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)