arborist rpt tr-2018-03.pdfMichael L. Bench
> ; Consulting Arborist
(831) 594-5151
.l 7327 Langley Canyon Road
Y Prunedale, California 93907
APPROVAL
Signature
A Review of the Pruning of Two Trees
21915 Eaton Place
Cupertino, California
Assignment
I was asked by Piu Ghosh, Planner, City of Cupertino, to review the recent pruning of
two trees at 21915 Eaton Place, Cupertino, California. Mr. Phillip Willkomm, Code .
Enforcement Officer, City of Cupertino, obtained the permission to visit the site.
Observations
I observed the trees on March 23, 2016. At this time, the following individuals were in
attendance: Mr. Christof Krautschik, the home owner
Mr. Phillip Willkomm
Mr. Joshua Fengel, ISA certified arborist
Mr. _ (a neighbor, representing the home owner association)
And Myself
The subject trees are located in the front yard of Mr. Krautschik near the northeast corner
of the residence. This residence is the last house in a row of houses along the west side
boundary of this sub -division. This residence is, therefore, located at the northwest
corner of the development. The original plans for this development approved in 1994
identified this site as Lot 22, currently owned by Mr. Kautschik.
The two trees are described in a report dated February 17, 2016 (Site Observations,
February 3, 2016) by Mr. Fengel. Tree # 1 is an American sweetgum (Liquidambar
styraciflua) and Tree # 2 is a Brisbane box (Lophostemon confertus). Mr. Fengel's report
states that the trunk diameter of Tree # 1 is 5.3 inches DBH (Diameter at Breast Height)
and that the trunk diameter of Tree # 2 is 7.6 inches DBH. I did not measure the trunks of
these trees, but my observations accept Mr. Fengel's trunk measurements.
The approved Landscape Plans, L-1 and L-2 include Liquidambar styraciflua and
Eucalyptus on the plant list, but the Brisbane box (at that time given the botanical name
Tristania conferta) was not specifically stated. However, it appears that the Brisbane box
was the Eucalyptus species planted, because there are several of these existing along the
north perimeter of this development.
Prepared by Michael L. Bench, Site Observations:
Consulting Arborist March 23, 2016
21915 Eaton Place
Cupertino, California
The Landscape Plans show that a row of trees were required to be planted along the north
side property boundary as `Buffer" trees or screening trees. Two "Buffer" trees were
required for each of the Lots # 3, 4, 9, 10, 15, 16, 21 and 22. Mr. Kautschik's property is
Lot 22. These "Buffer" trees were a condition of approval and are required to be
maintained as "Buffer" or screening trees for life, unless the development would be
granted an exemption at a later time.
Mr. Krautschik stated that the trees were pruned by Oscar's Expert Tree Service, which I
shall refer in this report simply as Oscar. Mr. Krautschik reported that Oscar is an ISA
certified Arborist.
The following photo was found on-line from Microsoft Bing Maps and was provided to
me by Mr. Willkomm. This image was noted to have been taken on 4-9-14.
Tree # 1, the Liquidambar, is seen in the center of this photo. The top of Tree # 2, the
Brisbane box, is seen behind the Liquidambar. In this photo, Tree # 1 is approximately
twice the height of the corner eave of the house first story.
I view these trees to have been moderately dense, prior to pruning, compared to other
specimens of the same species in this development.
The recent pruning by Oscar has "Topped both Tree # 1 and # 2. Mr. Fengel stated that
Tree # 2 had been "Topped" approximately 7 years ago and that this recent pruning had
to be done to keep the inherently weak branches from breaking.
Prepared by Michael L. Bench, Site Observations: 2
Consulting Arborist March 23, 2016
21915 Eaton Place
Cupertino, California
Tree # 1 was also "Topped" by Oscar. Mr. Fengel described this as a way of managing a
co -dominant leader defect. It is here that I completely disagree. First of all, the angle of
attachment was not acutely severe, which is still present on the tree. Because of this less
acute attachment, the risk of breakage was low and certainly not a weakness that had to
be rectified at this time. Possibly in the future pruning to mitigate the weakness would
have been warranted, but not by "topping." The proper method of correction should have
been a procedure called "pruning for dominance" instead of "topping," which
permanently damages and compromises the structure.
The ISA Pruning Standards, Best Management Practices ANSI A300 (2008), specifically
advises against "topping" (P.16).
This photo to the left is a Brisbane box
tree. It is located between Lots 22 and
23. This specimen has rather typical
canopy density for a healthy specimen
of the species and it has not been
"topped".
By reviewing the 4-9-14 photo by
Microsoft Bing Maps (P. 2 of this
report), it appears that Tree # 2 prior to
pruning by Oscar was a little less dense
than this specimen.
The photo on the right here is Tree # 2 after
pruning. Although the canopy of Tree # 2 is
believed to have been less dense initially, it is
for that reason that it should have been pruned
less vigorously.
Apparently Oscar believed that this pruning
did not exceed the 25% live canopy loss
requirement. In my opinion, this pruning has
ignored the fact that less dense trees than
Prepared by Michael L. Bench,
Consulting Arborist
Site Observations: 3
March 23, 2016
21915 Eaton Place
Cupertino, California
typical for the species, must be pruned less vigorously. In this light, I view this pruning to
be excessive.
The ISA ANSI A300 Pruning Standards, Best Management Practices (P.28) defines How
Much is Enough, as follows: "The pruning dose is the percentage of foliage or buds
removed during pruning compared to the total amount of tree canopy. The percentage and
distribution of foliage (to be removed by pruning) shall be adjusted according to the plant
species, the age, the health, and the site." This means that the maximum of 25%, which
is generally regarded as the accepted amount for pruning, must be adjusted depending
on the condition and circumstances of an individual tree. It is obvious to me that this was
not taken into account during the pruning of these two trees.
Oscar pruned Tree # 2 in an
attempt to prevent branch
breakage. Although this was a
reasonable objective, it does not
alter the fact that by pruning the
tree so severe to address that
problem, it negates the fact that
this tree is a `Buffer" tree.
The "topping" of Tree # 1, as
seen here in this photo to
address the co -dominant leader
problem was not the best
management practice for this
tree. Much better options were
available.
The fact that both trees have
been "topped", they both must
now be pruned severely every
5-7 years for life.
Trees, having lost the
percentage of live foliage as
these two trees, will grow
slowly. It will take several years for them to regain their former density, if they are able
to do so at all. The ISA book, published by the Urban Tree Foundation, called Structural
Pruning: A Guide for the Green Industry (2013), by Edward S. Gilman, Bryan Kemp,
Nelda Metheny, and Jim Clark states that "excessive pruning depletes the reserves and
reduces the ability of the tree to photosynthesize more energy." This result is slow
growth and slow recovery.
Prepared by Michael L. Bench, Site Observations: 4
Consulting Arborist March 23, 2016
21915 Eaton Place
Cupertino, California
By the time these trees regain their density, assuming they are still capable of doing so,
they will require severe pruning again to address the fact that they have been "topped."
In my opinion, the usefulness of Trees # 1 and # 2 to serve as "Buffer" or screening trees
has been severely compromised. Should these trees be preserved, the regular reduction
of the top of their canopies effectively eliminates the screening ability of the second
story.
Recommendation
There is no good short term solution to address the buffer loss. The long term solution
would be to replace these trees with an evergreen species, well adapted to this area. The
less than ideal performance by one or more of the Brisbane box specimens (Lophostemon
confertus) within this development is not a reason to assume that the Lophostemon
confertus is unsuited for this location. The fact that there are several fine specimens
within this development indicates that the problem is not an incompatibility with the
species. It is fairly common for development sites, such as this one, that the poor
performance was a result of poor planting practice, of the lack of irrigation during the
planting period (from which trees usually never adequately recover), or of poor nursery
practices. Research studies have reported that 15%-20% of the trees provided for sale,
regardless of species, are "root bound" at the time of delivery. I have found that mass
plantings of an individual species at new developments usually contain a few specimens
of the mass planting that perform poorly not because of the species, but because other
factors. The Brisbane box (Lophostemon confertus) is certainly an acceptable species for
this area. One reason is that it is highly drought resistant. Although it is a Eucalyptus
species, it is relatively small at maturity compared to other Eucalyptus species.
Respectfully submitted,
Michael L. Bench, Consulting Arborist
International Society of Arboriculture Certification # WE 1897A
American Society of Consulting Arborists Member
Prepared by Michael L. Bench, Site Observations:
Consulting Arborist March 23, 2016