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Editor’s Note: Swamp Story
This Editor's Note refers to a story about Sharon's
Atlantic White Cedar Swamp which ran in SFOC's Spring
2006 newsletter. The story precipitated a number of Letters
to the Editor to which the editor is responding in this note.
June 8, 2006
The picture in the print SFOC
Newsletter to which Katherine Byrne
objects was mistakenly taken of this area due to ease of access.
The scene is easily visible from the roadside. The Newsletter apologizes
for the confusion it may have caused. The picture has been removed
from this website but is still viewable by downloading the PDF
file of the SFOC Newsletter. Despite this photo error, the editor
of the SFOC Newsletter stands solidly behind the article.
The area that Katherine Byrne’s and Alice Cheyer’s
letters refer to—where the picture was taken—consists
of approximately 14 separate acres by the northeastern corner of
Sharon’s Atlantic white cedar swamp. This is a section where
there has been excessive and prolonged flooding (years long) in
this area due to its being isolated by railroad and street embankments
on all sides, beginning over 100 years ago with one railroad embankment
and later another embracing railroad spur to service Lake Massapoag’s
ice industry. At different times these 14 acres were drained and
at times flooded due to artificial, uncontrolled or intentional
events. Hence, water level history within this area is not representative
of the Cedar swamp.
Some might read the article, and incorrectly conclude, as Katherine
Byrne seems to, that swamp restoration would mean permanent high
levels of standing water. Actually the ideal goal is to divert
water into the swamp but with due control over water levels in
order to mimic the natural periods of higher and lower water most
conducive to cedar growth and regeneration. Water level control
would also involve—as the article points out—a careful
monitoring of human-use water pumped from the swamp-fed aquifer.
Tim Simmons of Massachusetts Natural Heritage & Endangered
Species Program writes:
“Some [towns in Massachusetts] are pumping
thousands of gallons per year with no detectable change [in swamp
water tables]
while
a wetland on Long Island was completely dried up and replaced
by upland vegetation as a result of excessive pumping.”
Restoration
of Sharon’s cedar swamp would not involve flooding
it. It would mean raising the water table to near the ground level,
the swamp floor (This is the ground in the hollows and not over
the mounds.) For short periods, higher water might be allowed in
order to mimic nature wherein temporary higher water levels inhibit
and prevent propagation of detrimental species which compete with
Atlantic white cedars. A study[1] by the Massachusetts Water Resource
Commission regarding a cedar swamp in Foxborough states:
“A threshold water table elevation
of 154.00 feet NGVD[2] is required for the peat
layer. This level is intended
to keep water within
one foot of the wetland hollow surface, as indicated by Atlantic
White Cedar Swamp experts as being within the range necessary
to maintain the ecosystem. This level will be monitored in both
the
shallow and deep peat layers at three locations, one at the
edge of the Atlantic white cedar swamp nearest to each of the Witch
Pond wells, and one at the nearest edge of the wetland restoration
area. Monitoring the deep peat layer is intended to allow observation
of potential drying from the base of the peat layer as a result
of hydraulic influence from the underlying aquifer. The peat
may
be subject to desiccation and compaction if continual dewatering
occurs.”
and
“…individuals with expertise in Atlantic
white cedar in Massachusetts were consulted to ascertain the hydrologic
conditions necessary
to maintain the Atlantic white cedar swamp ecosystem values
and functions. To maintain its habitat and to prevent invasion
and
dominance by other plant species, Atlantic white cedar swamps
require periodic inundation and a near-surface water table.”
Alice Cheyer criticizes the article as lacking background
and being an “opinion.” However, co-author Clifford Towner
has long and considerable experience managing Lake Massapoag. He
is
highly knowledgeable about the Lake-associated hydrology. He
is a current member of Sharon’s Water Management Advisory Committee
as well as the Lake Management Study Committee. Further, as a
very long-time Sharon resident and outdoorsman he has observed the
cedar swamp over a long period (40 years) of time. The editor
believes
Mr. Towner qualifies as an “expert.”
The editor has also contacted the Sharon Water Department. They
maintain that drainage ditches are a main culprit as far as the
ecologically damaging low water table in the swamp. But ditches,
combined with drawdown from well pumping (Sharon’s average
is over 1 million gallons per day.) and increased transpiration
from invading upland deciduous trees and shrubs (which can cancel
out 17 to 22 inches worth of rainfall per year) all conspire to
keep swamp water table levels too low for too long—especially
in the drier months—for cedar health and success.
The editor questions a second-hand citation in the letter of
Katherine Byrne. In the study she cites:
FM-East agrees with the
opinions expressed by Bruce Sorrie relative to the proposal to
restore the red maple Atlantic white cedar
swamp and cites Motzkin (1991): Increased water levels caused
by human
interference with normal drainage patterns appears to be the
single factor most frequently responsible for recent site degradation.
Glenn
Motzkin’s 1991 publication, Atlantic White Cedar Wetlands
of Massachusetts does not mention Sharon and does not refer to
any Sharon site. Motzkin is referring to a list of sites throughout
Massachusetts and his meaning is that, on average, a majority
(but by no means all) of cedar swamps have suffered from flooding.
Alice Cheyer cites a WRPB study done in the year 2000 but she
does not mention that it also stated “Portions of this
250 [3] [sic] acre swamp are dying due to
ditching and drawdown of groundwater
levels.”
As SFOC Newsletter editor, I verified the facts of Mr. Towner’s
article prior to publishing. Following publication, and in
view of the objections of Ms. Byrne and Ms. Cheyer, I undertook
to explore the
swamp myself. The new pictures on this website were taken during
that walk. There were few living cedars and those were of small
size. I saw no seedlings or saplings. I saw many, many dead
cedars leaning and fallen. I also noted the rampant invasive upland
vegetation
which normally thrives in soil too dry for Atlantic white cedar.
A picture on this website’s home page shows a small dead
cedar growing alongside a towering live white pine. Most significantly,
the day of my walk was the day following a record rainfall
event. Amazingly, I found the swamp floor dry. (While a detriment
to cedars
it was a boon to me as I was not wearing boots and could proceed
dry-shod!)
As to Ms. Cheyer’s criticism omission of sources, they were
not included in the print version of the Newsletter due to space
limitations. They are now available with the online version of
the story. I
have compiled an even more extensive list of sources and quotations
regarding Atlantic white cedar swamps. (Available
on request, since there are many website links
in this list.)
Ms. Cheyer also has attempted to portray the cedar swamp as a source
of mosquito-borne disease by stating “cedar swamps are
habitat for the mosquitoes that spread the Eastern equine encephalitis
virus through bird populations.” This is extremely alarmist
and misleading. The cedar swamp certainly has no monopoly on
the mosquitoes that transmit these diseases. There are many
other breeding
places—other wetlands, waters, backyard birdbaths and
even old tires. If wetlands and bird carriers were a threat
should we
fill all wetlands and destroy all birds? In reality the disease
threat is miniscule and, as with shark attacks, greatly exaggerated.
Last year there were two cases of EEE in Massachusetts and
no cases of West Nile Virus.[4]
Ms. Cheyer also notes: “Six years ago there was intense disagreement
over whether a new well could be sited on Chase Drive near
the cedar swamp without affecting it by pumping; that debate is
ongoing.
I do not think SFOC should involve itself uncritically on any
side of that debate.”
The editor contends that the proposed well site debate does
not affect the facts of the article—that overall average
swamp water tables are too low to sustain the cedar swamp.
The article
does not take sides on any issues, just as stating that the
moon is full on some nights would not involve “taking
sides” on
a debate concerning street lighting.
The editor stands by the article. If it has aroused controversy,
it has also aroused interest and so much the better.
Footnotes:
[1] http://www.mass.gov/dcr/waterSupply/intbasin/docs/FOXDEC.DOC
[2] NVGD means, essentially, sea level.
[3] 250
acres is the area where this preliminary study focused. Sharon’s
entire cedar swamp comprises about 600 acres.
[4] http://www.mass.gov/dph/media/2005/pr0906.htm
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