Coastal Communities and Processes: Beach and Dunes Introduction to Coastal Management

Coastal Communities Coastal Communities and Processes: Beach and Processes: Beach

and Dunesand Dunes

Introduction to Coastal Introduction to Coastal ManagementManagement

Coastal Communities and Coastal Communities and ProcessesProcesses

• Beach and DunesBeach and Dunes• Shrub Thicket and Maritime ForestShrub Thicket and Maritime Forest• Freshwater WetlandsFreshwater Wetlands• Tidal MarshTidal Marsh• Estuarine Waters/Sand and Mud Estuarine Waters/Sand and Mud

FlatsFlats

Barrier Island Barrier Island transect from transect from

ocean to soundocean to sound

Beach, Dunes and Shrub Beach, Dunes and Shrub ThicketThicket

Cumberland Island, Georgia

Dune FormationDune Formation

SandSand WindWind ObjectObject

• Elements required for dune Elements required for dune formationformation

Dune FormationDune Formation

Sand, moved by the process of saltation, accumulates around objects including vegetation and flotsam

American American Beachgrass Beachgrass (Ammophil(Ammophil

a a breviligulatbreviligulat

a)a)

Sea OatsSea Oats (Uniola (Uniola paniculata)paniculata)

Panic Grass Panic Grass (Panicum (Panicum amarum)amarum)

SaltmeadoSaltmeadow w

Cordgrass Cordgrass (Spartina (Spartina patens)patens)

Sea Elder Sea Elder (Iva (Iva

imbricata)imbricata)

Primary DunesPrimary Dunes

• Most Most seawardseaward

• UnmodifiUnmodified dunesed dunes

Secondary Dunes Secondary Dunes

• large large landward landward dunesdunes

• modified modified primary primary dunesdunes

Strand Line or Wrack Strand Line or Wrack LineLine

• Line of debris Line of debris at spring tideat spring tide

• Debris is Debris is called called “wrack”“wrack”

• Most dunes Most dunes form hereform here

Strand Line or Wrack Strand Line or Wrack LineLine

• Large quantities Large quantities of sand moved of sand moved across strandacross strand

• Common on Common on prograding prograding (growing) (growing) beaches beaches

• Rare on eroding Rare on eroding beachesbeaches

Dune EnvironmentsDune Environments

• Youngest strand lines lie most Youngest strand lines lie most seawardseaward

• Multiple dune ridges form as Multiple dune ridges form as strand lines are colonizedstrand lines are colonized

Oldest - - - - - - > Youngest

Dune EnvironmentsDune Environments

• Dunes and colonizing plants Dunes and colonizing plants grow in concertgrow in concert

Year 3Year 3Year 2Year 2Year1Year1

Dune Environmental Dune Environmental Conditions Conditions

• Low soil Low soil nutrients nutrients (N and P) (N and P)

• Desiccating Desiccating windswinds

• Blowing Blowing sandsand

Dune Environmental Dune Environmental ConditionsConditions

• Air and soil Air and soil temperaturtemperatures are es are highly highly variablevariable

Dune ProcessesDune Processes

• Unvegetated Unvegetated dunes “migrate” dunes “migrate” or move from <1 or move from <1 m to >15 m m to >15 m annuallyannually

• Migrating dunes Migrating dunes engulf engulf surroundingssurroundings Natural revegetation a long term processNatural revegetation a long term process

BlowoutsBlowouts

• Occur when Occur when vegetation vegetation mantle is mantle is destroyeddestroyed

• Difficult to Difficult to stop, once stop, once startedstarted

• Creates Creates environment environment called “slack”called “slack”

blowoutblowout

Natural and Man-Natural and Man-induced Impacts on induced Impacts on

DunesDunes• Oceanic Oceanic

overwashoverwash• ““erosion”erosion”

Washovers Washovers

Natural and Man-Natural and Man-induced Impacts on induced Impacts on

DunesDunes

• Off-road Off-road vehicle vehicle (ORV) traffic(ORV) traffic

• Sand Sand fencing: fencing: wooden, wooden, brush, treesbrush, trees

Salt Aerosol Impact on Salt Aerosol Impact on PlantsPlants

Source of salt aerosol (ocean side)

Source of Salt AerosolsSource of Salt Aerosols

Salt AerosolsSalt Aerosols

Salt Aerosol ImpactsSalt Aerosol Impacts

Salt aerosol effects on plants

Salt aerosol source

this side

Salt Aerosol Impact on Salt Aerosol Impact on PlantsPlants

• Generally decreases Generally decreases from strand line, from strand line, landwardlandward

• Highest on foredunesHighest on foredunes• Lowest in slacks and Lowest in slacks and

lee of duneslee of dunes

Shrub Thicket Shrub Thicket EnvironmentsEnvironments

• Early colonizers Early colonizers (survive low (survive low nutrients)nutrients)

• Best examples are Best examples are in dune slacksin dune slacks

• Reduced salt Reduced salt aerosol aerosol environment environment allows arborescent allows arborescent vegetation to vegetation to flourishflourish

Wax Myrtle Wax Myrtle (Myrica (Myrica pennsylvanica)pennsylvanica)

• Northern Bayberry Northern Bayberry is common in is common in thickets from Cape thickets from Cape Hatteras northward Hatteras northward into New Englandinto New England

• Bayberry candles Bayberry candles are made from the are made from the waxy coating on waxy coating on the berriesthe berries

Yaupon Yaupon (Ilex vomitoria)(Ilex vomitoria)