Coastal Hammock in Sebastian, Florida

A coastal hammock near Sebastian is the shady oak and palm forest on the highest, most stable ground of the barrier island across the Indian River Lagoon, behind the beach dunes and the low shrub strand.

The Indian River Lagoon National Estuary Program uses maritime hammock, maritime forest, tropical hammock and coastal hammock as names for the same thing: narrow bands of forest that grow almost only on stabilized barrier island back-dunes, inland of the primary dunes and scrub (One Lagoon). Its canopy is usually closed, which keeps the hammock floor shady and cool next to the open scrub and beach.

The Florida Native Plant Society adds the climate reason. These hammocks form on raised coastal land where the ocean moderates the weather, so they often look more tropical than hammocks farther inland; soils are sandy, fire is rare or absent, and the canopy is usually a mixed hardwood forest led by live oak (Florida Native Plant Society). That describes the woods on the lagoon side of State Road A1A between Sebastian Inlet and Wabasso.

The barrier island east of Sebastian shows the sequence plainly. A December 1990 Florida Natural Areas Inventory assessment of the southeast Florida coast explains that the herbaceous beach dune gives way to a shrubby strand, which grades into forest as salt spray off the ocean stops killing the plants' terminal buds (FNAI, 1990). At Sebastian Inlet that means sea oats on the dune, saw palmetto and shrubs in the strand, and a canopy that climbs toward the lagoon.

Around Sebastian Inlet, the 1990 state survey found live oak, cabbage palm and redbay in the canopy, with marlberry, nakedwood, pigeon plum and wild coffee below and tropical trees such as gumbo limbo mixed in.

The FNAI surveyors visited four sites within a few miles of Sebastian and recorded each one (FNAI, 1990). On the north side of the inlet, in what was then Sebastian Inlet State Recreation Area, they found an oak and palm hammock whose canopy rose from about 15 feet near A1A to 60 feet at the lagoon edge, with tropical species in both canopy and understory, more of them closer to the Indian River Lagoon.

North of the park, the site the report called North Sebastian Inlet held a 60-foot palm and oak hammock grading to pure palm by the mangroves, with a tropical patch in the center dominated by gumbo limbo, wild lime and torchwood. South of the inlet, the Sebastian Inlet South site had sea grape, gumbo limbo and pigeon plum as its main canopy trees. At the north end of the Jungle Trail, live oak and redbay led the canopy, and a shell mound by the mangroves was dominated by cabbage palms (FNAI, 1990).

Pelican Island National Wildlife Refuge, on the same stretch of the Jungle Trail, lists mangroves, live oaks and gumbo limbo among its upland plants, alongside gopher tortoises and bobcats (USFWS).

Sebastian's coastal hammocks mix temperate and tropical trees because the Sebastian Inlet area sits in a band of coast where oak forest with a tropical understory replaces the fully tropical hammocks of Palm Beach and Broward counties.

The 1990 assessment split the region's hammocks into two kinds: temperate, usually oak-dominated communities with tropical species in the understory, and tropical communities with little or no oak. It named nakedwood, a small tree with smooth orange bark, as the indicator of the mixed type, and reported it was not seen south of St. Lucie County or north of Volusia County, the stretch that includes the Sebastian Inlet sites (FNAI, 1990).

Freezes set the limit. The surveyors walked the Sebastian Inlet hammocks in the months after the freeze of December 1989 and recorded the damage: on the north side of the inlet, many tropical trees including inkwood, strangler fig and mastic had been killed back, and the gumbo limbo center of the North Sebastian Inlet hammock was resprouting. At another surveyed site the temperate live oak and wax myrtle came through the same freeze unaffected (FNAI, 1990).

Modern hardiness ratings agree. UF/IFAS rates gumbo limbo hardy only in zones 10B to 11 (UF/IFAS), while it rates live oak for zones 7B through 10B (UF/IFAS). A Sebastian hammock carries both, which is why a hard freeze thins its tropical layer and leaves the oaks standing.

Near Sebastian, coastal hammock can be walked on the Hammock Trail at Sebastian Inlet State Park, at Captain Forster Hammock Preserve on the Jungle Trail, and on the Pelican Island refuge trails.

Florida State Parks describes the Hammock Trail at Sebastian Inlet State Park as a mile-long nature trail under the shade of a coastal, subtropical palm and oak hammock and along the mangrove fringe, with plant identification signs along the way (Florida State Parks). The FWC birding trail lists the park at 971 acres with coastal strand, maritime hammock and mangroves on both sides of the inlet (Great Florida Birding and Wildlife Trail).

Captain Forster Hammock Preserve, one mile south of County Road 510 on the Historic Jungle Trail, is the county's best example. Indian River County says maritime hammock covers about 68 percent of the 110-acre site and calls it one of the last remaining mature maritime hammocks in the county; large live oaks there carry wild butterfly orchids and native bromeliads, and taking plants is prohibited (Indian River County). The FWC birding trail adds that spring and fall songbird migration brings veery, ovenbird and magnolia warbler every year (Great Florida Birding and Wildlife Trail).

At Pelican Island National Wildlife Refuge, the three-quarter-mile Centennial Trail winds through restored wetlands, tidal mangroves and hydric hammocks, the wetter cousin of the dry coastal hammock (USFWS trails). Farther north, Archie Carr National Wildlife Refuge, established in 1991 along 20.5 miles of shore between Melbourne Beach and Wabasso Beach, lists maritime hammock among its habitats (USFWS).

Little coastal hammock is left near Sebastian because it grows on the highest, most stable ground of the barrier island, the same ground most wanted for houses and roads along A1A.

The estuary program states the problem in terms that fit the A1A corridor east of Sebastian: because maritime forests occupy the most stable areas of barrier islands, they are attractive development sites, and land clearing removes most or all of the native cover, which is then often replaced with lawns and exotic ornamental shrubs (One Lagoon).

In 1990 the FNAI found the temperate-canopy hammock typical from Brevard to Martin counties relatively poorly represented on public lands, with only small acreages at Sebastian Inlet State Recreation Area and one other site. Its acreage table for the park listed about 30 acres of temperate and tropical hammock and 4 acres of tropical hammock. The largest and most mature privately owned hammock it rated, with its mangrove and strand edges intact, was North Sebastian Inlet (FNAI, 1990).

Invasive plants were already working at the edges. The report noted Brazilian pepper invading the mangrove border where ditching for mosquito control had disturbed it, Australian pine on spoil near the jetty, and papaya heavily invading the tropical hammock at North Sebastian Inlet (FNAI, 1990).

For a Sebastian yard, live oak and wild coffee are coastal hammock natives that UF/IFAS rates for salt, while gumbo limbo is rated only for the warmest Florida zones.

UF/IFAS says live oak reaches 60 to 80 feet tall and up to 120 feet wide, grows in zones 7B through 10B, and tolerates alkaline soils, salt and drought, the conditions of a sandy lot near the Indian River Lagoon (UF/IFAS). Wild coffee, the shrub the 1990 surveyors found under the North Sebastian Inlet canopy, grows 4 to 10 feet tall, wants partial to full shade, is moderately salt and drought tolerant, and is very cold tender north of zone 9 (UF/IFAS).

Gumbo limbo is the gamble. UF/IFAS calls it one of the most wind-tolerant trees but rates it hardy only in zones 10B to 11 (UF/IFAS), and the December 1989 freeze knocked back the gumbo limbo stand north of Sebastian Inlet. Native trees and shrubs for planting are listed under trees and shrubs on Digital Towns Market. Digital Towns Market is our marketplace. Plants growing wild at Captain Forster Hammock Preserve and inside Sebastian Inlet State Park stay there: taking plants is prohibited at the county preserve.