Gulf Coast Dune and Coastal Grassland

This system includes vegetation of coastal dunes along the northern Gulf of Mexico, including the northwestern panhandle of Florida, southern Alabama, and southeastern Mississippi. The vegetation consists largely of herbaceous and embedded shrublands on barrier islands and other near-coastal areas where salt spray, saltwater overwash, and sand movement are important ecological forces. This vegetation differs from that of other regions of the Gulf, and this region forms a natural unit with similar climate and substrate. There are a number of diagnostic and endemic plant species which characterize this system, including Ceratiola ericoides, Chrysoma pauciflosculosa, Schizachyrium maritimum, Paronychia erecta, and Helianthemum arenicola.

There are a number of diagnostic and endemic plant species which characterize this system, including Ceratiola ericoides, Chrysoma pauciflosculosa, Schizachyrium maritimum, Paronychia erecta, and Helianthemum arenicola (Johnson and Barbour 1990).

The vegetation consists largely of herbaceous vegetation and patches of shrublands on barrier islands and other near-coastal areas where salt spray, saltwater overwash, and sand movement are important ecological forces. This vegetation differs from that of other regions of the Gulf, and this region forms a natural unit with similar climate and substrate (Johnson 1997).

The natural coastal dynamics include the movement of sand from wind, tides, and storm surge. This includes transport of sand along the coast (primarily from east to west), and movement of sand by wind or water between the dunes, beach and subtidal areas, and the movement of sand from the foredunes to the interior. If not restricted by infrastructure or engineered hard structures, beaches and dunes can migrate as coastlines change over time in response to the action of wind and water. The Gulf of Mexico coast is affected by one tide per day. Coastal grassland develops as a barrier island builds seaward, developing new dune ridges along the shore which protect the inland ridges from sand burial and salt spray, or as a beach recovers after storm overwash and a new foredune ridge builds up along the shore, protecting the overwashed area behind it from sand burial and salt spray (FNAI 2010a). Wrack and seaweed deposited along the shore is an important source of nutrients for the coastal ecosystem, and helps promote revegetation in newly disturbed areas (Defeo et al. 2009). Fire is rare and local to small areas.

Threats include recreation, beach cleaning (removal of wrack), beach renourishment (if not planned and carried out in a way compatible with the beach ecosystem), sea-level rise, coastal development, and coastal engineering such as beach armoring, seawalls, jetties and other structures which interfere with sand movement and shoreline migration (Defeo et al. 2009). Many coastlines are starved of sand due to dams on rivers which restrict the transport of sand to coastal areas. This is the case for the Apalachicola-Chattahoochee River system and the Mobile-Tensaw River system. Coastal engineering hard structures reflect wave energy, constrain coastal sand migration and often lead to greater loss of beach and dune sand (Defeo et al. 2009). Structures such as jetties around inlets restrict the natural movement of sand, starving coastal ecosystems of sand. The developed residential and tourism infrastructure of coastal areas has restricted natural dune and beach migration. Increasing sea-level rise associated with global climate change will lead to more loss of beach, especially in developed areas where infrastructure such as seawalls, buildings and coastal roads restrict the potential for inland migration of the beach and dunes. Beach renourishment has been carried out on many beaches along the Florida coast. The use of sand for renourishment which does not match the grain size and composition of the beach to be restored can be a threat, especially where sand is applied deeply. This can be disruptive to the beach and dune ecosystem. Invasive exotic plants can alter beach and dune sand vegetation dynamics (FNAI 2010a). Oils spills associated with coastal and offshore oil drilling are a threat. Invasive animals include imported red fire ants (Solenopsis invicta) and feral hogs (Sus scrofa) which prey on the eggs of various animals (Defeo et al. 2009). Feral house cats, dogs, and coyotes are a threat to nesting birds and other small animals which occur in coastal habitats.

Coastal dunes along the northern Gulf of Mexico, including the northwestern panhandle of Florida, southern Alabama, and southeastern Mississippi.