Coastal Interdunal Swale

Presented byMarissa Rios

Breakdown

Coastal: near a coast

Interdunal: between sand dunes (ridges formed by wind, often on sea coast or in a desert)

Swale: low tract of land, often moist or marshy

FNAI Exemplary site

What is it?Category

◦Non-Forested Wetlands Marshes

Hydric, sandy soilStatus

◦G2 / S3

Anything else?Herbaceous or shrubby linear

depressions between dune ridges on sandy barrier islands

Varies from flooded to completely dry

Also called◦Interdune area◦Transitional zone◦Marsh, moist grassland, dense shrub,

damp flat

Where is it?Along sandy coastlines in FloridaGulf coastNortheast Atlantic coast south to

Cape Canaveral

What grows here?Vegetation depends on local hydrology,

substrate, and age of swaleMoist grasslands may be dominated by

◦Hairawn muhly (Muhlenbergia capillaris)◦Sand cordgrass (Spartina bakeri)◦Saltmeadow cordgrass (S. patens)

Damp sand flats will have a sparse cover of herbs such as◦Yellow hatpins (Syngonanthus flavidulus)◦Le Conte’s flatsedge (Cyperus lecontei)◦Engler’s bogbutton (Lachnocaulon engleri)

In South Florida◦Black mangrove (Avicennia germinans)

Wetter areas:◦Sawgrass (Cladium jamaicense)◦Cattail (Typha spp.)◦Needle rush (Juncus roemarianus)

Shallower areas:◦Umbrellasedge (Cyperus spp.)◦Carolina redroot (Lachnanthes caroliniana)◦Spadeleaf (Centella asiatica)◦Broomsedges (Andropogon virginicus, A.

glomeratus)Shrubby areas:

◦Wax myrtle (Myrica cerifera)◦Coastal plain willow (Salix caroliniana), Atlantic

coast◦Atlantic St. John’s Wort (Hypericum reductum),

panhandle

Hairawn muhly Sand cordgrass

Yellow hatpins

Cattails

Umbrellasedge

Broomsedge Spadeleaf

Wax myrtle

Atlantic St. John’s Wort

Black mangrove (S. FL)

Guana Tolomato Matanzas (GTM) Natural Estuarine Research Reserve

Similar to…Coastal grassland- stable sand

substrate, farther inlandBeach dune- coastal dune, can surround

CISCIS lack species tolerant of inundation

such as◦Seaoats (Uniola paniculata)◦Gulf bluestem (Schizachyrium maritimum)◦Crimson bluestem (S. sanguineum)

What lives here? Mammals

◦ Armadillo (Dasypus novemcinctus)

◦ Racooon (Procyon lotor)◦ Beach mouse (Peromyscus

polionotus) Reptiles

◦ Salt marsh snake (Nerodia clarkii)

◦ *Gopher tortoise (Gopherus polyphemus)

◦ Sea turtles Loggerhead sea turtle (Caretta

caretta) Green sea turtle (Chelonia

mydas) Kemp’s ridley sea turtle

(Lepidochelys kempii)

Amphibians◦ Limited information

Birds◦ Shorebirds and

wading birds common Clapper rail (Rallus

longirostris) Roseate spoonbill

(Platalea ajaja) Herons/egrets Terns Gulls, etc.

◦ Birds of prey may nest here Osprey (Pandion

haliaetus) Bald Eagle (Haliaeetus

leucocephalus)

Beach mouse

Gopher tortoise

Loggerhead sea turtle Osprey

Clapper Rail

Why are they there?

Standing waterSand for burrowing, movementGrasses/herbs/shrubs for cover

(nesting, mating, feeding, etc.)Stopover for migratory birds

Natural ProcessesOften inundated by local rainfallDynamicHydrology depends on height and

area of surrounding dunesLower dune ridges are better

protected from weathering succession of herbaceous species, ends with woody species

Natural Processes, Cont.

Storms may also level the dune, allowing it to be colonized by dune grassland community species such as spikerushes/spikesedges

Sand delivered/removed by waves and wind building and erosion

Salt water intrusion and sand movement following storms sets back succession halophytic species invade

Succession naturally kept in order

What about management?Threats:

Human encroachment/land conversionSalt water intrusion and sand burial may

leave swales vulnerable to invasion by exotic speciesTorpedo grass (Panicum repens)Chinese tallow (Sapium sebiferum)Brazilian pepper (Schinus terebinthifolius)Australian pine (casuarina equisetifolia)

Australian pine

Suggestions?

PreservationActive management:

◦Limit mechanical treatment, sensitive system

Examples:◦FL DEP- Beach Erosion Control

Program & more◦Other agencies/organizations have

similar programs

FNAI Exemplary SitesGulf Islands National Seashore (Okaloosa

County)St. George Island State Park (Franklin

County)Little Talbot Island State Park (Nassau

County)Anastasia Island State Park (Flagler

County)Cayo Costa State Park (Lee County)Rookery Bay National Estuarine Research

Reserve-Keewaydin Island (Collier County)

FNAI Exemplary site

Questions?