An Atlantic white cedar swamp is a mysterious place of mossy hummocks rambling around the roots of dignified spires stretching skyward. If you’re unfamiliar with these fascinating wetland communities, picture towering cedars casting deep shade on the boggy, tumbled terra firma below.
In a typical year, standing water is present in hollows for more than half of the growing season. If you were to start from the conical tree top and climb downward you would descend through its branches of flattened twig sprays with scaly, shortened, deep green leaves. Eventually about halfway to earth in the diminishing light you would find fewer leaves and set foot on a soggy forest floor, sometimes sparsely graced with ferns.
But in sunny canopy gaps created by natural disturbance, dense shrubs may proliferate such as winterberry (Ilex verticillata), inkberry (Ilex glabra), highbush blueberry (Vaccinium corymbosum), and swamp azalea (Rhododendron viscosum). Swamp-loving red maples (Acer rubrum) are common associates, while pitch pines (Pinus rigida), Eastern hemlock (Tsuga canadensis), and yellow birches (Betula alleghaniensis) can occasionally co-occur as well.
As the sun’s rays filter through this vertical mosaic of patient branches and earnest leaves, naturally there’s not much light left for the moist, acidic soil below. Perhaps it’s this earthy collage of cool, damp, sponginess punctured by robust, fibrous, almost woolly tree trunks standing tall above that give our senses a brush with prehistoric times.
Atlantic white cedar trees (Chamaecyparis thyoides) actually create this very rare wooded wetland habitat found in a narrow band only within 100 miles of the coast along the eastern seaboard. One-third of their entire acreage occurs in Massachusetts. This globally vulnerable plant community has
been historically impacted by logging as its naturally rot-resistant timber made durable shingles and fence posts. In the 1800s, vast areas of these majestic 60-80 foot high trees were often drained, ditched and converted into commercial cranberry bogs. The pale interior wood, yellowish in hue, contrasts with the darker heartwood of its red cedar cousin that pioneers into drier, open uplands.
Today, the remaining Atlantic white cedar wetlands are threatened by climate change and hydrological changes relating to development of surrounding uplands. Incredibly long-lived, these cedars can age gracefully up to 1,000 years, but old-growth trees can no longer be found in Massachusetts. Encouragingly, some abandoned cranberry bogs if given enough time can recover into Atlantic white cedar groves just like at HCT’s Coy’s Brook Woodlands and Lee Baldwin Memorial Woodlands, both accessed off Lothrop Avenue in West Harwich. If you want to explore a boardwalk back in time through the largest locally accessible Atlantic white cedar stand, visit the Marconi Site of Wellfleet in the Cape Cod National Seashore.
Beyond their inspiring appeal, Atlantic white cedars serve as a haven for a variety of plants and animals, including some rare species. Hessel’s Hairstreak (Callophrys hesseli) is a bright green butterfly that is a State-designated Species of Special Concern, feeding upon Atlantic white cedar as its host plant. Another rare insect is the small, smoky blue-eyed, Ringed Boghaunter (Williamsonia lintneri) dragonfly, its abdomen encircled with orange stripes and designated as Threatened in the State.
Some of the white cedar groves that recover from fallow bogs also co-evolve into vernal pools. In fact, vernal pool visitors like spotted salamander (Ambystoma maculatum) and even the uncommon four-toed salamander (Hemidactylium scutatum) have been observed in the tannin rich, tea-colored waters of the Atlantic white cedar stand at HCT’s Coy’s Brook Woodlands.
Rare plants can also be found among Atlantic white cedar wetlands including native rhododendron (Rhododendron maximum) and dwarf mistletoe (Arceuthobium pusillum), a parasitic vascular plant that is a Species of Species Concern. Meanwhile, birds of conservation concern that depend on white cedar nesting opportunities include the colorful Northern parula warbler (Setophaga americana), a State Threatened species, Canada warbler (Wilsonia canadensis), black-and-white warblers (Mniotilta varia), and Northern saw-whet owls (Aegolius acadicus). Atlantic white cedars are also a favorite winter browse for white-tailed deer (Odocoileus virginianus) and their dense cover provides sheltered bedding areas during harsh winter conditions.
The ecological restoration of former cranberry bogs can offer an opportunity to restore Atlantic white cedar habitat. Local, state and federal partners have been working over the last 20 years to restore this rare habitat, planting over 17,000 Atlantic white cedars at one site called Eel River in Plymouth. Similar restoration projects have followed or are in the planning stages in southeastern Massachusetts.
Whether contemplating sites for active restoration of the stately Atlantic white cedars or preserving current stands that have returned on their own to recovering wetlands, HCT is striving to protect this priority habitat. With its ancient atmosphere of moist mossy hummocks pocked by pools of water as tall cedars quietly keep watch, it’s a setting that harks back to a primal era in a time-traveling way that only trees can tap.