FNPS 2013 Conference Field Trip: Anastasia State Park Hike

by Kat McConnell

Sea oats stabilize sand and aid in the formation of dunes
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.

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).

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.

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!

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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