THE ENDURING NATURE OF TUCKERNUCK

EDUCATION

NATURAL HISTORY PROGRAMS

The Tuckernuck Land Trust conducts natural history programs to heighten awareness of the island’s many natural wonders. These opportunities emphasize the importance of each participant’s role as a steward of Tuckernuck Island. During weekly summer programs led by TLT's Coastal Steward and guest naturalists, guided explorations into forests, grasslands, marshes, and the island’s surrounding waters, in addition to investigations focused on resident creatures, from shorebirds to sponges to bats, reveal intriguing curiosities of life.

NATURAL COMMUNITIES OF TUCKERNUCK

Tuckernuck’s natural communities can trace their distinction to the island’s very origins. When, during the last glacial episode, Tuckernuck Island was created by a terminal moraine, glacial till formed the higher elevations of rolling topography along the northern and central portions of the island. Glacial meltwater then drained seaward, forming outwash plains of well-drained sandy soils at lower elevations.

Oak Forest.  The northern and central portions of the island are dry oak forest, dominated by white and black oak. The gnarled shape and stunted height of these old trees reflect the strong winds to which they were subjected during their growing phase. It is within this oak forest that a recent inventory documented three lichen species considered to be old-growth indicators. This community also includes black cherry and the shrubs shadbush and black huckleberry.

Shrub Swamp, Bog, Wet Meadow and Ponds.  Wet communities are scattered around the island. Freshwater wetlands punctuate the oak forest and the island’s northern moraine. Shrub swamps, which occur in low-lying areas and also often buffer other freshwater wetlands, include some species also common to the oak forest, such as bayberry and northern arrowwood, as well as high bush blueberry. A sphagnum bog, lush masses of sphagnum moss in deep deposits of peat, creates an open area surrounded by a nearly impenetrable wet shrub thicket dominated by Virginia chain fern but also including cranberry, marsh St. John’s wort, and swamp candles. Ponds are surrounded by water-willow thickets and roosting Black-crowned Night Herons.  In one pond, a cattail marsh is decorated by ragged fringed orchid. An area known as the Slough, running along a narrow north-south axis near East Pond, represents these communities: resembling a glacial outwash pond, it features open areas with standing water, a cattail stand, and a small wet meadow.

Scrub Oak Barrens.  The scrub oak barrens transition between forest and grasslands. These stable communities form a dense canopy from species such as dwarf chestnut oak and smaller shrubs of northern arrowwood, bayberry, beaked hazelnut, whorled loosestrife, and Pennsylvania sedge.

Sandplain Grassland and Coastal Heathland. This community occurs on the south side of the island and in areas around the tidal ponds on the northwest and east ends. An example of a natural habitat that has been subsumed by development in much of the Northeast, Tuckernuck’s grassland occurrence is one of the largest remaining. Characteristic plants—little bluestem, spikegrass, asters, and goldenrods—are joined by sweet vernal grass and hair fescue, growth typical of post-agricultural pastures and evidence of Tuckernuck’s agrarian past. Because this habitat is increasingly rare, numerous state-listed rare plant species grow on Tuckernuck, including New England blazing star and sandplain blue-eyed grass. These grasslands support faunal species that are extremely rare in other parts of coastal New England and New York. Positioned adjacent to the shore and open ocean, grasslands serve as a significant refuge for both migrant species and species that compete well under severe maritime conditions.

Salt Marsh.  Surrounding North Pond and East Pond are high and low salt marshes dominated by cordgrasses and spike and black grasses. Sea milkwort, which had not been documented on Tuckernuck since 1907, was located during a 2008 inventory; though not rare in Massachusetts, it had never been documented on Nantucket. Unlike most salt marshes today, only one of Tuckernuck’s marshes was subjected to ditching, and only minimally. At both ponds, there are scattered occurrences of salt pannes, marsh depressions that retain water after high tides and foster salt marsh sea blite and glasswort. In addition, where tidal areas grade gradually into uplands, salt shrub communities fringe both of Tuckernuck’s ponds and most of the marsh with groundsel tree and saltmarsh elder.

Beaches and Dunes.  The driftlines along the back sides of the beaches feature a diversity of species, including sea rocket, orach, seaside goldenrod, and seabeach knotweed, in addition to oysterleaf, which is at its southern range on Tuckernuck. Where windblown sand accumulates in the east and west ends of the island, dunes are anchored by high densities of American beachgrass. The dunes are old and subject to frequent reworking by storms. Tuckernuck does not have older dune fields with more stable vegetation, but beachgrass has become dominant in areas on the southeast and west ends where sand has blown from the beach over glacial deposits.