| |
 Beach
Dune Community
The beach dune community consists of two distinct plant associations.
The hardy pioneer plants, which are able to withstand the alkaline soil,
wide temperature fluctuations, salt spray, strong winds, and other harsh
environmental factors, colonize the foredune. This association is dominated
by sea oats. The sea oats are able to survive both partial burial by sand
and exposure of the root system when sand is blown away. The extensive
root system of this plant aids in dune stabilization. Sea oats are the
'glue' that holds the sandy island in place. On the protected lee side
of the dune is a large variety of plants, including beach grass, bunch
grass, prickly-pear cactus, and golden aster.
 Interdunal
Community
The interdunal community typically exists between the protected lee side
of the primary dune and the secondary dune ridges. This community has
a large variety of species depending upon elevation and soil moisture.
In higher areas, the vegetation is composed of grasses and broad leaved
plants. In low meadowlike areas where the water table is close to the
surface, species diversity increases. The moist interdunal areas are occupied
principally by Juncus scirpoides, with panic grass found in wetter
areas.
 Upland
Woody Community
In wider sections of the barrier islands there are wandering interior
dunes and dune ridges. Eventually, as these wandering dunes move farther
and
farther inland, away from the force of the wind, plants gain foothold
on the dunes and movement is slowed. This area is distant enough from
the wind and salt spray to provide adequate protection for the vegetation.
These higher and more stable inland dune ridges are dominated by woody
vegetation. The dune crests are dominated by gnarled scrub live oak; however,
the bulk of the vegetation is found on the lee side of the dunes, rosemary
is conspicuous on many dunes.
The pineland
community is found on the higher portions of several of the offshore barrier
islands, Horn Island has the largest pine area, and there are smaller
pine stands on East Ship Island and Petit Bois Island. The pine land community's
predominant species are slash pine, sand pine, scrub oak, rosemary, saw
palmetto and yaupon holly.
Salt
Marsh Community
All of the offshore islands have saltwater marsh areas distributed in
the protected waters. These marshes are generally divided into three zones:
high marsh, brackish marsh, and tidal marsh. The high marsh usually occurs
on level ground at an elevation of about one meter above mean sea level.
This area is inundated only during the highest tides, but dense mats of
salt-marsh grass keep the soil moist almost continually by shading it
and lowering the rate of evaporation. The plant species in this zone are
generally less salt-resistant than those in lower marsh areas.
The lowest
marsh zone, the tidal marsh, is inundated by the tides twice daily, and
it is the most productive of the marsh zones. The predominant vegetation
in these areas is black rush, marsh spike grass, and saltwort. Black rush
dominates marsh areas around lagoons and ponds that are periodically open
to the sound.
Back
to Top
|
|
