THE
EVANSTON SYCAMORE SCAM
Introduction
Evanston's Parks Department is currently cutting down 60
Sycamore trees on the grounds that they are a public hazard. The cutting program is proposed and
defended in a memo to the City Council and other department correspondence.
The evidentiary basis for this destruction of 60 trees is,
however, nil. The key points of the
Park's Department memo and communication to the City Council about Sycamores are
unsupported scientifically, unreferenced to the forestry literature, and the
data given about Evanston trees is inaccurate on multiple points. They do not thus constitute a
valid case for the tree removal program.
Two of my trees were condemned to be cut in this program. In addition to the errors of the
justification for the program, my trees do not fit the criteria that the
department defines for trees needing removal. I expect that many other property owners' trees also do not
comply with the definition.
Owners invest in the trees in some cases by planting them
and in most cases by watering, mulching, and pruning them. Therefore, we have a rightful vested
interest in the preservation of viable trees. As for the town, it ought also to have a vested interest in
the preservation of its tree resource and of the monetary resources of the
town, which derive from taxpayer dollars.
Keeping viable, long-lived trees in place is much more economical than
churning trees. Churning trees
cost money by taking out viable trees that cost money to put in, spending money
with employee time, equipment, and fuel to remove them and then to replace
them, including the cost of a new tree.
Keeping the viable tree in place will be as much as 100 times more
economical than the churning.
Thus this churning that is going on is destructive of a
public resource and it uses up large amounts of public funds unnecessarily.
The
trees in question
The trees in question are known most commonly as Sycamores. Most are hybrids of Platanus
occidentalis (Indigenous Sycamore) and P. orientalis (London Plane Tree). Therefore I will use the term Sycamore
for Evanston's trees in question.
The Parks Department gives different terms for the trees in its list of
trees but these do not accord with the standard use of terms, nor are the department's
criteria for classifying species indicated. The Sycamores are commonly found in the central and
northeastern US in mixed hardwood forests.
Sycamore hybrids are generally found in nature on humid
land around rivers, lakes, and swamps.
They are rapid growers and attain sizes among the largest of all native
hardwoods. They also are of very
great longevity, sometimes hundreds of years, sometimes a thousand. The trees are favored as ornamentals
and plantation trees because of their attractiveness, ruggedness, and
resistance to urban conditions, weather, and disease. Their ability to spring back and rejuvenate from the routine
assaults and accidents of existence is legendary. Their mottled leaves and bark patterns, which tend to arise
as a response to colonization by seasonal microorganisms, were earlier
considered desirable aesthetic traits, though not so much lately. But fashions in aesthetic tastes must
not fell trees.
The problem
Parks Department claims that Evanston's Sycamore trees are
incurring an unprecedented pattern of cracking in the truck that the staff has
never seen before. The Parks staff claim that the degree of cracking of most of
the trees is such as to compromise the survival of the trees due to the
potential for decay in the crack and the harm by the cracks to the trees'
structural integrity.
The department's statement that they had never seen such
cracks before shows how little observation the staff of the department has done
of trees in the town. Anyone
owning a mature Sycamore in our region will likely be familiar with this
phenomenon, though not our Parks Department arborist, strangely. Such cracks
are common in our trees and among Sycamore trees elsewhere in the seasonal
temperate zone.
The department does not state what about the trees
constitutes a public hazard but, presumably, they assume that the trees with
cracks will die sometime soon and that the dead trees or their branches might
fall on someone and hurt them. The
department, however, cites not a single example of Sycamores with cracks dying or
falling one anyone, and I also was unable to find any examples in the
literature or on google searching.
The department's description of the cracks as illness and
abnormal is wrong. Sycamores in
temperate seasonal regions regularly have the cracks, as I mention. The species have comparatively high water
content and thinnish bark, and therefore change more in volume through the
seasons than many trees.
The department describes the ridges that cracks lie on as
growth ridges but this description is in error. The cracks are not sited on growth ridges, which are smooth,
vertical elevations, but on the rough callus growth arising from prior cracks
that healed. Trees with no cracks
have no such ridges. These ridges
show that the trees cracked before and healed.
The department's statement that the cracks this year are
unprecedentedly large is not correct.
Most of the trees with cracks this winter have longer ridges than the
cracks. Since the ridges are
calluses from prior cracks, most cracks are smaller than those of prior years. Even those that might be larger than
prior years would not be a threat to the tree's life.
The department claims that cracks harm the tree by causing
decay and/or by harming the tree's structural integrity, especially if the
crack is near the base of the tree.
This is wrong, as the older the Sycamore, the more healed cracks it has,
not the reverse. The Sycamore's
survival is not normally harmed by either decay or mechanical weakness from the
radial cracks, according to the literature. This is because 1. The Sycamore is rarely killed or
significantly weakened by microbial attack but recovers within the same year of
occurrence; 2. because Sycamore wood's strong tensile strength from its
cross-linked fibers makes the trunk and limbs resistant to mechanical damage
and breakage; and 3. the Sycamore's capacity for vigorous growth causes it to
re-grow lost or damaged tissue readily.
The current scientific classification of the Sycamore
(Platanus occidentalis and its hybrids) cites the bark and trunk cracks as
characteristic of the species, as an adaptation to the species' relatively high
seasonal water content changes and the strong fibrous interlinking of the wood.
Also considered a species characteristic is that older Sycamores have hollow
trunks, like many of our country's most memorable trees, like the northwest
cedars. Ridges, cracks, and hollows can be seen in the illustrations of
typical, mature, healthy Sycamores, as typical anatomical features. The Parks
Department claim that the winter cracks threaten the life of the trees because
the deep ones would lead to hollow trunks, therefore, could not be further from
the facts. A tree that developed the beginning of a hollow would be
acting normally.
Sycamores are documented in the literature as able to live
very long lives, as much as 2000 years, as I mention. They have few mortal
diseases and get replaced as ornamental specimens mostly because of what some
people feel is an aesthetic problem in the mottling that microorganisms such as
athracnose causes to the leaves and bark.
D'Agostino of the Parks Department claims that no trees in
urban settings can survive to the large size of maturity. Sycamores are among the tree species
most able to survive well in the pollution and high-stress environment of towns
and cities. His statement is
inapropriate to Sycamores.
Sycamores are prominent among the species that do live to advanced
maturity and very large size in urban settings. In fact, according to the literature, Sycamores commonly
reach 80 feet in height and 60 inches in diameter in urban settings, making the
species too big for convenient street planting, to some tastes. Because of its disease resistance,
rapid growth, and resistance to pollution, the tree successfully grows very
large and lives hundreds of years in urban settings. If Evanston had the wisdom to let its Sycamores be, future
generations of residents would have the benefit of some of the largest and most
handsomely structured and patterned trees in our country. Europe currently has much larger
Sycamores than the US does, primarily because Europeans are smarter about their
forestry resources than we are, but also because of the longer history there of
landscaping.
Evanston's
project to cut our Sycamores is out of line with local botanical gardens and
parks services and the literature
No scientific literature relevant to the Sycamore issues
is cited in the department's communications. D'Agostino claims that the department's plan is based on
information given by the Morton Arboretum as if that institution supported the
plan. However, the stance of the Morton
Arboretum is misstated by the Parks Department, since the Arboretum has no
plans to remove its cracked Sycamores, and simply noted that the cracks are
common. It is not the case that the Parks Department's consultation with the
Arboretum gave any support for the plant for mass tree removal. There is no record of the Arboretum
advising Evanston to cut down its trees, and for good reason.
Here is what the Arboretum botanist advised us to do: "watching
the cracks and waiting to see if they heal in warmer weather or get more
severe. As long as it's not a hazard, I'd wait for the spring to see how
it leafs out. The tree needs to heal itself."
In our next door neighbor town to the north, Wilmette, the
forester, wiser than ours, noticed a number of cracks but says "We don't
remove every tree that has a frost crack."
And Chicago park officials, where Sycamores also developed
cracks, said that they are waiting to see if the trees heal.
Only Evanston is hastening to destroy our trees. No other municipality is doing what
Evanston is doing because it is not the right thing to do. The trees simply have
what are normal anatomical features for their species in seasonal environments
such as ours. The trees are not
dead and have not been proved to be sick or dying. Their removal is unjustified. By doing this the department
is hurting our plantings by removing trees that may not now be fashionable but
that are amongst the most durable, vigorous, and hardy trees for our area. The cutting of the trees along Judson
Avenue has ruined the lovely allees
that accompany the street.
As for the "evidence" given for the department's
stance, the link in the department's memo is not to a scientific source on
Sycamore trees and their biological and ecological characteristics but just a
random, non-peer reviewed posting by somebody on other species of trees.
It in no way is information to justify the decision to remove all these
trees.
Evanston would be advised to consult professional forestry
literature on Sycamores, of which I cite several examples below. It notes
that Sycamores often develop splits in bark and cambium, but these regularly
heal and do not adversely affect the survival of trees. The wood of the
trees in fact has an interlocked fibrous structure that resists damage from
splitting, as I mentioned above. Furthermore, trees are rarely harmed by
insect or microbial attack except in crowded plantation conditions, according
to Rousseau 2010 of the Mississippi University State Extension Service.
The trees develop a strong structure of their own accord and rarely
require corrective pruning, according to Gilman and Watson 1994, who recommend
it for parkways. The trees coppice readily, recovering quickly and vigorously
to lost branches and other cuts. Broken or pruned branches re-grow
quickly and vigorously.
In sum, Sycamores, "strong, hardy, vigorous",
according to the USDA and forestry service, which is why they are some of the
longest lived trees and a very, very old species, to boot. Had people
raced around to remove trees when they developed their normal, species-specific
scars, there would be no very old Sycamores.
The department's justification for removal of my and
others' Sycamores are invalid scientifically and practically. Proof of
that is that Evanston is the only community that is doing this hasty, mass
destruction of Sycamores.
Selected
References
Gilman, Edward F. and Dennis G. Watson
1994 Platanus occidentalis, Sycamore. Fact Sheet
ST484, USDA Forest Service
Rousseau, Randall
2010 American Sycamore as a Biomass Species.
Mississippi University State Extension Service, Publication 2636.
Wells, O.O. and R. C. Schmidtling
1990 Platanus occidentalis, Sycamore. National
Forestry Service, Silvics Manual, vol 2. Hardwoods Agriculture Handbook
No. 654. USDA Forest Service, Washington, DC.
