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Endangered: Sharon’s Atlantic White Cedar Swamp
by Kurt Buermann and Clifford Towner
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 The
Atlantic White Cedar Swamp west of Lake Massapoag lies atop Sharon’s
largest and deepest aquifer. Over the millennia, decaying vegetation
from the cedars has created a layer of peat up to six feet thick
called Freetown muck, which is one of nature’s best water
purifiers.
The white cedar swamp covers an area of over 600 acres. It accumulates
and purifies rainwater, which then seeps into the underlying aquifer
and flows out in all directions. It feeds the Canoe River, Beaver
Brook and Billings Brook aquifers, as well as the springs that
feed the lake. Sharon’s six municipal wells all trap water
purified from the cedar swamp.
Due to its high elevation, no streams or brooks flow into Sharon,
Sharon depends exclusively on rainwater. If the cedar swamp was completely
covered over, and no rain was allowed to fall upon it, Beaver Brook
and Billings Brook would become seasonal streams. The springs feeding
Lake Massapoag would decrease and the lake would stagnate. Sharon
would eventually run out of drinking water.
Atlantic white cedar trees require wetland conditions. Presently,
there are hundreds of dead cedars in Sharon’s cedar swamp.
These cedars are dead and dying because the water table has been
lowered by human activities such as ditching and pumping of municipal
wells. Sharon withdraws close to 600 million gallons per year from
the ground, largely for residential use.
Airborne heavy metals such as mercury and other industrial pollutants
accumulate in wetlands through rainfall and drainage. These pollutants
are removed from the water by many species of wetland vegetation
and the peat. This beneficial vegetation is being lost due to the
drying out of our cedar swamp.
 Many species of upland trees and brush now occupy space where standing
water once stood. Those species transpire water into the atmosphere
much faster than Atlantic white cedars.
Once the peat (Freetown muck) dries out it will change state and
no longer filter our drinking water.
Since 1997, Sharon has averaged over fifty-six inches of rainfall
each year so you can see our loss of wetlands, streams, etc is not
caused by a lack of rainfall.
This most valuable resource area could be protected and preserved
simply by diverting the Sharon Heights storm drains into the cedar
swamp, limiting further the hours of outdoor lawn watering and a
very aggressive water conservation effort.
Fact: Each year Sharon loses more wetlands and less water goes into
our drinking water aquifer.
Atlantic white cedar trees grow very, very slowly. Two hundred-year-old
trees have been found measuring only a little over half a foot in
height. These cedar trees can live as long as 300 years. If swamp
water levels average lower, the result is an influx of invading trees
and shrubs whose shade can easily stifle growth and regeneration
of the light-loving cedars. Water levels are critical since the roots
of the cedar trees themselves must be submerged for certain durations
of time or the trees will die.
A “poster child” of an Atlantic white cedar swamp might
well be the Hessel’s hairstreak butterfly. Cedar trees are
the sole food source for the larvae of these rare, emerald-green
butterflies. The cedar swamp is also an important breeding and
living area for birds. These include: downy woodpeckers, brown
creepers,
magnolia warblers, black-throated blue warblers and ovenbirds.
Water birds such as mergansers, wood ducks and green and great
blue herons
are often found in cedar swamps.
The fate of Sharon’s own Atlantic White Cedar swamp near Lake
Massapoag is a looming crisis, not only in terms of jeopardizing
a pure, toxin-free water supply for humans, but in preserving a unique
habitat for wildlife as well. Plants and animals bound to the ecology
of a cedar swamp are also direct indicators of the swamp’s
health.
Perceived changes in the populations or biology of the cedar swamp
ecosystem—such as the lamentable decline of spring peeper frogs
in Sharon’s cedar swamp—are warning indicators of the
swamp’s health. Some may minimize the importance of animal
life in special ecosystems such as Sharon’s cedar swamp, especially
the tiny creatures, but the animal life—especially the small
organisms, directly affects plant life—the very plants which
help to immobilize and filter out toxins which (mercury for example)
otherwise would find their way into Sharon’s water supply.
Nature works in a circular way. Any disruptions of the water-animal-plant
cycle may harm or even kill off the swamp. If the cedar swamp’s
freely-given gift of purified drinking water is lost, we will lose
a fascinating, intricate system of wildlife and plants, both rare
and abundant.
Find links to websites with more information on Atlantic
white cedar swamps in the Resources section.
Join SFOC on a walk in the Atlantic white cedar swamp, Sept.
23 at 1:00 p.m. See the Events list for
more details.
Read Letters to the
Editor about this article. Read an Editor's
Note responding to the letters.
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