by Kat McConnell
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| Sea oats stabilize sand and aid in the formation of dunes |
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| Coastal sand dune communities |
This state park, located in St.
Johns County, faces the Atlantic Ocean, fronts the St. Augustine Inlet,
and abuts a salt run, giving visitors an opportunity to explore diverse
natural communities and the plants that inhabit them. On the upper beach
and foredune (first dune above the beach), the wide-ranging coastal
species are predominantly herbaceous. Sea oats (
Uniola paniculata) form
the backbone of the dune plant community; their rhizomes and stems trap
sand grains blown from the beach. Another grass that tolerates sand
burial is bitter panic grass (
Panicum amarum). Seacoast marshelder (
Iva
imbricata), is a succulent shrub found at the seaward base of the
foredune. When storms cause the dunes to erode, these dominant species
may occupy the dune face until sand has accumulated again.
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Ipomoea imperati (beach morning glory);
photo by Shirley Denton |
The
upper beach area seaward of the foredune is a less stable habitat,
frequently disturbed by high spring or storm tides, and is continually
re-colonized by annual species such as sea rocket (
Cakile lanceolata)
and Dixie sandmat (
Chamaesyce bombensis), or by trailing species like
railroad vine (
Ipomoea pes-caprae), beach morning glory (
Ipomoea
imperati), the salt-tolerant grasses seashore paspalum (
Paspalum
vaginatum), and seashore dropseed (
Sporobolus virginicus). Non-dominant
species found in the beach dune community include dune sunflower
(
Helianthus debilis) and shoreline seapurslane (
Sesuvium
portulacastrum).
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| Salt marsh foxglove; photo by Shirley Denton |
On the backside of the dune is a high
salt marsh. It graduates downward in elevation to become a low salt
marsh, where it fronts the inlet and extends into the Park’s salt run.
Dominant vegetation in the high marsh includes shrubs such as saltbush
(
Baccharis halimifolia); this is replaced with seaside oxeye (
Borrichia
frutecens) as elevation subtly drops. Grasses, including saltmeadow
cordgrass (
Spartina patens) and saltgrass (
Distichilis spicata), are the
most abundant of the herbaceous species in the high salt marsh. As the
landscape slope grades into a low salt marsh, correspondingly, the
plant species comprising the community consist of those more suited to a
brackish, saturated environment. Because this area is tidally
influenced, species adapted to inundation dominate the low marsh; these
include needlerush (
Juncus roemerianus) and saltmarsh cordgrass
(
Spartina alternifolia). Although species diversity is reduced within
the salt marsh, there are plenty of hidden gems in the
graminoid-dominated sub-communities. Among these are salt marsh foxglove
(
Agalinis maritima) and Virginia salt marsh mallow (
Kosteletzkya
pentacarpos). Mangroves, present along the inundated edge of the
estuary, provide opportunities for wading birds to forage and ospreys to
hunt. Speaking of wildlife, the dune and beach provide roosting,
foraging, and nesting for shore birds like royal and sandwich terns,
brown pelicans, various sandpipers, plovers, and black skimmers.
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| Anastasia beach mouse |
Most
notably, the dunes of Anastasia State Park provide the only known
habitat for the federally endangered Anastasia beach mouse (
Peromyscus
polionotus phasma), a tiny mammal whose average body length is
13.85–14.28 cm (5.45–5.62 in) - including its tail. Its two-tone pale
tan coat and white underbelly may be an adaptation that enables this
endemic species to avoid predation by blending into the sandy
environment. It inhabits the upper dune where scrubby vegetation offers
coverage and loose soil for burrows. Even when pregnant, this tiny mouse
weighs less than one ounce. The Anastasia beach mouse is mostly
nocturnal; the cover of darkness provides protection for its foraging
activities. Like the closely related southeastern beach mouse, their
favorite food is sea oats.
With over 4.5 miles of
hiking trails, a boardwalk and beach frontage, Anastasia State Park is a
fabulous and fun place to check out while you’re in town for the
conference. Amenities include concessions, bathhouse, campgrounds, and
restrooms.
Sign up for this field trip before it fills up!
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| Anastasia Island; the St. Augustine Lighthouse featured in the background. |
For more information about Anastasia State Park, please refer to this
link.
edited by Laurie Sheldon
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