Shark Slough within Everglades 

National Park, data were collected from field plots in 1980-81 under the direction of the 

senior author in o;'der to establish a quantitative base-line suitable for evaluation in plant 

community composition and structure. The base-line was needed both to increase basic 

understanding of the dynamics of Everglades vegetation and to provide the information 

essential to evaluate the effects of managed freshwater inflows upon ENP ecosystems. 

Circumstances prevented the completion of the data analysis and report-writing phases of the 

project although a vegetation map (Fig. 1) was produced. Because of the continuing need 

for an accessible base-line of data on Shark Slough vegetation, particularly given the steps 

1 
currently underway to restore the Everglades, the junior author, cooperatively with the senior 

author, has completed and updated the unfinished report. . 

Specifically, the objectives of this report are to: I) descnbe the patterns of ~Iant 

communities within the Shark Slough portion of Everglades Nallonal Park as they eXIsted 

in 1980; 2) describe quantitatively the composition of the marsh communi.ties; 3) describe 

qualitatively the composition of selected Shark Slough tree comrnuruues;. 4) provl~e 

supporting data on elevation, hydroperiods and soils for sampled areas, and 5) illfe~, wlthlll 

the limits of available data, the changes in vegetation that may have occurred III Shark 

Slough. 

BACKGROUND 

The area of Shark Slough considered in this report is restricted to the portion south 

of the Tamiami Trail, northeast of the estuarine areas, west of the Levee 67 extension, and 

east of the western Slough boundary as indicated in Figures I and 2. Ail of this area, 

estimated at 57,725 ha (Kusblan et al. 1975) lies within ENP. Northeast Shark Slough, 

located east of L-67 extension, although directly connected to the study area and authorIZed 

for addition to ENP, is not covered in this report. 

Shark Slough is a shallow, natural basin oriented along a longitudinal northeastsouthwest axis. Slough widths vary from 9-17 miles (northeast to southwest) and hydraulic 

gradients are 2-3 inches (5-7.5 cm) per mile, producing extremely small velocity vectors 

characteristic of sheet flow. Water quality, which had been monitored for about 25 years as 

of 1980 (Flora and Rosendahl 1981), had not been significantly degraded throughout most 

of the ENP portion of Shark Slough at the time that the vegetation inventories were 

conducted. 

The Slouoh differs in several aspects throughout its extent within ENP. The northern 

portion of the Sl~ugh is higher in elevation and consequently supports somewhat different 

plant communities than elsewhere in the SlouglJ, particularly in its main channel. In 

addition, although the tree islands in most of the Slough, as an apparent effect of the su:ongly 

directional flow, are distinctly elongate or teardrop-shaped, the higher hammocks III the 

northern portion lack the characteristic "tails" of the tree islands in the lower Slough. In 

contrast, the southernmost portion of the Slough intergrades into a broad transitional area that 

increasingly supports plants adapted to marine influences. In this zone, the water traversing 

the Slough gradually becomes distributed as a complex of small streams that coalesce 

within mangrove forest into the Harney, Shark and Broad Rivers. Thus in this region about 

20 km inland from the Gulf of Mexico, the Slough as it is configured further north, comes 

to an end. The area of the current study stops short of the transition zone .although even 

within the area we cover, coastal influences can be discerned in the vegetation, particularly 

within tree islands. 

The soils of the Slough are of two major types: organic muck and calcareous marl. 

The thickest organic soils (up to 1.5 m deep) occur in the centra! Slough towards the 

southern end. The higher flanks of the Slough are rockier and overlain with marl. The marl 

is intennixed on with sand on the western side. 

2 

Both Everglades peat, derived principally from tall sawgrass marshes, and 

Loxahatchee peat, derived mostly from deep water communities characterized by white 

water lily (Nymphaea odorata) are found within the Slough, the latter predominating within 

ENP (Cohen and Spackman 1984). Deposition of organic sediments in the southern 

Everglades began about 5000 years ago (Gleason et al. 1984). 

Marl deposits, formed through the precipitation of calcite crystals by periphyton, are 

usually found where mean annual hydroperiods allow for annual decline of the water table 

below the soil surface for protracted periods (Browder et at. 1994). In addition, in some 

Shark Slough areas, current hydrological conditions in the open marshes favor both marl 

formation and organic soil accumulation, resulting in a mixture of muck and marl in the 

surface layers. Fires, particularly during droughts, often have destroyed peat soils, leaving 

rock or marl surfaces (Craighead, 1971, Wade et at. 1980). While southern Shark Slough 

may be relatively free from the consequences of such interventions compared to areas to the 

north and east, the northeastern portions of the Slough probably have experienced 

alterations of peat deposits as a result of overdrainage and fire (Craighead 1971). 

l\.1ETHODS 

Vel:etatjon Map 

The vegetation map documented by this report (Fig. I) was developed in association 

with a copy of a color infrared photograph taken in January 1973 by a NASA U2 flight. 

A copy of this photograph is available for inspection at the junior author's institution. The 

vegetation map presents communities encountered along three transects established across 

Shark Slough. An enlargement of the infrared photograph (1:16600) was used in the field. 

Plant communities were identified from the photograph and verified on the ground on the 

basis of dominant species. Plant community characterization was further accomplished by 

detennining species composition and structure of the vegetation types. Field checking of 

infrared signatures and of final vegetation units on the transect maps was carried out 

extensively by helicopter and on foot. 

Several sources of error can result from shortcomings in interpretation of infrared 

photographs although the errors are believed to have been kept acceptably small through 

intensive ground-truthing and the quantitative plot sampling. The greatest risk of errors in 

map interpretation were associated with differentiating the many color variations on the 

photograph. In particular, in the open spikerush (Eleocharis cellulosa) and sawgrass 

marshes, delineation was difficult because of the variable reflection of periphyton. This 

difficulty necessitated the establishment of a "spikerush/sawgrass" vegetation unit. 

The presence or absence of small, scattered trees in the tall sawgrass stands could 

not always be verified because of their scant signature. Cattail (Typha domingensis) stands, 

typically small and diffuse, could not be seen from the infrared photograph and are only 

3 
Figure 2: Map of Shark Slough· within Everglades National Park 

showing hydrological gauges mentioned in the text. Panther ~ound lfound along the middle transect) and Johnny Buck tree 

island (found near the north transect) are olse shown. 

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indicated when they were identified on the ground. Willow heads were identified from the 

ground or when ponds were visible on the infrared photograph. On the photograph, only 

large willowheads without ponds could be identified. Many of the willowheads on the 

northern transect were verified from ground-truthing work conducted in an unrelated study 

(Kushlan, unpub. data). 

Vegetation Samplin~ 

The plant communities described represent the main types found in Shark Slough 

within ENP. Over the years, many telTIlS have been reported in the literature to represent 

the same or very similar community types. Table I compares the terminology used in this 

report with the synonyms used by other researchers, dating back to Harshberger in 1914. 

Three transescts from six to 12 km long were established in 1980 across Shark 

Slough (Fig. 1). The graminoid (sedge, grass, rush) communities in Shark Slough were 

analyzed quantitatively, using sets of five 1 m2 quadrats, arranged linearly. Five or six of 

these quadrat sets were sampled in each marsh community, yielding a sample of 2S or 30 m2

. 

Locations for the plots were selected to represent communities typical of Shark Slough as 

determined from field inspection and review of aerial photographs. Percent cover was 

visually determined for each species in each quadrat. Periphyton cover was indicated when 

encountered. Height of dominant graminoids was measured. Species composition and 

structure of bay heads, bayhead swamp forests, tropical hardwood hammocks, and 

willowheads also were qualitatively described. 

Elevation Surveys and Soils Measurements 

Relative elevation, soil type and soil depth across the Slough were determined in 

November 1980 at points along the south and middle transects, the latter just north of 

Panther Mound, a large tree island in central Shark Slough. Elevations, taken with a Dumpy 

Level, were related to water levels at staff gauges E-8 (Panther Mound) and E-17 (for the 

southern transect) on the days the survey was taken. See Figure 2 for gauge locations. The 

gauges had been surveyed to mean sea level in 1977. Elevation was determined at intervals 

ranging from 100 to 400 m. The first two kIn of the middle transect were walked to take 

readings at intervals of 100m or less. An elevation survey was not made for the north 

transect, but the soil-substrate relationships of Rose and Rosendahl (1979) were used. 

At each survey point along the two transects, water level and soil depth 

measurements were taken and the soil collected. Along all three transects, soil samples were 

taken in each plant community. Soils were identified to color and texture by the Soil 

Conservation Service (Lake Worth, Florida). Results are presented in Appendix I for sparse 

saw grass, spikerush marsh, tall saw grass and maiden-cane communities. 

To better understand the relationship of changing elevation on community type, 

transects were established at 2-5 m intervals across plant community boundaries, especially 

tree islands. Elevations were taken on foot, using either water depth or a Dumpy Level; the 

5 
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transects were between 20 and 100 m long. On these short transects water-levels • ~ fJ • s· ~. ". [q were ~ ~ ~ " "'~ ". • ~ I Q. ttl 0 3 Q. determined relative to the particular plant community rather than surveyed to absolute mean 

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~ Hydroperiod Calculations K " " Q. 

(IF 2: 3 :J. ~ :;; 0'3[ -x E In 1981, elevation and water-level measurements were taken in all communities. 0 " ~~ ~~3i 3 ~ cr o· " ". 

. 0' !! 0' • .". " Water-level correlation equations (Probst and Rosendahl 198!) relating water depth ". " ! :<: ",I~ ~ o · ~ n 0 ~ :; ~ ~ ~ ~ measurements to gauge data were used for gauges P-33 and E-4 on the northern transect, Pen '" 5} 33 and E-8 on the middle transect, and NP-204 and E-17 for the southern transect. Probst and :r n e; ~. Rosendahl (1981) found that water level data from the continuous stations in Shark Slough "" 0' """ • • en 3 ~ 3 ~ -x 0 • It ~ ~ 

~i ~i ~i " correlated very highly (1'= 0.95) with nearby staff ga

uges. Gauge locations are given in Fig. 0' 0' " 1 n " ~ ~. " .. " " 5' 2. Data were available for P-33 over the period 1953-1980, and for NP-204 from 1973 to :r '" • s· ~ 

~ ~ 1980. Since E-!7 and P-33 were far apart, the correlation coefficient was too low to be 

3 

~ accepted for the calculation 

of hydroperiods in the southern transect. Thus the available data Ii' O"g- H g ~. ~;3 3 " 3 ~ -c ~ iii H ~i ~ . f~ on the southern transect cover a shorter time period than those available for the middle and e; ~ " Q. 

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" " ~ " northern transects. Hydroperiods for the different plant communities were calculated from II • 0 

5' " ~ " " "" Q. 

<:T ~ • 

s· water levels 

at P-33 and NP-204 and elevations were measured for the plant communities. !". S-

~ " Water depths were calculated from water levels and ground elevation for years 

except for 

" "'a' "" 

" I: -Ol 

5' 198!, when water depths were measured directly. ~ • • 'O'l!!. g " ~ ~~ ~~ ~ 

0\ O'g " !£ h ~ s· '" ~ " po ~a. 

[ RESULTS 8 "- ~U ~ 1I if $~. ~ "''''. ;;:~[a~ ~~()atl ;Db' 0 a a ~ " S\ ).c ""t: ~:E ,." [~. ~< 

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.. ~ " § . § .. ~ ~ ~. a· ~. ~ s· a. ~. .. ~ Overview of Elevations, Hydroperiods and Soils < g o • 

" il 0 .. 

i H 3 • • 3 ~ :§i!'~ Within the mar

sh communities, elevation declined from about 1.5 m in the north 

3 " ~ !! ~ . transect to abo

ut 0.4 m along the south transect, a difference of 1.1 m (Table 2). The i ~ 0;. 1 '0 

O'~ eo oa .g. 

" ~ g . 

difference in elevation across the three transects was remarkably similar, about 0.26 m, '? 

17:1:0 1:0 • • ~ 

(range= 0.19-0.33) from the highest point in the tall saw grass marshes to the low point in 

~Ii' atr:rq 3~ a;3 r a ~ -n 

spikerush marsh. Such a small difference underscores the significance of subtle topographic 

11 ~t ~sc ~ sc ~ ~ . :s" o 'Jj. -~ variations in influencing plant community development. As Table 2 indicates, the elevation & [ cr~ cr~ ~ ".~ 

~ " " '" §. "" 0' R differences, though small, have hydrological consequences as seen in associated hydroperiod 

and water depths. The relative hydrological differences are maintained across the range of 

." ~3= l!?- n " • • ~ !l' 

- ;:: annual precipitation experienced in the Everglades~ In Figure 3, the elevat

ion differences in 

~~ ~ ~ g ~ J! . " :Sq, three marsh community types are 

superimposed on water level data for years with dry,wet &j ' <:ii ' 

~ '0 '0 

~ ~ ~il' !}Q~ §' ~ ~. . :Js·B ~. ,. ,. ~ and average rainfall. The extent of inundation clearly depends on elevation. '" '" Q. 0 0 

o· " " As indicated in Fig. 

3, elevation varies within each community by about 0.2-0.6 ft 

(5 to 20 cm) with the greatest range in bayheads and hammocks. 

~p ~ 1:; ~ "."." a! if~ !II 3 ~ 

~ ~ ->~x 

~ Itt ~ ~ . ~[ .~ Fig. 3 

(next page). Elevation of Shark Slough plant communities along three transects snperimposed Q ~i o . !l' • Ii' g ~1 ~i S 0 Ci 0 

~[~ on water levels during a wet 

(1969-70), average (1977-78) and dry year (1964-65). ~ [ II 3 '" ~ "" 2: • 

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Table 2. Hydrological parameters in three community types found In tbe central portion of transects. 

1'W:tll Mlddll: Sm!tb, 

Low Hlgb Low Hlgb Low Higb 

Elevation Elevation Elevation Elevation Elevation Elevation 

5.0 ft 5.3 ft 4.3 ft 4.5 ft 1.2 ft 1.6 ft 

MSL MSL MSL MSL MSL MSL 

SPIU'!!I: SilW!U:i1U Marsb, 

1977-78 Water levels (ft) 5.6-6.8 5.6-6.8 4.8-5.8 4.8-5.8 1.3-2.6 1.3-2.6 

1977-78 Water deptbs (ft) 0.6-1.8 0.3-1.5 0.5-1.5 0.3-1.3 0.1-1.4 0-1.0 

1977-78 Water depths 18-54 8.5-45 15-46 9-40 3-42 ()"31 

(em) 

Hlgbest record 1967-79 

water deptb (ft) 2.7 2.4 2.3 2.1 1.4 1.0 

water deptb (em) 82 73 57 52 42 31 

H~drQPtdQda(!lax~l~1 

1953-1980 mean 338 323 343 335 321 260 

Range 242-366 183-366 262-366 228-365 261-365 188-365 

5 .5 ft 5 .6 ft 4.6 ft 5.0 ft 1.5 ft 1.7 ft 

MSL MSL MSL MSL MSL MSL 

Tall Sawn'" 5.6-6.8 5.6-6.8 4.8-5.8 4.8-5.8 1.3 -2.6 1.3-2.6 

1977-78 Water levels (ft) 

1977-78 Water depths (ft) 0.1-1.3 ()"1.2 0.22-1.22 0·0.8 ()"1.1 0-0.9 

1977-78 Water deptbs (em) 3-39 ()"35 7-37 ()"25 0-33 0-28 

Hlgbest record 1967-79 

water deptb (ft) 2.2 2.1 1.71 1.3 1.1 0.9 

water de[ltb (em) 68 64 52 33 33 28 

HEI!IQ~rlods (davsl~l 

1953-1980 mean 304 280 328 255 323 276 

Range 136-366 106-365 208·366 ()"365 194-365 160·365 
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The 1969-70 hydrological year was wet with protracted high water and hardwood hammocks along the north and middle transect, except in the highest portions. were inundated 

for over two months. In the the dry year of 1964-65, even the lowest elevation spikerush 

communities were free of surface water for about three months, and the sawgrass areas for 

about five months. Figure 3 also illustrates that hammocks in Shark Slough are found on 

outcrops extending above surrounding marshes by 0.45 m (1.5 ft) or more and that the two 

other forest types found in Shark Slough tree islands, bayhead and bay swamp forest, are 

clearly found at lower elevations than hammocks. 

Interannual rainfall patterns. along with water management practices. have led to 

marked shifts in the annual durations of soil surface flooding. Sawgrass marshes in central 

Shark Slough were continuously inundated for periods of two or more years three times 

within the 1953 to 1980 period (Fig. 4). During dry years, however, there have been dry 

ground surfaces for three or more months. 

Fig. 4. Number of days per year from 1953 to 1980 that the soil surface in sawgrass marshes of central Shark 

SlOUgh were free of surface water. 

SAWGRASS - CENTRAL PORTION - MIDDLE TRANSECT 

DRY DAYS DURING 1953 - 1980 (PANTHER MOUND) 

100 

V> 

~ a 

~ a 

50 

0 1. II. ~ ~ 

53 5~ 55 56 57 58 59 60 61 62 63 ~ 6566 67 68 ffY 70 71 72 73 74 75 76 77 78 79 80 

YEAR 

11 
Northern transect. The 6 Ian wide northern transect was coincident with the area sampled 

by Rose and Rosendahl (1979). These workers found that soil surface elevations varied less 

than 0.3 m in the marshes, but that the bedrock was highly dissected, indicating that soil 

depths fluctuated widely. A slight elevation gradient from tall sawgrass to the open marsh 

was observed. The highly variable surface and sub-surface elevations are characteristic of 

the general Shark Slough area sampled in this study. 

Middle transect. The lowest point along the 10 Ian long middle transect was only 25 cm 

below the highest point on the west end although surface elevation rises steeply with 

increasing distance from the Slough itself (Fig. 5). Overall, Like along the northern transect, 

the relatively level soil surfaces contrasted with the dissected limestone substrate. The 

surface of the limestone substrate underlying the soils of the middle transect forms a trough 

differing by 1.2 m between the highest and the lowest point across the trough. 

The major soil type in the slough is muck, but towards the sides oithe trough, 

calcareous marl deposits increase in depth, replacing the muck (Fig. 5). Towards the east 

portion of the central slough, marl is sometimes found beneath large areas of open marsh 

despite hydroperiods apparently long enough to promote peat formation . In many surface 

samples of the middle transect, a mixture of muck and marl occurred. 

Southern transect. The transect was located just north of the estuarine zone and 

extended 12 km reflecting the greater width of the Slough here than at the level of the 

middle transect. Again, the relatively level soil surface and dissected bedrock contrast (Fig. 

6). The central portion of the southern transect was between 80 and 100 cm lower than the 

marsh near Panther Mound in the central portion of the middle transect. The lowest points 

of bedrock along the southern transect are below mean sea level.The soil patterns in the 

Slough are influenced by the location of the transects relative to the configuration of the 

Slough. Thus the soil depths in the eastern portion of the southern transect exceed those of 

the middle transect because the main channel of the Slough swings westward at the level of 

the southern transect. In addition, limestone outcrops characterize the easternmost 2 Jan of 

the middle transect, reducing soil accumulation. The easterly portion of the southern 

transect also passes across a shallow basin towards the Watson, Lane, and North River 

estuaries to the soulh. In contrast, the western side of the southern transect rises more 

towards the side of the trough and is covered more by marl. 

General Vegetation Patterns 

Shark Slough vegetation is distinctive and clearly different from any other plant 

community in North America and perhaps the world. Even though the total area of sawgrass 

marsh is large, the apparent uniformity is interrupted by hundreds of tree islands and over 

large areas masks a mosaic of marsh communities differing in dominant species and aspect. 

Although over large tracts periphyton dominates the ground (or water) surface, often 

mantling the stems and leaves of the macrophytes, its importance is not well represented in 

this report. The floating periphyton mats usually envelop and combine with well developed 

Utricularia (usually U. foliosa and U. purpurea) thalli and other hydrophytes to the extent 

Fig. 5 (next page). Elevation, soils, and bedrock surface along the middle transect of Shark Slough, from 

west (top) to east (bottom). The numbers along the top indicate the locations of transect sampling poles. 

12 

" 

" 

" 

2 

• '" 

~ 

~ ~ 

~ 0 
that the floating complex dominates the visual aspect of extensive marsh areas. 

As noted, the three mapped transects are 6, 10, and 12 Ian wide from east to west and 

about 2 km from north to south. Each transect delineates 11 community types: four tree 

communities, four grarninoid communities, two mixed-dominance grarninoid communities (spikerushlsawgrass and spikerushlmaidencane), and one tree/grarninoid mixture (tall 

sawgrasslbayhead species). 

The total area mapped amounts to 5,873 ha, almost 10 percent of the Slough as 

defIned by Kushlan et al. (1975). Appendix IT includes all species encountered including 

those found outside of transects. 

The three transects cross the same community types but the relative importance of 

each community differs with transect (Table 3). For example, tropical hardwood harrunocks 

are abundant along the northern and middle transects but hardly present on the southern 

transect. Elongate, high-bedrock bay heads are abundant on the southern portion of the 

southern transect, but more typical circular peat-based bay heads occur in the rest of the 

slough. 

Becau

se the northern transect is relatively short, it excludes sparse sawgrass marsh 

found further east and west of the central slough. The longer middle and southem transects, 

however, do incorporate signifIcant areas of sparse sawgrass. 

The ratio of sawgrass marsh to spikerush marsh varied from transect to transect. A 

large area on the west side of the southern transect was comprised of solid "sparse sawgrass 

marsh" as on the southeastern side. The distribution of sawgrass and spikerush marsh on 

the east and west side of the middle transect and along the entire northern transe

ct was more 

patchy for the two communities. The largest percentage of spikerushlmaidencane and the 

spikerushlsawgrass mosaic was encountered in the northem transect, probably because this 

Table 3. Distribution of community types along mapped transects.' 

Percent of Transect Area 

North Middle South 

% % % 

Sawgrass 39 43 52 

Spikerush 16 7 7 

Spikerush/MaJdencane 2 15 3 

Splkerush/Sawgrass 19 11 13 

Tall Sawgrass 13 15 11 

Tall Sawgrass with Trees 4 5 9 

Bayhead 2 2 3 

Bayhead Swamp Forest 3 2 

0.1 

Willowheads 

0.1 0.09 

0.2 

Tro21cal Hardwood Hammock 0.08 0.04 

*Total Slough area equals 142,479 acres (57,725ha). 

Fig. 6(next pages). A prome of soils, elevation and plant community type across the soutbern 

transect in Sbark Slougb from the west (top diagram), throngh the central and eastern segments 

(continuation page). The numbers across tbe upper borizontal line are transect pole locations, increasiug in number from west to easL Segment lengths are 4.8km, 1.9km and 4.2kru,west to east. 

14 

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1980 

HE.t..l1 SEll. 

lEVEl ( HSL) 

area had the largest body of deep water (Table 3). The percentage cover of tall saw grass and 

of tree islands was similar on all transects. 

Marsh Communities 

The sedge Cladiumjamaicense was the dominant species in the saw grass communities. 

Its biology has been described by Alexander (1971), Steward and ames (1975,1983), Davis 

(1991), Herndon et al. (1991) and others. In this report, sawgrass communities were 

classified into sparse sawgrass community with sparse cover and heights up to 2 m, and tall 

sawgrass with dense cover and heights in excess of 2 m. In many areas, the distribution of 

DISTANCf IN METtRS 

Fig. 7. Soils, relative elevation and prevalent vegetation across 32 m of Shark Slough near the middle 

transect from west (left) to east. 

16 

sawgrass density and heights suggests the possibility of defining an intermediate category as 

has been suggested by some authors but in this study, such a distinction could be made in 

only a few sites. The relative elevations associated with the three sawgrass types is generally 

consistent with Figs. 6 and 7. 

Sparse saw grass 

The sparse sawgrass community was the most extensive in the Slough. In spite of its 

apparent uniformity in aspect, the sparse sawgrass community varied greatly in percent 

cover, height, soil type, periphyton, and associated macrophyte species. Most typically, the 

sparse sawgrass community included extensive, very sparse marshes over marl with low 

cover (usually well under 50%, sometimes as low as 10%) in which the sawgrass was shorter 

than I m. Denser stands also occur on muck in the center of the Slough with 50% cover and 

heights up to 2 m. 

The extensive sparse sawgrass marshes found toward the sides of the Slough, usually 

over marl, were lowest in species diversity and plant cover. While saw grass was associated 

with Rhynchospora tracyi, on the west and east borders of the transects, this species became 

less common towards the center, where aquatic species became more abundant. Pontederia 

cordata and Peltandra virginica are common associates here. The common spilcerush, 

Eleocharis cellulosa, was the most constant associate in the saw grass marshes. Utricularia 

species were present in all but the densest marshes. The forbs, Justicia angusta, Crinum 

americanum, and Bacopa caroliniana, as well as grasses of the genera Panicum (e.g. P. 

hemitomon and P. tenerum) and Paspalidium geminatum also occurred here. 

The elevation of sparse sawgrass marshes was usually 10-15 cm higher than the adjacent 

spilcerushlmaidencane marsh and 10-15 cm lower than the sawgrass strand. In some 

instances, pure maidencane (P. hemitomum) occupied areas between spilcerush and tall 

sawgrass. The sawgrass communities found on muck has conspicuously greater cover. 

density, and height than do those found on marl. Periphyton was characteristic of nearly 

all sawgrass marshes mantling the soil and water surface and many plant stems. Only in the 

densest marsh is the algal mat absent. In the sparse sawgrass community, the average 

macrophyte plant cover ranged from 11 % on the southern transect to 16% on the middle 

transect. 

In the sparse sawgrass conununity, the average macrophyte plant cover ranged from 11 % 

on the southern transect to 16% on the middle transect. Sawgrass frequency was 100% 

throughout the community. Spikerush frequencies were high but frequencies of other 

species were low (Table 4). The sparse marshes were more extensive than intermediate 

sawgrass stands which most often skirted tall sawgrass strands and were narrow in extent. 

About 90% of the plant cover was sawgrass. Other species contributed little cover. 

Spilcerush contributed more than a trace in only a few instances, as did Rhynchospora 

traceyi, Pontederia cordata, and Bacopa caroliniana. 

The total number of species encountered in the sample plots in all transects was 17; the 

average number of species per m' was between four and six, and the number per transect 

varied from 10 to 15. Mean sawgrass height varied from 130 cm on the middle transect to 

145 cm in the northern transect with small standard deviations in both cases. 

17 
- , 

The soil depths beneath sparse sawgrass ranged from an average of 34 cm on the middle 

transect to an average of 69 cm along the southern transect (Table 5). 

Table 4. Cover and frequency of occurrence by species in sparse sawgrass corrununity. Data 

summarized by transect. .. 

M~D 911 !:::Qvj!r EI:~S;UJ~ncY (%) 

Species N M S N M 

Cladium Jamalcense 10.75±13.5 15.44±9.9 9.26±10 100 100 

E1eocharis cellulosa 2.15±.98 0.44 0.93 100 68 

Panlcum hemitomon 0.04 0.27 55 4 

P. tenerum T T 4 

PaspaIJd!um geminatum T T 20 

Rhynchospora mlcrocarpa T T 12 

R. tracyi 0.16 T 

Aeschenomene pratensis T 10 

Aster tenuifolius T 

8acopa CaIoliniana T 0.93 30 

Crinum americanwn 0.12 T 35 

Justlcla angusta T T T 10 24 

Agal!nls harpen T T 

Pluchea rosea T 

Pontederia cordata T 0.16 5 16 

Saglttarta lanclfolla T 

UtricuJaria blfiora T T 4 

Community 

Mean Plant Cover (%) 13.1 16.2 114 

Tot.al # SpeCies 10 8 15 

Mean # SpeCies 1m' 5.6 4.2 5.7 

Mean height (em) 145 130 135 

sawgrass 

Table Footnotes: T = Trace; -=absence' N = North, M = Middle. S = South 

Water depths for sawgrass communities varied over the year from north to south. 

Measurements made between December 1980 and February 1981 varied from 31 to 38 

cm. Water depths calculated for the period 1967 to 1979, varied from 82 cm above the soil 

surface during wet months to unspecified levels below surface during the dry months. Water 

levels exceeded 1 m only for short and infrequent periods. More often, the water depths in 

this community fell to within 20 and 50 cm during the wet season. The emergent portion 

of sawgrass generally rose 70-100 cm above the water surface. Between 1953 and 1980, the 

mean hydroperiod was 330 days (range 183-366) along the northern transect and 339 days 

on average (range 295-365) along the middle transect. On the southern transect, the mean 

was 290 days (range 188-365) over the period 1973 to 1980 (Table 2). Hydroperiods varied 

more towards the sides of the Slough. On the middle and southern transects, drier conditions 

occurred on the west side of the slough sooner than on the eastern portion because of the 

steeper ground-surface slope. 

Where soil was especially shallow, rock outcrops and deep solution holes on the middle 

transect produced patches of sawgrass between unvegetated areas and rock outcrops. On 

18 

S 

10 

97 

33 

3 

3 

3 

40 

3 

43 

7 

7 

3 

10 

7 

7 

the southeast portion of the southern transect, the soil was deeper, and sawgrass more 

evenly distributed. 

Tall saw grass 

In addition to the distinctively shaped tree islands, elongate strands of tall sawgrass 

form characteristic landscape features of Shark Slough. Sawgrass strands occur where there 

is very little other plant cover and in the tails of tree islands. Tall sawgrass often surrounds 

bayhead swamp forest and other tree islands. Tall sawgrass strands are conspicuous by 

virtue of their great height and density. Heights reach at least 2 m above the soil surface and 

may reach 3 m. Stands are very dense; consequently they often burn in the summer even 

in water depths reaching 50 cm. Falling between bay heads and intermediate sawgrass in 

elevation and hydroperiod, tall sawgrass communities contain species of both adjacent 

communities. Thus its species richness exceeds that of other marsh communities. 

Sawgrass frequency reached 100% within the community, far greater than any other 

species (Table 6). In contrast to the sparse sawgrass community, sawgrass cover approached 

almost 100% on all transects. Secondary species occurring in at least 10% of the quadrats 

along the three transects were spikerush, Blechnum serrulatum, Bacopa caroliniana and 

lusticia angusta. More than in any other community, tall sawgrass was most constant in 

cover, with a low standard deviation. Even in this community, spikerush was a frequent 

Table 5. Slle analysis by community. Summary for three transecls. Water and soil depths recorded in plots at 

time of vegetation sampling. 

Tall Sawgrass Sparse Sawgrass Maidencane Spikerush 

NORTH 

Average Soil Depth (em) 48 ± 12 53 ±21 41 ± 18 30±9 

Average Water Depth (em) 24 ±8 31 ± 4.6 40± 3.6 43 ± 2.8 

Average Plant Cover (%) 96-± 8.6 13 ± 13 6±2.5 6±3.6 

Average Open (%) 4 87 94 95 

Total # Species 14 10 8 11 

Average # Species/m2 6 5.6 4.5 4 

MIDDLE 

Average Soil Depth (em) 79 +50 34-± 26 60 ± 26.4 34.2-± 19 

Average Water Depth (em) 23.6-±6 33 ± 7.5 43.9 ± 6.9 42.4 ± 11.4 

Average Plant Cover (%) 96± 10 16-± 10 3.5 ± 1.8 2.3 ± .85 

Average Open (%) 4 84 96.3 97.6 

Total # Species 14 II II 12 

Average # Species/m' 5 4.2 5.5 4.6 

SOUTH 

Average Soil Depth (em) 82.7 ±44 69 ± 13 64.4.± 40.3 48.6.± 23 

Average Water Depth (em) 26.±8 38±8.3 51.5.±6 38.3±4.7 

Average Plant Cover (%) 96 ±4.5 11 ± 10 7±2.4 2±.9 

Average Open (%) 4 89 93 98 

Total # Species 13 IS 6 6 

Average # Species/In1 4 5.7 5.4 2.8 

19 
associate, but much less so than in the sparse sawgrass community. A species not found in 

any quadrats but often encountered in ecotones between tall sawgrass and edges of small 

bayheads was Polygonum hydropiperoides. 

Table 6. Plant cover and frequency of occurrence by species In the tall sawgrass 

community. Data summarized by transect. 

Mean % Cover 1m2 Fr~gJJ~n~ ('l1!l 

SEec!es N M S N M 

Cladlum jamalcense 95.16 + 8.59 94.90 + 10 96.00 100 100 

Eleocharts cellulosa 0.36 0.90 T 23 47 

Panicum hemttomon T 13 

Typha domlnguensls T 7 

Annona glabra T T 3 

Cephalanthus occidentalis T 

Myrica certfera T 3 

Persea borbania T T 3 3 

Blechnum serrulatum T T 0.16 13 17 

Bacopa carolintana 0.20 T T 30 17 

Enocaulon compressum T 

HymenocallJs palmeri T 7 

Justlcla angusta T T T 43 13 

Ipomoea sagittata T T 10 0 

Ludwlgla alata T 7 

L. mlcrocarpa T 7 

Peltandra virglnica T 0.20 T 10.0 13 

Pluchea rosea T T T 13 10.0 

Pontederla cordata T R R 7 17 

Sagittarla lancifolia T T 3 

Utricularta blflora T 13 

Community 

Mean Plant Cover (0/0) 95.7 96.0 96.2 

Total # Species 14 14 13 

Mean # Specles/m' 6 5 4 

Mean height (em) 212 225 242 

sawgrass 

T = Trace - = absence 

• N = North. M = Mlddle. S = South 

Soil depths varied between transects (Table 5), particularly going from the central portion 

along each transect of the Slough to the flanks. Since soil depths were averaged for all plots 

along one transect, regardless of position, they varied significantly. Even though in the 

20 

S 

100 

10 

3 

3 

17 

13 

:3 

17 

3 

6.7 

3 

23 

3 

t 

, 

I 

~ 

sample plots muck depth varied from 48 to 83 cm, the muck layer often exceeded I m deep 

elsewhere near Panther Mound. 

Alligators often seek tall sawgrass strands to build nests; the decreased hydroperiod 

associated with relatively high elevation and availability of nest material may contribute to 

that choice. While soil surface elevations of the tall sawgrass stands exceed those of other 

marsh communities in most of the Slough, on the west and east sides of the Slough where 

water depths are shallower, tall sawgrass grows at lower elevations than the surrounding 

spikerush or sparse saw grass. On the west side of the middle transect, tall sawgrass islands 

are located in bedrock troughs filled with muck and surrounded by marl soils supporting 

sparse sawgrass or spikerush. The marl sites often experience hydroperiods of 6 months, 

while the lower elevation tall saw grass stands often are inundated for 8 months. This 

situation is common also in Taylor Slough (Olmsted et at. 1980) where extensive marl 

communities surround a narrow channel overlain with muck or peat that supports tall 

sawgrass. 

Hydroperiods and water depths in the three main marsh community types over the 

period of record in the central portions of the three transects were shorter than for the other 

marsh community types, reflecting the relatively high elevation of the tall sawgrass (Table 

2). The southern transect, especially the western side, shows the reverse. The highest water 

depths over the period ofrecord (1967-1979) vary substantially among the three transects, 

with the greatest maximum depths along the northern transect and lowest along the southern 

transect. 

The apparent successional relationship between tall saw grass strands and bay head 

swamp forest sometimes results in their interspersion. Also, tall sawgrass is often succeeded 

by willow or by Typha when fires bum the organic soil and destroy the sawgrass rhizomes. 

Then saw grass may gradually replace these species by rhizomatous ingrowth from 

surrounding areas. 

Tall sawgrass with trees 

The southern tails of tree islands, downstream of the bayhead swamp forest, often 

comprise a mixture of sawgrass and woody species, with tall sawgrass dominant. When a 

fire bums through such a stand, the established species generally persist, the sawgrass from 

rhizomes and regrowth of burned culms, and the trees and shrubs as sprouts from stem 

bases. Specific dynamics of the tall saw grass-swamp forest relationship, however, have not 

been adequately studied. The tree species in this community type are the same as those 

found in the tall sawgrass community (Table 6), although they are more abundant here. 

Pond apple (Annona glabra) and buttonbush (Cephalanthus occidentalis) sometimes are the 

commonest woody species. 

The elevations, soil depths and hydroperiods of tall sawgrass strands, similar to that 

of bayhead swamp forest, seems to be conducive to tree establishment. The two community 

types often intermingle, usually over small areas. The trees have open crowns and often are 

interspersed among thick stands of swamp fern (Blechnum serrulatum), occasional Typha, 

and varying concentrations of the aquatic plants Peltandra virginica, Pontederia cordata, 

and Sagittaria lancifolia. These associations may represent incipient bayheads or degraded 

willowheads. 

21 
Typha islands 

This is one of the least understood unit mapped. The species present in ENP is 

regarded as T. dominguensis. It appears to be successional to sawgrass after fire in some 

places. In some areas of the southern Big Cypress National Preserve, Typha became 

established in areas where saw grass was burned out (Hofstetter and Alexander, 1979). 

Recruitment from surrounding sawgrass rhizomes occurred after several years. The status of 

Typha in Shark Slough in 1980 was not well understood. Some dying Typha had been 

observed along the northern transect. Tilmant (1975) recognized Typha marsh as a small 

component of his study site mosaic in Shark Slough. Typha was found mostly on deeper 

soils than was tall sawgrass. Invasion of saw grass marshes by scattered Typha near Rookery 

Branch in lower Shark Slough also has been observed. 

Spikerush marsh 

In Shark Slough, the spikerush marsh was the second most extensive community 

after sparse sawgrass. Generally, this community occurs at lower elevations than other marsh 

communities The dominant species is the sedge Eleoeharis eellulosa (spikerush), with a 

scattering of other grasses and sedges, particularly species of the genera Panieum and 

Rhynehospora. Aquatic plants like Peltandra virginiea, Sagittaria lancifolia, Baeopa 

earoliniana and species of Utrieularia are also found here. The substrate can be either 

muck or marl. 

With an average macrophyte cover of 2.8% (range 1.6-4.6%), this community had 

the lowest plant cover of any association analyzed (Table 7). The low cover favors the 

abundant growth of periphyton. The average number of species was low, between 2.8 and 

4.6/m2

, with a total of 12 per transect. species. Eleoeharis was the dominant species with a 

100% frequency and a cover of 1.5-3.9%, while Panieum hemitomon and Sagitta ria 

laneifolia follow with less than I % cover and variable frequencies on the transects (Table 

7). In the open marsh of saw grass and spikerush, the most common vascular plants are 

various submerged species of Utrieularia. The importance of these species ' was 

underestimated by our data, however, because cover or frequency was considered only 

if the emergent flower stalks were present. The white water lily, Nymphaea odorata, an 

indicator species of deep water sloughs (McPherson, 1973) is a scattered member of this 

community. In contrast, this water lily dominates large areas of the slough community of 

Conservation Area 3A north of Shark Slough and appears to have supplanted spikerush 

marshes in the southern portion of that water storage basin. 

Average marl and muck soil depths of the spikerush community varied from 30 cm 

to 49 cm with rather large standard deviations. Water depths in the spikerush marsh at the 

time of sampling (38-43 cm) and for previous years were the greatest of all communities as 

expected from the elevation surveys (Tables 2 and 5). The shallowest water depths in the 

spikerush marsh were found in the southern transect.The spikerush marsh community was 

found in areas with the longest hydroperiods in Shark Slough (Table 2). Mean annual 

hydroperiods for the period of record varied from 315 to 352 days. 

However, the ranges varied from 241 to 366 days in the northern transect and 143 to 365 

days in the middle transect. 

22 

Maidencane-spikerush marsh 

This community type, distinctive because of the importance of maidencane, always 

occurs adjacent to spikerush marsh. Though it differs in aspect from spikerush marsh, this 

community had only lightly higher species richness (4.5-5.5/ m\ Table 8). ' 

Table 7. Plant cover and frequency of occurrence by speCIes In sp1kerush marsh. Data summariZed 

by transect.· 

M~lJ ~Q ~Qv~[Llm1 FrequfnQl (m~ 

SpeCies N M S N M 

Eleocharis cellulosa 3.90 ± 1.55 1.88 ± .86 1.5 ± .97 100 100 

Rbychospora mlcrocarpa T 4 

R. tracy! T T T 16 44 

PanIc urn hemitomon 0.20 0.12 T 48 24 

P. tenerum T T 4 

Paspalldlum geminatum T T T 28 20 

Justicia angusta T 4 

Bacopa carolInian a T T 28 

Nymphea odorata OAO 8 

OxypoUs fIliformis T 8 

Peltandra virglnlca T 12 

Sagittarla lancifol1a 0 .12 0.28 0.13 12 48 

Utrlcularia biflora T 4 

U. purpurea T T 4 8 

U. res u pinata T 4 

U. comuta T 4 

Cornmlmily 

Mean total plant cover 4 .6± 3.6 2 .3,,± .85 1.6,,± .9 

Mean # species/m2 4.0 4 .6 2.8 

Total # species 12 11 6 

Mean plant height em 

(sp1kerush) 76 75 70 

T = Trace 

~ = absence 

• N = North, M = Middle, S = Sou th 

On infrared photographs, maidencane-spikerush stands were not as easily recognized as 

the spikerush community and therefore, the area of maidencane community could be 

somewhat underestimated. 

The cover of this unit (3.5-6.5%) was slightly higher than for spikerush. Maidencane 

and spikerush occurred in all plots. Paspalidium geminatum is more frequent in this 

community than in the spikerush marsh. Maidencane cover was highest along the middle 

and southern transect, and spikerush is dominant on the northern transect. 

23 

S 

100 

57 

7 

20 

10 

43 
--- -------------~- -

Table. 8 Plant cover and frequency of occurrence by specIes In maJdencane-splkerush community. 

Megn 91l CQl!cr t.l m' Fr!:!l!.!en~ '!!l 

SpecIes N M S N M 

Cladlum jarnaJcense 0.50 25 

Eleocharis cellulosa 3.50 + 2.3 .80 +.5 2 .00+.7 100 100 

Panicum hemltomon 2.56 + 1.8 1.47+1.17 3.40 + 1.8 100 100 

Paspalldium geminatum 0.23 T 0.28 50 15 

Rhynchospora mlcrocarpa T--3--

R. tracyl T 0.16 10 

Bacopa caroliniana T 0.15 0.28 30 35 

Crtnum amertcanum T 3 

Justlcla angusta T 5 

Nymphea odorata 0.60 5 

Peltandra vlrglnica T 3 

Saglttarla lancifolia T T 0 .28 30 45 

Utrlcularia blflora T 10 

U. purpurea T 10 

U. radJata .2 

Community 

Mean plant cover (%) 6.3 3.5 6.5 

Mean # species/m2 4.5 5.5 5.4 

Total # species 8 11 6 

Mean plant height cm 

(maJdencane) 97 94 92 

T = Trace 

- = absence 

• N = North. M = Middle. S = South 

Soil depth varied more between transects than within them. In Shark Slough, 

maiden cane communities occur on peat or muck but not on marl. The soils under 

maidencane in the sampling sites averaged 16 cm deeper than under spikerush (Table 5). 

The latter seems to be the most obvious difference observed between the two mapped 

units. In areas bordering tall sawgrass, maidencane grows densely, to the exclusion of 

other species. This pattern is not reflected in the sampling data because plots fell in areas 

of sparse maidencane growth adjacent to spikerush growth. 

Spikerush-sawgrass mosaic 

Delineation of this type is appropriate where saw grass islands occurring within 

spikerush marsh or spikerush marshes within sparse sawgrass are frequent at a scale too 

small to distinguish separate communities. The ecotones between these two communities 

are often indistinct. On the ground sawgrass appears to be invading the spikerush marsh in 

many areas that cannot be recognized from the infrared photographs. These two 

communities are successionally related through fire and other disturbance. Spikerush 

becomes established in areas where the root system of saw grass has been burned (Craighead 

24 

S 

100 

100 

58 

28 

32 

40 

28 

1971) or in areas where sawgrass has been damaged by airboats. The transition from 

saw grass to spikerush is very abrupt in areas where fires have burned. How long it takes 

without dislurbance for sawgrass to reinvade these marshes by rhizomes from the adjoining 

saw grass marsh is unknown but certainly is much slower than the establishment of 

spikerush in burned sawgrass marsh. 

Northwest Shark Slough Marshes 

The northwestern flank of Shark Slough, on either side of Shark Valley Road, is 

higher in elevation than the rest of the Slough. The soil here is shallower than elsewhere in 

the Slough and is not a true marl, but rather a transitional deposit betwecn marl and a 

poorly drained Rockdale fine sandy loam. The marsh communities here are distinct, 

partially because they have been slightly disturbed by the construction of the road. However, 

the shallower soils and higher elevations also create differing ecological conditions. Many 

of the tree islands here, for example, are principally hammocks, rather than bayheads as they 

are in most of Shark Slough tree islands. The bay heads Ihat are present sometimes are 

surrounded by cypress. Cypress forms a few solid stands and is also scattered in the marsh, 

the only place in Shark Slough where cypress communities occur. 

The marsh or prairie communities of northwest Shark Slough differ from those 

further south in hydroperiod and soil type as well as in species composition. The sparse 

sawgrass marshes are interspersed with prairie and include Rhynchospora tracyi, Oxypolis 

filifonnis, and Pluchea rosea (Table 9). Unlike elsewhere in the Slough, there was no surface 

water during sampling. Thus both in terms of forested and marsh communities, these 

northern sites bear considerable similarity to the communities of the higher elevation 

Northeast Shark Slough and Rocky Glades to the east and southeast (Olmsted et al. 1980). 

Total vascular cover for this community averaged 6%, more like a spikerush marsh 

than a sawgrass marsh. The frequency of grasses, sedges, and forbs was high in this 

community (Table 9). In saw grass and spikerush marshes further south, usually just twei 

species are frequent, and the forbs seldom reach 30% frequency. Justicia angusta was as 

often encountered here as was saw grass. Aquatic plants such as Sagittaria and Pontederia 

were absent; two terrestrial Utricularia species were present, but none of the floating ones. 

Another distinctive feature of these communities is the presence of Myrica cerifera in 

one-third of the plots. The species was absent from the three southern transects. 

Tree Island Vegetation 

Tree islands develop on slightly elevated limestone outcrops or in bedrock 

depressions within the marshes and are characteristic of Shark Slough. Four different treedominated community types are described, of which three (tropical hardwood hammock, 

willowhead. bayhead) were discussed by Davis (1943), Craighead (1971), and others. In 

the present treatment, bayheads are sub-divided into bayheads and bayhead swamp forest. 

The latter type has not been previously described before for Everglades National Park, but 

can be delineated based on species composition. The swamp forest type resembles tbe swamp 

forests of the Big Cypress National Preserve (Gunderson and Loope 1982). The community 

types are described below and the species encountered are given in Appendix IT. 

25 
Table 9. MIxed marsh. Tram Road . 

Species Mean % Cover/m1 

Cladtum JamaJcense 

Panicum tenerum 

Panlcum hemJtomon 

P. virgatum 

Eleocharts ceUuJosa 

Rhynchospora tracy! 

Myrica cerifera 

Agalints harpert 

Justicta angusta 

OxypoUs flilformJs 

Pluchea rosea 

Utricularta resupinata 

U. subuJata 

5.23 

0 .33 

0.03 

T 

0 .64 

0.30 

T 

T 

0.04 

T 

0 .07 

T 

T 

Open 93.4 

Sol1 depth (cm) - 12-± 7 

Average water depth = 0 

Average plant cover 1m' = 5.7% 

Total # species = 13 

Average # speeles/ m' = 9 

Sol1 type = marl 

Tropical hardwood hammock 

Frequency % 

87 

63 

7 

3 

87 

67 

33 

16.7 

80 

10 

20 

37 

37 

The upstream portions of the largest tree islands in Shark Slough often have small areas 

of tropical hardwood hammock. The hammocks are found on bedrock highs rising as much 

as one meter above the surrounding sawgrass marsh (Fig. 3). Consequently, during most 

years, the hammocks are free of inundation but many .if not all are flooded during wet years 

such as 1969. In most portions of Shark Slough, the vegetation immediately adjoining 

tropical hardwood hammocks on tree islands is usually bayhead swamp forest. 

Since hammocks in the Slough are seldom more than 5()() m2 in area, the number of 

species in this tropical hardwood forest is rather low compared to other hammocks in the 

pinelands or the prairies of Everglades National Park (Olmsted et aI. 1981). Because 

hammocks are the only dry places in the Slough during the rainy season, the Indians, and 

later, whites settlers, used them as camping places and cultivated crops there as well. In 

many hammocks, native trees have been cut and exotic species planted, however, all known 

use of the tree islands by man ceased by, or soon after, 1947 when ENP was established. 

Only by the presence of exotics is there any basis for concluding that the current tree 

composi tion differs from pre-disturbance conditions. Some planted species such as Key 

Lime {Citrus aurantifolia), sweet orange (c. sinensis) and guava (Psidium guajava) persist 

in some hammocks. Large trees of the exotic Brazilian pepper (Schinus terebinthifolius) 

are present on some tree islands as is the short-lived papaya (Carica papaya) .. Although the 

latter species may have been cultivated at one time it has now become naturalized and 

appears throughout upland areas of south Florida following disturbances of forest canopies. 

26 

The presence in a few Shark Slough hammocks of the native coastal species Sapilldus 

sapollaria and Ximellia americalla suggests the influence of man but this has not been 

conftrmed. The soil depth in the hammocks that were cultivated is comparatively deep (up 

to 40 cm), while soils are thinner in the northern hammocks (15 cm). 

The major tree species of Shark Slough hammocks are Bursera simaruba (gumbo limbo), 

Celtis laevigata (hackberry), Eugenia axiLLaris (white stopper), Sabal palmetto (sabal palm), 

Ficus aurea (strangler fig) and Mastichodendrollfoetidissimum (mastic). As noted earlier, 

in the southernmost reaches of Shark Slough, hammocks are poorly developed in tree islands. 

On the southwest flanks of the Slough, however, within or near Big Cypress National 

Preserve, small elevated outcrops of limestone support local patches of hammock species 

within the bayhead-dominated portions of the tree islands. Here, large trees of Lysiloma 

latisiliqua and Quercus laurifolia, species absent elsewhere in the Slough, extend well 

above the surrounding bayheads, but other species more typical of the Slough are also often 

present. 

Each of these species, except the Eugellia is capable of attaining large size and girth. The 

tallest trees in many hammocks reach heights of 10-14 m. However most if not all 

hammocks were badly damaged by Hurricane Andrew, the first hurricane capable of 

damaging Shark Slough hammocks in over thirty years. The eye of this Category 4 storm 

passed directly over Shark Slough in August 1992 (Arrnentano et al. 1995). But although 

damage to the crowns' of canopy trees was sometimes severe in the harrunocks, mortality was 

low (Jones et al. 1997). Typically, the understory of Shark Slough hammocks is sparse and 

reproduction of overstory trees is low, at least partially due to herbivory by deer. In wet 

years, deer and feral hog destruction of the understory may be severe if high waters limit 

animal movements for long periods (Jones et al. 1997). 

In the northern portion of Shark Slough, on either side of the Tram Road, where the 

highest ground in the Slough is found, the tropical hardwood hammocks are distinctive. 

Topographic bedrock highs form plateaus that rise above the surrounding marsh prairie 

vegetation by about 2 ft (0.61 m). Hydroperiods are shorter than further south in the Slough 

and bayhead swamp forest is absent. These hammocks are more diverse in species than the 

hammock portions of more southerly tree islands and do not seem to have been farmed. 

Bayheads 

Most of the hundreds of tree islands that dot Shark Slough are bayheads. 

Compositionally Slough bayheads resemble those found elsewhere in ENP and in the water 

conservation areas to the north. A mature bay head is a closed canopy forest consisting 

mainly of seven species. Five of these are temperate in distribution: red bay (Persea 

borbonia ), sweet bay (Magnolia virginialla), dahoon holly (ILex cassine), willow (Salix 

caroliniana), and wax myrtle (Myrica cerifera); cocoplum (Chrysobalanus icaco) and 

pond apple (Annona glabra) are tropical. 

In Shark Slough, bay heads are often surrounded by tall sawgrass. Because of the very 

dense canopy cover, the ground layer is very sparse and consists mostly of swamp fern 

(Blechnum sermlatwn) and leather fern (Acrostichum danaeifolium). Canopy height reaches 

an average 8-10 m. 

Bayhead soils typically are mucks. Depths vary but in four bayheads probed in the 

southern and middle areas, depths fell between 15 and 100 cm deep. In addition, several 

27 
bayheads were reconnoitered on the west and east ends of the middle transect. Since the 

bedrock is slightly higher here than in the center of the Slough, the soil depths are shallower 

as well. Soil depths varied between 5 and 25 cm on the west side and 40 cm on the east Side, 

near the E-26 gauge. The latter was on bedrock elevated above the general surroundings. 

Typically bayheads are found in a predictable position within the elevational sequence of 

Shark Slough ecosystems. Particularly in the northern and middle transect areas, the usual 

pattern consists of a gradual increase in elevation from spikerush mars~, to intermedi~te 

sawgrass, sometimes to tall sawgrass, and then to the bay heads. Addiuonal ~ommuruty 

relationships based on data from some of the same Shark Slough areas are discussed 1D 

Olmsted and Loope (1984). The pattern is somewhat different on the east side of the 

southern transect. Here elongated bayheads are found on slightly higher bedrock and unlike 

bayheads in other areas in the Slough, are not surrounded by tall sawgrass. Here also 

bay heads often are dominated by Chrysobalanus icaco, the only tree species. These are 

probably the driest bayheads in the Slough with typical hydroperiods of only 2-~ months. In 

contrast, most bayheads in the middle and northern areas of the Slough, depending on where 

they are located relative to the topography of the Slough and whether they are on bedrock 

highs or on accumulated muck, are inundated from 2 to 6 months. 

Bayhead swamp forest 

This community is very similar in species composition and physiognomy to bayheads, 

but is not confined to relatively small circular stands as are most bayheads. Instead, the 

bayhead swamp forest usually comprises the elongate downstream portion of a tree island 

that has a tropical hardwood hammock at its northern end. The areal extent of bayhead 

swamp forest on a tree island usually far exceeds that of the bay heads and hammocks. 

While the bay head "proper" has a closed canopy and is, therefore, shaded in the 

understory, the bay head swamp forest has a very open canopy. The understory has small 

islands of sawgrass or cattails (Typha) and a number of aquatic plants like Utricularia spp., 

Sagittaria lancifolia, Pontederia cordata, Vallisneria americana and Bacopa caroliniana. 

The soil is an organic muck sometimes exceeding I m in depth. The swamp forest IS always 

found in bedrock depressions and has a hydroperiod of up to 10 month/year. If there have 

been no recent disturbances, tree heights decrease from upstream to downstream. Since 

frequency of lightning fires and prescribed fires in these areas is fairly high, however, one 

often finds a banding of differently aged swamp forest communities. These also vary in 

dominance and mixture of graminoids. Pondapple (Annona glabra) and buttonbush 

(Cephalantltus occidentalis) are frequent associates of the other typical bayhead tree species 

with Annona sometimes codominant with willow and cocoplum. 

The elevation of the swamp forest varies and is sometimes the same as that of tall 

sawgrass, but is always lower than that of the hardwood hammock. Even in the absence of 

recent disturbance, the soil surface of the bay swamp forest is very uneven because of fallen 

logs, stumps, and soil accumulation around tree bases. The difference in height between the 

hammock trees and the shorter trees of the surrounding swamp forest is quite obvious and 

can be as much as 3-5 m. 

WiUowheads 

Willows (Salix caroliniana), besides being common tree island species, also often form 

28 

monotypic stands in willow heads. Many willow heads are actually ponds that are surrounded 

by willows in bands of different widths. The ponds probably had their beginning in slight 

soil depressions which were deepened by the work of alligators. Willowheads are mostly 

surrounded by tall sawgrass strands which are on equal or even slightly higher elevation. 

Tall sawgrass and willows, both typically found on muck soils, are successionally related 

communities. When fire consumes surface muck and thereby lowers the elevation in a tall 

sawgrass strand, willows often invade. The position of the ecotone between tall sawgrass 

and willow heads is relatively fluid. Willows are intolerant of shade and, therefore, mostly 

successional or maintained by fire (Robertson 1955, Craighead 1971). Aquatic species like 

Sagittaria and Pontederia are often associated with willowheads as is Leersia hexandra, the 

southern cut grass. Pontederia cordata, Sagitta ria lancifolia, and Peltandra virginica 

stands are often found near willowheads on thick mucks. 

DISCUSSION 

A question of both scientific and resource management interest concerns whether the 

present vegetation of Shark Slough represents a significant departure from the natural 

pattern of the pre-drainage period. Unfortunately, pertinent information is quite limited, 

dating back no further than the 1940s. Earlier observations, although made by knowledgeable 

scientists, were at best semi-quantitative and limited by accessibility. With a few limited 

exceptions, noted below, previous observers left no field data or sampling locations that 

could be re-analyzed. In addition, although it can be assumed that hydrology exerts an 

important influence on wetlands vegetation, detecting plant community responses at specific 

locations can be obscured by hydropattern variability (Gunderson 1989). Another 

complicating factor operating at specific sites can be intercession of fires that destroy 

existing vegetation and even soils, altering local hydrological regimes. Particularly where the 

prevalent vegetation is herbaceous, detailed sampling at fixed sites over one or more time 

intervals is essential unless changes are so great as to be unambiguously detectable by aerial 

photography or more casual assessments. 

It was not until the late 1950's, when major drainage canals in the Lake Okeechobee and 

northern Everglades region had been in place for some 30 years, that more detailed work 

appeared on the vegetation of Shark Slough, mainly north ofENP.These impounded water 

conservation areas, separated from the Park by the Tarniarni Trail and associated canals and 

levees, once comprised major components of the greater pre-disturbance Shark Slough 

system. The systematic observations of Loveless (1959) and others make it clear that radical 

alteration of natural hydrology caused profound changes in the natural vegetation of the 

water conservation areas. McPherson (1973), Goodrick (1974), and Yolk et al. (1974) 

reported further on the vegetation response to the protracted flooding in the water 

conservation areas already manifested prior to the time of the present study. 

The landscape-scale changes in the water conservation areas have been profound and 

readily detectable at even a relatively coarse level of resolution (Alexander and Crook 1975, 

Davis et al. 1994, Rutchey and Yilchek 1994). Tree islands have changed character or 

disappeared, and sawgrass and spikerush marshes have declined over large areas. A vast 

29 
-.r---------------------------------------------------------------------------------------------------

deep-water slough community of mostly aquatic plants exists today in the impounded areas, 

with Nymphea odorata as a widespread dominant. 

Comparison with Dayis's Map 

One of the few sources of earlier information on Everglades vegetation is the monograph 

and map produced by Davis (1943). The current vegetation of the water conservation areas 

represents a strong departure from the vegetation described by Davis (1943) who based his 

work on field work and on aerial photography of 1940. In contrast, departures from the 

patterns observed by Davis in Shark Slough south of Tamiami Trail are less obvious 

primarily because the changes have been less profound. Direct comparisons with Davis 

(1943) are problematic, however, because Davis's analyses were not quantified or 

documentable as to location. He assigned most or all of southern Shark Slough to the 

category "slough and tree islands areas". His map (Davis 1943) refers to the same area as 

"sloughs, ponds and lakes (with aquatic plants)", but included tree islands and sawgrass 

either as elongate extensions of the tree islands or separately as strands. The slightly higher 

east and west flanks of Shark Slough were described as southern marshes and wet prairies. 

The western and eastern ends of the middle and southern transects of the present study 

approach areas designated by Davis as southern marshes and wet prairie without actually 

extending into them. Note that Davis intended "wet prairie" to refer to marl areas dominated 

by mixtures of forb and grarninoid species but with dominance by sparse sawgrass and 

spikerush and increasing admixtures of many other species associated with slightly higher 

elevations and sometimes on rock outcrops. 

Inspection of 1940 aerial photography suggests that, at the coarse scale level of 

resolution, Shark Slough within ENP has remained essentially stable in its distribution of 

major plant communities. But the "slough" community, an indicator of long-term inundation 

by re.latively deep water, may not have covered as large an area in 1940 as indicated by 

Davis's map for Shark Slough. Aerial photography of 1940, 1954, 1965, 1971, and 1973 

reinforce the impression that deep-water slough areas covered smaller areas than suggested 

by Davis's map. Similarly, in 1980, unlike in adjacent water conservation areas, the slough 

community occupied only small areas in Shark Slough within ENP. Instead, at least some 

of the areas designated as slough on Davis's map appear to have been occupied by sawgrass 

in 1980 while spikerush and maidencane marshes occurred in the deepest areas instead of a 

slough community dominated by aquatic species. 

That water lily sloughs may have prevailed over more extensive areas in earlier times 

is suggested by the predominance of Loxahatchee peat in Shark Slough (Cohen and 

Spackman 1974). A plausible explanation for the apparent discrepancy between the 

prevalence of Loxahatchee peat, known to be formed under essentially continuous deep 

inundation, and the relative scarcity in 1980 of the Nymphaea - dominated aquatic 

communities that produce Loxahatchee peat, is that by the 1940's, uncontrolled drainage 

may have already eliminated most Nymphea communities in Shark Slough. Further 

investigation of hydrology-peat-vegetation relationships would help test the validity of this 

tentative conclusion. 

Davis's (1943) description of other grarninoid plant communities also is somewhat 

incompatible with 1980 patterns. The same species are present, but in different 

30 

combinations. Spikerush and maidencane marshes appear to resemble Davis's slough 

communities except that he does not mention the two species in discussion of the slough 

community. These discrepancies are not fully understandable and thus cannot be clearly 

attributed to real changes in vegetation. But the fact that Davis does not mention the 

currently abundant sawgrass marshes in Shark Slough, is further suggestive of a significant 

shift in vegetation that may be explainable by ac-tificial drainage. 

Eyidence for Disturbance Effects on Yej;etation 

More detailed observations also demonstrate that further vegetation change has occurred. 

Kolipinski and Higer (1969) show that community changes occurred from 1940 to 1967 in 

several areas of Shark Slough within ENP that appear consistent with the effects of 

hydroperiod reduction. They concluded that marsh once characterized by periphyton, 

spikerush, Utricularia spp., Sagittaria lancifolia, and Rhynchospora spp. had declined since 

1940. In sites near our northern transect, Kolopinski and Higer (1969) found that these 

species were replaced by sawgrass communities. In lower Shark Slough, just south of the 

southern transect, Rhizophora mangle (red mangrove), willow, cocoplum and pond apple, 

all woody species, had expanded in place of aquatic species. The woody expansion originated 

along the margins of tree islands and the banks of headwater streams which become common 

in lower Shark Slough. 

Further evidence of the expansion of woody species into herbaceous marsh during the 

era of water management can be found in several papers (e.g., Johnson, 1958, Wade et al. 

1980, and Alexander and Crook, 1975, 1984). It should be noted, however, that the spread 

of "bushy vegetation" reported by Johnson (1958) could not be confirmed by the senior 

author through inspection of aerial photographs. 

Alexander and Crook (1975,1984) described vegetation changes from the 1940s to the 

1970s of several kinds throughout south Florida based on field studies supplemented by 

literature review and interpretation of aerial photographs. They concluded that the major 

factors influencing overall south Florida vegetation (including, but extending far beyond 

Shark Slough) were water management, increased fires, sea level rise and displacement by 

exotic species. 

Davis et al (1994) provide some confmning evidence of drainage-induced vegetation 

change in Shark Slough. They examined aerial photographs from the mid-1980s that covered 

the square-mile field plots inventoried by Alexander and Crook (1975). Two of these plots 

were located in the study area being reported on here. In both cases, decrease in wet prairie 

(equivalent to Eleocharis and P. hemitomum stands in the present study) and increase in 

sawgrass marsh was noted. In plot #61 , located near the middle transect of the present study, 

shrub cover also increased. Two other plots, located near Tarniarni Trail also exhibited 

declines in wet prairie and increases in sawgrass cover. In this area, various kinds of 

disturbance have led to altered vegetation, including elevated soil phosphorous levels (Doren 

et al. 1997). Overall, our information on the relative elevations and hydroperiods of these 

community types indicate that reduced hydroperiod is a major contributory factor to the 

observed effects as Alexander and Crook (1975) and Davis et al. (1994) have suggested. 

Effects of Fire on Sawj;rass 

Fire has influenced the extent and composition of plant communities in the Slough for 

31 
a long time and continues to affect the successional relationships between sparse saw grass 

communities and Eleocharis marshes, as well as between tall sawgrass strands and woody 

vegetation. The natural fues that have occurred in south Florida have varied from light to 

catastrophic, depending on water levels and fuel loads. Fire frequency has probably 

increased during the last 50-60 years or more because of increasingly drier conditions during 

the spring (Davis 1943, Robertson 1955, Craighead 1971). Taylor and Herndon (1981) 

reported on the fire history of Everglades National Park, including lightning fires, 

prescription fues, and man-set wildfues. 

Sawgrass, a rhizomatous plant, is well adapted to fue and easily bums in dense stands, 

even over water in the summer. Under continuously high water conditions, sawgrass forms 

tussocks, a condition not often seen within the study area. But the rate at which marshes 

are subject to rising water levels is important. Fire and deep flooding appear to be critical 

co-factors explaining cases of saw grass mortality. When fire burns back culms immediately 

prior to rapid flooding which often follows storms, water levels can rise at rates sufficient 

to inhibit sawgrass regrowth which normally follows burning (Herndon et al. 1991). A 

saw grass kill of about 40 ha occurred because of flooding following a fue in Taylor Slough 

after Tropical Storm Dennis in 1981 (Herndon et al. 1991). Therefore, proper timing of 

burns is very important. 

A different type of decline of sa wgrass populations in patches has often been reported 

within Shark Slough. This condition, designated as sawgrass decadence, and reported by 

Wade et al. (1980), Alexander and Crook (1984) and others, represents local areas of dieback of sawgrass culms that sometimes are open to colonization by woody species.Causes 

are seldom obvious. Lack of fue, nutritional problems, fungal infection in meristem, and 

a boring larva (Scirpophaga perstrialis) have all been cited as possible causes (Hofstetter and 

Parsons 1975). Of interest though is the observation that extensive areas of sawgrass 

decadence that caused concern in the early 1970s could not be distinguished from healthy 

(burned or unburned) sawgrass in 1980 (Wade et al. 1980). Thus the extent to which 

episodic die-back of sawgrass related to fue and flooding interactions or to biotic factors 

contributes to shifting vegetation patterns is unclear except for spedfic areas and times. 

However, because the area of sawgrass probably has expanded in Shark Slough in the past 

half-century, episodic sawgrass die-back is unlikely to have been a primary factor in the 

changing vegetation patterns. 

CONCLUSIONS 

Shark Slough is the southern portion of the greater Everglades marshes extending from Lake 

Okeechobee to Everglades National Park. This report provides baseline information on the 

composition of the major vegetation types found in Shark River Slough within Everglades 

National Park in relationship to environmental factors. In 1980-81, eleven vegetation 

community types were identified, including five herbaceous marsh communities. Each of 

these, sparse and tall sawgrass, spikerush, and maidencane marsh, was analyzed for plant 

cover, composition, and species frequency along three cross-Slough transects. Four types of 

32 

woody communities, tropical hammock, bay head, bayhead swamp forest and willow head, 

were delineated and qualitatively described. 

Sparse sawgrass is the predominant marsh community type in Shark Slough, covering 

45% of the mapped area. Tall sawgrass covers another 13%, and spikerush-sawgrass 

mixture 14%, totalling nearly three-quarters of the Slough occupied by sawgass-dominated 

communities. The Shark Slough marsh communities are distinguished by their low species 

diversity (3 to 6 species/ m 2), single species dominance and low vascular plant cover (2-

16%) except for tall sawgrass stands where cover reaches 96%. 

On the broadest scale, the structure and extent of plant communities in Shark Slough are 

largely similar to the way they were in 1940, influenced mainly by hydrology and fue. On 

a finer scale shifts in several community types appear related to alterations of the natural 

hydrological regime. 

One plant community, the aquatic "slough type", is uncommon at the present time, less 

so than reported for 1940. At least some of the apparent reduction in slough area, however, 

seems attributable to the limited characterization of Shark Slough vegetation presented in 

the earlier work rather than to actual conversion to non-slough vegetation. But it is highly 

probable that slough vegetation was more ubiquitous 1 00 years ago, before artificial 

drainage (Johnson 1958, Kolipinski and Higer 1969, Craighead 1971, Alexander and Crook 

1975, Hofstetter and Parsons 1975). 

Many reports in the late 1960's and early 1970's and again in the 1990s mentioned the 

deterioration or decline of sawgrass in the overall Everglades and the increase of woody 

vegetation. As far as Shark Slough in Everglades National Park is concerned, reduction of 

areas dominated by sawgrass communities over the past 50 years (as of 1980) has occurred 

only locally, and it would be very difficult to say that saw grass had diminished in extent. 

Although the invasion of woody species into saw grass communities has occurred, there is 

a dynamic relationship between sawgrass and woody species that would allow for increase 

or decrease of either community, depending on fue and water level. Johnson's interpretation 

(1958) of increase of "brushy" vegetation was incorrect. However, the detailed, measured 

changein woody vegetation by Kolipinski and Higer (1969) along creekbeds was probably 

accurate. The available evidence, however, supports the conclusion that sawgrass 

communities have expanded in Shark Slough as a response to reduction in hydroperiods. 

ACKNOWLEDGEMENTS 

The logistics of field work required perseverance and good humor from Vicki Dunevitz, 

Lois Granskog and Jill Johnson. Dr. W.R. Robertson, Jr,. provided astute review of report 

drafts in 1982 and in 1996. In addition valuable comments were provided in 1996 by David 

Jones, Jim Snyder, and Mike Ross. 

33 
LITERATURE CITED 

Alexander, T. R. 1971. Sawgrass biology related to the future of the Everglades ecosystem. 

Soil Science Sm;. Smilll Florida ~ 31 :72-74. 

Alexander, T. R. and A. G. Crook. 1975. Recent and long-term vegetation change and 

patterns in south Florida: Part II: Final Report. South Florida Ecological Study. 

827 pp. 

Alexander, T.R. and A. G. Crook. 1984. Recent vegetational changes in South Florida 

pp. 199-210 in PJ. Gleason (ed.) Environments of South Florida Past and Present II. 

Miami Geological Society, Coral Gables, Florida. 

Armentano, T.V. , R.F. Doren, W. J. Platt, Jr., T. Mullins. 1995. Effects of Hurricane 

Andrew on coastal and interior forests of southern Florida: overview and synthesis. 

Journal of Coastal Research 21: 111-144. 

Browder, J. P. J. Gleason and D. R. Swift. 1994. Periphyton in the Everglades: spatial 

variation, environment correlates and ecological implications. pp. 379-444 In: S. 

Davis and J. Ogden (eds.); Everglades the Ecosystem and its Alteration. St. Lucie Press . . 

Delray Beach, Fl. 826pp. 

Cohen, A. D. and W. Spackman. 1984. The petrology of peats from the Everglades and 

coastal swamps of southern Florida. pp. 352-374. In P. J. Gleason (ed.) 

Environments of South Florida II: Present and Past. Miami Geol. Soc., Mem. 2. 

Craighead, F.C., Sr. 1971. The trees of south Florida. Univ. of Miami Press, Coral Gables, 

FL. 212 p. 

Davis, J H., Jr. 1943. The natural features of southern Florida, especially the vegetation 

and the Everglades. Fla. Gool. Surv. Bull. 25. 311 p. 

Davis, S.M., L. H. Gunderson, W. A. Park, J. R. R.ichardson and J. E. Matson. 1994. 

Landscape dimension, composition, and function in a changing Everglades 

ecosystem, pp. 419-444 In. S. Davis and J. Ogden (eds.); Everglades The 

Ecosystem and its Restoration. St. Lucie Press. Delray Beach, Fl. 826pp. 

Davis S. M. 1991 . Growth, decomposition, and nutrient retention of Cladium jaimaicense 

Crantz and Typha domingensis Pers. in the Florida Everglades. Aquatic Botany 40: 

203-224. 

Doren, R.F., T.V. Armentano, L. D. Whiteaker, R. D. Jones. 1997. Marsh vegetation 

patterns and soil phosphorous gradients in the Everglades ecosystem. Aquatic 

Botany In Press. 

Egler, F. E. 1952. Southeast saline Everglades vegetation, Florida, and its management. 

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Fennema, R., CJ. Neidrauer, R. A. Johnson, T.K. MacVicar and W.A.Perkins. 1994. 

A Computer Model to Simulate Natural Everglades Hydrology pp 249-290. In. S. 

M Davis & J. C. Ogden (eds.): Everglades The Ecosystem and Its Restoration. 

St. Lucie Press. Delray Beach, Florida. 

Flora, M. D. and P. C. Rosendahl. 1981. Specific conductance and ionic characteristics of 

the Shark R.iver Slough, Everglades National Park, Florida. National Park Service, 

34 

South Florida Research Center Report T-615. Homestead, FL. 55 p. 

Gleason, P. J., A. D. Cohen, W. Smith, H. Brooks, P. Stone, R. Goodrick, and W. 

Spackman. 1984. The environmental significance of Holocene sediments from the 

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of South Florida II: Present and Past. Miami Geol. Soc., Mem. 

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35 
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36 

AppendlX I. Soil type and texture from sampUng sites along the middle transect. 

MIDDLE TRANSECT 

Community Pole Sol11'ype Sample Depth {em) Text'..lre and Color 

5G W- l marl top 10 small organic matter component. gray-brown. 

numerous fine sheU fragments 

5G W·l marl 20 Ughl b'ownlsh geay. Ughl loamy macl 

£L W·7 macl top 10 dark gray marl. mIXed With organic matter. 

numerous fine shell fragments 

£L W· 7 macl 20 Ught. b,ownJsh geay. lJght loamy marl 

£L W- ll muck top 10 root fragments miXed. In dark brown 

5G W·25 muck top 10 <100/0 fiber (brown) 

5G W·25 muck 20 brown. bit more frtable than TS-W-2S 

TS W·25 muck top 10 very dark brown, <10% fiber 

TS W·25 muck 20 very dark brown, < 1 GOAl fiber 

5G £·43 muck with marl lop 10 very dark brown, very granular 

lntermJxed 

5G £ ·43 muck 20 brown. very BtUe fiber 

MC £-40 muck lop 10 black muck. < lOOAl fiber 

£L £·40 muck top 10 black, very granular, some marl mixed in 

EL £-40 Lauderltill muck 20 pH = 7. black 

Me £·40 muck 20 very granular. low nber, frtable. black 

£L £ ·35 mad top 10 silt loamy. gray marl with organICS. numerous fine 

shell fragments 

EL £-35 muck with marl 25 brown, very Uttle fiber 

1ntermlXed 

TS £·24 LauderhUi muck 25 blaCk, slJghtly more fibrous than E-40. soU has <10o

A;, 

flbe, 

SG £ · 6 marl with some top 10 gray, sllty marl with muck below, numerous fine 

muck s hell fragments 

SG £-6 marl and muck 15-20 sheny gray marl and muck 

SOUTHERN TRANSECT AND OTHER AREA8 

SG 5 -2 lnterm1xed muck top 10 dark brown 

and marl 

SG 5G·2 shell perrtne marl 20 grayish brown sllt. loamy marl. numerous fine shell 

fragments 

SG 5-19 muck 15 brown muck with 10% fiber content 

TS 5 ·9 muck lop 10 dark brown, fine roots mixed in 

5G 5-35 Perrtne marl. 20 Ught. broWT'Jsh gray. heavy texture, borderUne sllty, 

shallow clay loam 

SG 5·35 peat 10 shelly slit, loamy marl 

5G Tnun marl top 10 sandy loam, poorly drained, (gr1tty) transition marl to 

Road Rockdale soIl 

SGcapa.ne eawgraaa; TS=taU eawgrua; ELcEleocharis cellulosa dominatd JD.Il.Bh; Me. Panicum 

hemitomon dominated manh 

MPole" (colunm 2) refers to the nearest transect pole: a map of pole locations Is archived at the South Florida 

Natural Reso\lJ"ces Center 

37 
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PROUDLY PRlNTED ON RECY-CLED PAPER REDUCING AlvlERlCA'S DEPENDENCY ON FOREIGN OIL