U.S. Fish and Wildlife Service

Florida Salt Marsh Vole Habitat: Lower Suwannee

National Wildlife Refuge

By Ellen A. Raabe and Laura C. Gauron

Open-File Report 2005-1417

 

 

U.S. Department of the Interior

U.S. Geological Survey
ii

U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia 2005

Revised and reprinted: 2005

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Raabe, E.A., Gauron, L.C., 2005, Florida Salt Marsh Vole Habitat: Lower Suwannee National Wildlife

Refuge: St. Petersburg, FL, U.S. Geological Survey, Open-File Report 2005-1417.

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v

Contents

Abstract .................................................................................................................................................................. 1

Introduction ........................................................................................................................................................... 1

Background........................................................................................................................................................ 1

Saltgrass............................................................................................................................................................. 2

Study Area.......................................................................................................................................................... 2

Methods.................................................................................................................................................................. 5

Background........................................................................................................................................................ 5

Field surveys...................................................................................................................................................... 5

Image Processing............................................................................................................................................. 5

Results .................................................................................................................................................................... 5

Mapping ............................................................................................................................................................. 5

Field Reconnaissance ..................................................................................................................................... 6

Conclusions ......................................................................................................................................................... 10

References Cited................................................................................................................................................ 13

Photographs ........................................................................................................................................................ 15

Figures

1. Study area for Florida salt marsh vole habitat, Levy and Dixie Counties, Florida. .............................. 4

2. Potential saltgrass sites north (a) and south (b) of the Suwannee River mouth derived from

hyperspectral imagery. ........................................................................................................................................ 7

3. Known saltgrass sites north (a) and south (b) of the Suwannee River mouth.................................... 8

Tables

1. Error matrix for potential saltgrass sites derived from hyperspectral imagery. ................................... 6

2. Location (UTM 17 R WGS84) and description of known saltgrass sites. ................................................ 9
vi
1

Florida Salt Marsh Vole Habitat: Lower Suwannee

National Wildlife Refuge

By Ellen A. Raabe and Laura C. Gauron

Abstract

The rare Florida salt marsh vole (Microtus pennsylvanicus dukecampbelli) was discovered 

in spring 2004 by U.S. Fish and Wildlife Service (USFWS) personnel on the Lower Suwannee

National Wildlife Refuge. The discovery of three individuals in the southern portion of the refuge

renewed hope for effective recovery and protection of this rare animal. Further protection of the

Florida salt marsh vole will rely on distribution surveys of the animal and conservation of potential

habitat. This report details an effort by the U.S. Geological Survey to map potential habitat sites

within the refuge. The Florida salt marsh vole is known to utilize a specific type of salt marsh 

called saltgrass (Distichlis spicata) as habitat. Hyperspectral imagery acquired in 2002 for

mapping general intertidal habitats of the lower Suwannee River and estuary was re-evaluated for

this specific habitat. The results of the mapping effort and field reconnaissance identified potential

habitat in the salt marshes north and south of the Suwannee River. Saltgrass habitat was fieldidentified at flooded and elevated sites, near the shoreline and toward the marsh interior, and was

found occurring with several other marsh species, including three-square sedge, smooth cordgrass,

black needlerush, and glasswort. Image-derived saltgrass mapping was only 62% accurate.

Positive identification of saltgrass from the imagery was hindered by the variety of environmental

conditions and the co-occurrence of saltgrass with other species. Image-derived sites were mapped 

separately from field-verified locations. The tidal marsh around the Suwannee River delta itself

did not support extensive saltgrass-dominant habitat. This was due largely to freshwater flow and 

dominance of freshwater marsh species in those areas. Where saltgrass was identified as a sparse

understory, it could become the dominant cover under different conditions such as drought or

decreased river discharge.

Introduction

Background

The Florida salt marsh vole (Microtus pennsylvanicus dukecampbelli) is listed as an 

endangered species and has been known historically from only one site in coastal Levy County,

Florida (USFWS, 1997). Dominant vegetation at the original site consisted of saltgrass (Distichlis

spicata), cordgrass (Spartina alterniflora), and glassworts (Salicornia spp.). Black needlerush 

(Juncus romerianus) is also common in the surrounding area. In spring 2004, personnel from the

Lower Suwannee National Wildlife Refuge (LSNWR) collected three specimens of the Florida salt

marsh vole from a new site farther north and west from the original site (USFWS, 2004). This new

site is a remnant sand island dominated by cordgrass and black needlerush salt marsh with 
2

sufficient topography to support coastal hammock of southern red cedar, cabbage palm (Sabal

palmetto), oak, and palmetto scrub. Included in the salt marsh are patches of saltgrass, glasswort,

and high-marsh species.

The discovery of a new and separate population of Florida salt marsh vole spurred an effort

to identify additional habitat sites that may support current or future populations of the rare rodent.

Current understanding of Florida salt marsh vole habitat consists of an association with saltgrass.

This specific salt marsh vegetation was used as an indicator to map sites with habitat potential

elsewhere in the refuge.

Saltgrass

Saltgrass, also known as spike grass, is tolerant of a wide range of tidal flooding and 

salinity variations (Coultas and Lasley, 2001; Bordovsky et al., 2002; Eleuterius, 2000). Saltgrass is

a dioecious plant with 15 to 45 cm-tall, spreading rhizomes that form dense vegetative mats

(Eleuterius, 2000). It can thrive in infrequently inundated zones near the high water line but can 

also withstand frequent flooding (Barnett and Crewz, 1990). Saltgrass may be more resistant to

environmental stressors, such as drought, than cordgrass (McKee et al., 2004), and can tolerate

high salinity and other harsh conditions (Brewer et al., 1998; Eleuterius, 2000). However, saltgrass

has been shown to be susceptible to decreased oxygen levels in the substrate and to increased 

flooding over time and may be vulnerable to sea-level rise (Donnely and Bertness, 2001).

Saltgrass has been used successfully in wetland-restoration efforts (Howard, 2003), and

many consider it to be a pioneer species in salt marsh development (Mitsch and Gosselink, 2000).

Research suggests saltgrass may compete for nutrients more effectively than other marsh species in 

nutrient-limited conditions (Levine et al., 1998). Opportunistic species, such as saltgrass, may 

colonize disturbed areas (Shumway, 1995; Coultas and Lasley, 2001). In the Gulf Coast marshes,

saltgrass commonly occurs as a colonizing species after disturbance, such as wrack deposition after

a storm (Clewell et al., 1999).

Saltgrass is a clonal species, spreading vegetatively over large areas. A strength of clonal

reproduction lies in the benefits to both parent and offspring clones from the integration of

available resources through inter-connecting rhizomes (Pennings and Callaway, 2000; Shumway,

1995). A single saltgrass clone may cover a large area and, as a dioecious species, produces only 

male or only female flowers. Female plants tend to dominate lower-elevation sites, and female

seedlings are more likely to survive flooded conditions (Eppley, 2001). These traits may further

influence the character of a particular site and its suitability as habitat.

Saltgrass is a food supply for many birds and small mammals and provides habitat to 

species besides the Florida salt marsh vole (Barnett and Crewz, 1990). As habitat, it is associated 

with the southeastern beach mouse, clapper rail, seaside sparrow, cinnamon teal, long-billed 

curlew, wandering skipper butterfly, and others.

Study Area

The sites of known Florida salt marsh vole populations are in Levy County on the Gulf

coast of Florida, near Cedar Key (Figure 1). The intertidal zone of the Lower Suwannee NWR is

characterized by an open coast and is protected to the west by emergent oyster reef (Orlando et al.,

1993). The Suwannee Estuary marsh coast is part of the Big Bend marsh coast extending to the

north and south along Florida’s Gulf Coast (Fretwell et al., 1996). The region is characterized by a

shallow offshore shelf, low wave energy, 1-m tidal range, low sediment supply, near-surface
3

limestone, and indeterminate flow from the Floridan aquifer (Raabe et al., 2004; Davis, 1997;

Montague and Odum, 1997).

The Suwannee River is a black-water river with an average annual discharge of 295 m/s

(Tillis, 2000; Siegel et al., 1996). Salinity variation in the estuary is most closely related to 

variation in river discharge, which reflects climatological conditions of the headwaters in southern 

Georgia (Orlando et al., 1993). High discharge typically occurs between February and April, when 

the plume extends south toward Cedar Key. The delta marsh and tidal creeks directly adjoining the

river support a greater variety of coastal-wetland species than is typical of the Big Bend (Clewell et

al., 1999; Coultas and Lasley, 2001; Raabe et al., in prep.). However, both known Florida salt

marsh vole sites were located farther to the south, where vegetation is more consistent with typical

Big Bend salt marsh (Raabe et al., in prep.).

The typical intertidal zone of the region is characterized by broad stretches of salt marsh,

remnant stands of coastal forest, meandering tidal creeks, and oyster bars (Raabe and Stumpf,

1997). Relict sand dunes, shell mounds, and exposed limestone outcrops provide minimal relief in 

the intertidal environment (Davis, 1997). Depending on elevation, flooding, wave energy, and

salinity gradient, the tidal marsh supports smooth cordgrass, common black needlerush, saltgrass,

and other high-marsh species and salt-tolerant species (Clewell, 1997; Montague and Weigert,

1990).
4

Figure 1. Study area for Florida salt marsh vole habitat, Levy and Dixie Counties, Florida.
5

Methods

Background

The mapping effort consisted of a re-evaluation of hyperspectral imagery acquired for

general habitat mapping, and ground surveys of the intertidal zone of the Lower Suwannee NWR

(Borstad Associates, 2002a; 2002b). The hyperspectral imagery was acquired in September 2002 

to map general habitats of the Suwannee River estuary and consists of 12 bands of data at 4-m

resolution (Borstad Associates, 2002b; Raabe et al., in prep.). Although the imagery does not

encompass the whole refuge, it covers the marshes from Sanders Creek to Barnett Creek (see

Figure 1).

Field surveys

Field surveys were conducted to evaluate accuracy of the mapping from remotely sensed 

imagery. Field records include Global Positioning System (GPS) positions, photographs, and field

descriptions of the 153 sites. Fieldwork was conducted in the summer of 2005 to canvas areas

from Johnson Creek to Shell Mound. Coordinates of known saltgrass sites were entered into a table

format and were displayed and prepared for use in a Geographic Information System (GIS). Field 

data were used to verify potential saltgrass sites derived from the imagery and to augment areas not

covered by the imagery.

Image Processing

Fourteen flight lines of hyperspectral imagery were reprocessed for saltgrass identification.

The original flight lines were reprojected from Albers to Universal Transverse Mercator (UTM),

zone 17R, WGS 84. A land model for each of the 14 flight lines was created for categorizing only

emergent and landward features. Two classification methods were applied, supervised 

classification and unsupervised classification. The supervised classification relied on known sites

for saltgrass training sites. Separability was determined by comparing ranges for saltgrass against

non-saltgrass sites and evaluating range of values for saltgrass sites in each band. Potential sites

were mapped, and areas adjacent to accessible tidal creeks were selected for field reconnaissance

on August 11, 2005.

An unsupervised classification was performed on all 12 bands of data for the 14 flight lines

using the land models. Existing field-verified locations were overlaid on the unclassified images to

select classes that could represent saltgrass sites. The process was repeated for each flight line.

Potential sites were mapped, and areas adjacent to accessible tidal creeks were selected for field 

reconnaissance on August 24, 25 and 26.

Results

Mapping

The supervised classification was unsuccessful. Field verification showed saltgrass was

present at less than 10% of the identified sites. Separability of saltgrass from known sites was

complicated by a wide range of site conditions and plant-community variations. Some saltgrass
6

sites had similar reflectance to non-saltgrass sites, and saltgrass did not have consistent range of

values from one site to another.

The unsupervised classification was relatively successful. Potential saltgrass sites derived 

from hyperspectral imagery were evaluated with field data, and an error evaluation was conducted 

to determine the accuracy of the final map (Table 1). Approximately 62% of known saltgrass sites

was successfully mapped. This means that 38% of the known saltgrass sites was not identifiable

with the imagery. However, other features were less frequently mapped incorrectly as saltgrass,

with a low error of 8%.

These potential saltgrass sites are mapped in Figure 2. No sites were mapped in the delta

region of the Suwannee intertidal zone. Saltgrass was noted in field reconnaissance in this area but

always as a thin understory. Some differences in marsh-reflectance characteristics and artifacts

from flight patterns are inherent in this product.

Table 1. Error matrix for potential saltgrass sites derived from hyperspectral imagery.

# Sites Mapped # Sites Not Mapped Total # Sites % Mapped

# Saltgrass Sites 33 20 53 62%

# Non-Saltgrass 8 95 103 8%

Total # Sites 41 115 156

Field Reconnaissance

Several extensive saltgrass sites were identified in the process of field checking the imagederived sites. Sites covering the largest area and sites with extensive small patches mosaicked in 

the marsh were selected for mapping and descriptive purposes. Positive field-checked saltgrass

sites were distributed north and south of the river delta marsh, but not within the delta marsh itself.

Some sites were dominated by saltgrass, others were a saltgrass mix, and in other areas saltgrass

occurred as small patches or single stems within the larger salt marsh mosaic.

Figure 3 shows the location of 26 known saltgrass sites. Although the presence of saltgrass

was identified at other locations, each of the selected sites was either an extensive area of saltgrass

or surrounded by many pockets of saltgrass in the larger salt marsh mosaic. These sites represent a

range of saltgrass-habitat conditions. A summary of the selected sites is presented in Table 2 with

brief field descriptions and links to photographs of the sites.

Saltgrass often occurred as part of a mix of other grass species, either as a dominant or as an 

understory vegetation. Frequent co-occurring species included three-square sedge or glassworts and 

less frequently, cordgrass, black needlerush, or sea oxeye (Borrichia frutescens). Canopy heights of

20 – 85 cm were observed in the field. Many of the sites were observed at the beginning or during

the 2005 blooming season, which occurs from spring through late fall. This may explain the taller

stems.
7

Figure 2. Potential saltgrass sites north (a) and south (b) of the Suwannee River mouth derived from

hyperspectral imagery.
8

Figure 3. Known saltgrass sites north (a) and south (b) of the Suwannee River mouth.
9

Table 2. Location (UTM 17 R WGS84) and description of known saltgrass sites.

Site # UTM E UTM N Creek/Location Description Photo links to images

Site 1 286393 3252655 Johnson Creek Black needlerush dominant with saltgrass

throughout area, east 11 m Johnson1.jpg

Site 2 286903 3252681 Johnson Creek Blooming saltgrass ~ 0.5 m tall along shore.

Mix with cordgrass 40 m SE. Johnson2.jpg

Site 3 286893 3251367 Sanders Creek

Saltgrass and three-square ~10 m to east

and patches extend along north and east of 

feature in a mosaic with black needlerush.

Saltgrass up to ~85 cm tall and 66% of 

canopy.

Saltgrass_bloom1.jpg

Site 4 287761 3251589 Sanders Creek

Blooming saltgrass with cordgrass and

black needlerush 30 m south and east.

Saltgrass is dominant to south. Saltgrass is

~ 50% of the canopy and 0.75 m tall.

Saltgrass_bloom2.jpg

Site 5 287308 3251118 East of Little

Pine Island

Saltgrass mixed with cordgrass and threesquare to south and east. Very muddy site. Sanders1.jpg

Site 6 287179 3251007 East of Little

Pine Island

Saltgrass mixed with smooth cordgrass and

three-square. Saltgrass in understory up to

~50% canopy.

no photo

Site 7 288795 3252299 Sanders Creek

Saltgrass patches mixed with wrack and

black needlerush to south and SW, around

hammock and along creek meanders.

Saltgrass is ~50-60% of canopy.

no photo

Site 8 287348 3250474 Bumble Bee

Creek SE

Large patch of low saltgrass with scattered

scrub extends east and south 150 m and

north 50 m. Firm substrate.

Saltgrass1.jpg

Site 9 288356 3248844 Fisherman's

Cove

Large stretch of saltgrass. Some patches

mixed with three-square (see photo). To

east is edge with black needlerush and west

is elevated scrub line. Saltgrass extends to

south ~100 m. Shell hash along shore and

in substrate.

Fishermans.jpg

Site 10 288542 3248710

Back of 

Fisherman's

Cove

Patch of flooded saltgrass on shore that

extends north ~ 150 m.

Saltgrass_Flooded1.jpg

Site 11 298025 3248837 North Double

Barrel Creek

Flooded saltgrass and cordgrass at shore

and northwest 15 m to thin saltgrass with

wrack, leading to mix with black

needlerush mix. Mixed throughout with

floating wrack.

Saltgrass_Flooded2.jpg

Site 12 289584 3249348 North Double

Barrel Creek Steve Barlow trap site. Not visited. no photo

Site 13 289283 3247885 South Double

Barrel Creek

Dominant black needlerush with saltgrass

northeast 45 m. Patch extends north along

shore 100 m including a mound with sabal

palm and scrub.

no photo

Site 14 289551 3247495 North of Palm

Island

Saltgrass here up to 0.85 m tall with no seed

heads. no photo

Site 15 288730 3246420 Cat Island

Patch of saltgrass with three-square

bordered by black needlerush extends north

25 m to wrack line. Saltgrass feature is

broken by patches of wrack or black

needlerush but extends south and

southwest.

Cat_Island.jpg

Site 16 286741 3251913 East of Big

Pine Island

Saltgrass and black needlerush mix north

and west and along edge of hammock. Saltgrass2.jpg
10

Site 17 298675 3239692 Big Trout

Creek

Saltgrass patch behind scrub levee and

along edge of creek to north and west along

meanders. Mix with three-square and

cordgrass. Patches along creek to Site 18.

Big_Trout1.jpg

Site 18 298814 3239724 Big Trout

Creek

Saltgrass with cordgrass and three-square

south 50 m. Big_Trout2.jpg

Site 19 298844 3240084 Big Trout

Creek

Saltgrass patch on back of creek levee to

west 50 m and to the southeast. Saltgrass is

blooming, ~ 0.5 m tall and thick. Many

patches along this creek.

Big_Trout3.jpg

Site 20 298574 3237256 West of 

Erickson Creek

Saltgrass mix with cordgrass and threesquare, extends east 50 m, west 100 m,

south 50 m. Elevated marsh.

Saltgrass_bloom3.jpg

Site 21 297408 3234705 Long Cabbage

Island

Thin bands of saltgrass along back of 0.5

m-tall sandy levee with sea-daisy and

cordgrass in mosaic around meandering

creek and tidal impoundments.

Long_Cabbage.jpg

Site 22 298117 3234703 Raleigh Island

NW

Saltgrass patch west 50 m and southwest

100 m with male and female flowers ~0.4

m-tall and full canopy. Mix with cordgrass

and saltwort. Many grasshoppers.

Raleigh Island.jpg

Site 23 298020 3233603 Buck Island

South

Large saltgrass meadow extends to tree line

north, and ~ 200 m east and west.

Shoreline bordered by scrub. Mix with

cordgrass, sea oxeye and other low-growth

speces. Saltgrass is low (~0.3 m) and

blooming.

Buck_Island.jpg

Site 24 298403 3233017 Hog Island

West

Saltgrass, both male and female flowers, up

to 0.5 m mix with cordgrass, saltwort, and

glasswort south 45 m. Bounded to east by

oak/palmetto scrub, and to west is

shoreline.

Hog_Island.jpg

Site 25 298585 3240594 Big Trout

Creek

Saltgrass is patchy but consistent along the

creek. At low tide, these banks are

substantially elevated.

no photo

Site 26 290941 3251270 Bumble Bee

Creek South

Saltgrass in understory of morbid and

downed trees on firm, wet, and muddy

sediments and limestone outcrops.

Intermixed with black needlerush,

cordgrass, and salt scrub in patches

throughout area adjoining upper creek.

Bumble_Bee.jpg

On the Lower Suwannee NWR, saltgrass was common as a nearshore meadow, or behind or

along low natural levees, where the only sign of topography variation was a rough band of salt

scrub on elevated sand or shell hash. Saltgrass in the Lower Suwannee NWR does not appear to be

limited to locations adjoining obvious uplands, as described for Atlantic Coast wetlands. Only one

location, Site 26, occurs at the marsh interior. This location at the head of Bumblebee Creek is also 

the location of coastal forest die-off, where tidal flow has intruded and salt marsh species are

colonizing the substrate (Williams et al., 1999; Raabe et al., in prep.).

Conclusions

Potential habitat sites for Florida salt marsh vole were located in the Lower Suwannee

NWR by two methods, using saltgrass as an indicator of habitat suitability. Verified saltgrass sites

were located during field-reconnaissance efforts along tidal creeks north and south of the river.

Other potential locations were derived from imagery using an unsupervised classification. Saltgrass
11

occurred both as a dominant species and as an understory in mixed salt marsh sites. Where

dominant, it typically co-occurred with three-square or glasswort. Saltgrass also co-occurred with 

black needlerush, cordgrass, sea oxeye, salt scrub, and saltwort. It was found in a variety of

environments and substrates. Saltgrass occurred at shoreline and interior locations, on sand and

shelly deposits, on muddy marsh sediments, and on thin mineral sediments over exposed limestone

surfaces. Saltgrass frequently occurred on elevated marsh surfaces and near features with a slight

topographic rise. Saltgrass also occurred in flooded areas and was found in swales behind coastal

levees. The clonal, vegetative nature of saltgrass reproduction may facilitate persistence in lowelevation, flooded, saline, or other extreme environments. The parent plant can derive support

through rhizomes connected to a daughter clone with different resources and vice versa.

Mapping of saltgrass from imagery was hindered by the broad tolerance of the plant to a

variety of physical conditions and co-occurrence with various species from differing environments.

This widespread species co-occurrence is common in the marshes near the Suwannee River and is

attributed to localized variations in salinity and freshwater flow and patterns of colonization in 

disturbance patches (Coultas and Lasley, 2001). Changes in plant-canopy dominance may have

occurred during the last three years in response to change away from drought conditions (Clewell,

2000; Coultas and Lasley, 2001). As scientists learn more about the Florida salt marsh vole habitat

requirements, its life history, and home range, habitat may be better defined with additional

parameters.

The majority of identified saltgrass-dominated sites are north and south of the Suwannee

River, but not directly adjoining the river. Saltgrass was present in the marshes adjoining the river,

but occurred primarily as an understory species. The delta marshes have been shown to have a

stronger contribution of freshwater and brackish species and a higher tendency to flooding by 

freshwater (Bales et al., 2005; Coultas and Lasley, 2001; Raabe et al., in prep.). The presence of

saltgrass in different environments indicates that it may alternate as dominant, co-dominant, and 

understory species depending on conditions. For instance, during prolonged low river discharge or

drought conditions, the areas immediately adjoining the river may show increased cover of

saltgrass. Clewell (2000) documented the appearance or increase of saltgrass during the 2000

drought along transects in Lower West and East Passes. This suggests that the plant or seed stock 

was present and ready to colonize. The reverse may apply during times of increased freshwater

flow.

The recovery and protection of endangered or rare species relies on knowledge of habitat at

known locations. This mapping effort of potential habitats was limited to the ‘understood’

preference for a specific type of salt marsh environment, seashore saltgrass (Distichlis spicata).

More data on life history, mobility, and resource needs of the animal are needed.

This study raises several questions regarding the relation between the Florida salt marsh

vole and saltgrass as habitat:

1. Does the Florida salt marsh vole select for open, low-growth vegetation, where saltgrass

occurs with saltworts or glassworts, or will it be equally as likely to select a mix with 

sedge, blackneedle rush, or cordgrass?

2. Does the Florida salt marsh vole select for substrate, slope, flooding, or salinity 

characteristics of a site?

3. Does the Florida salt marsh vole have secondary or seasonal habitat preferences that must

occur near or alongside the saltgrass habitat?

4. Is the association of Florida salt marsh vole with saltgrass an association with 

environmental characteristics less suitable to predators or competitors?
12

5. Or is the association between Florida salt marsh vole and saltgrass indicative of a

commensal relation to another bird, mammal, or other organism also using the habitat?

6. Does the Florida salt marsh vole select for canopy characteristics of the plant or a product

of the plant, such as seeds, rhizomes, or salt extrusion?

7. Since saltgrass clones may occupy large areas, and a site may be dominated by male or

female plants, does Florida salt marsh vole prefer one to the other?

8. Will many small patches of saltgrass satisfy habitat requirements, or does the Florida salt

marsh vole require large areas of continuous saltgrass?
13

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Geological Survey Professional Paper 1656-B, xx p.

Barnett, M.R., and Crewz, D.W., 1990, An Introduction to Planting and Maintaining Selected 

Common Coastal Plants in Florida: Florida Sea Grant Report No. 97, 108 p.

Bordovsky, D.G., Choudhary, M., and Ansley, R.J., 2002, Survival of plant species as a function of

salinity and slope position: Texas Journal of Agriculture and Natural Resources, 15:81-90.

Borstad Associates, 2002a, Aerial Multispectral/Hyperspectral Data Acquisition in South and 

West-Central Florida Mission Report August 9, 2002: Sidney, BC, 33 p.

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West-Central Florida September 2002 Mission Report: Sidney, BC, 31 p.

Brewer, J.S., Rand, T., Levine, J.M., and Bertness, M.D., 1998, Biomass allocation, clonal

dispersal, and competitive success in three salt marsh plants: Oikos, 82(2):347-353.

Clewell, A.F., Beaman, R.S., Coultas, C.L., and Lasley, M.E., 1999, Suwannee River Tidal Marsh 

Vegetation and Its Response to External Variables and Endogenous Community Processes: Live

Oak, FL, Suwannee River Water Management District, 119 p.

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Drought in June 2000: Live, Oak FL, Suwannee River Water Management District, 15 p.

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Management of Tidal Marshes - A Model from the Gulf of Mexico: Delray Beach, FL, St. Lucie

Press, p. 77-109.

Coultas, C.L., and Lasley, M.E., 2001, Some soil properties and plant relationships in marshes of

the Suwannee River delta: Florida Scientist, 64(2):139-147.

Davis, R.A., Jr., 1997, Regional coastal morphodynamics along the United States Gulf of Mexico:

Journal of Coastal Research, 13(3): 595-604.

Donnely, J.P., and Bertness, M.D., 2001, Rapid shoreward encroachment of salt marsh cordgrass in 

response to accelerated sea-level rise: Proceedings of the National Academy of Sciences,

98(25):14218-14223.

Eleuterius, L.N., 2000, Tidal Marsh Plants: Gretna, LA, Pelican Publishing, 168 p.

Eppley, S.M., 2001, Gender-specific selection during early life history stages in the dioecious grass

Distichlis spicata: Ecology, 82(7):2022-2031.

Fretwell, J.D., Williams, J.S., and Redman, P.J., 1996, National Water Summary on Wetland

Resources: U.S. Geological Survey Water-Supply Paper 2425, Washington, DC, 431 p.

Howard, R.J., 2003, Native Plants for Effective Coastal Restoration: U.S. Geological Survey Fact

Sheet 090-03, Lafayette, LA. 2 p.

Levine, J.M., Brewer, J.S., and Bertness, M.D., 1998, Nutrients, competition and plant zonation in 

a New England salt marsh: Journal of Ecology, 86(2):285-292.

McKee, K.L., Mendelssohn, I.A., and Materne, M.D., 2004, Acute salt marsh dieback in the

Mississippi River deltaic plain - A drought-induced phenomenon?: Global Ecology and 

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Photographs

Site 1 - Johnson1.jpg

Site 2 - Johnson2.jpg
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Site 3 - Saltgrass_bloom1.jpg

Site 4 - Saltgrass_bloom2.jpg
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Site 5 - Sanders1.jpg

Site 8 - Saltgrass1.jpg
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Site 9 - Fishermans.jpg

Site 10 - Saltgrass_Flooded1.jpg
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Site 11 - Saltgrass_Flooded2.jpg
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Site 15 - Cat_Island.jpg

Site 16 - Saltgrass2.jpg
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Site 17 - Big_Trout1.jpg

Site 18 - Big_Trout2.jpg
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Site 19 - Big_Trout3.jpg

Site 20 - Saltgrassbloom_3.jpg
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Site 21 - Long_Cabbage.jpg

Site 22 - Raleigh_Island.jpg
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Site 23 - Buck_Island.jpg

Site 24 - Hog_Island.jpg
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Site 26 - Bumble_bee.jpg