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People often want a
tree to be smaller because it has grown too big. "Too big for what?"
we generally ask. The usual response
is that the tree has become dangerous and could blow over and fall on
the house. After performing a risk assessment we can
determine if the tree is safe.
You may still insist that the tree be reduced in
size. The most professional response we can make is that this is an
unnecessary task not endorsed by Beechwood Tree Care Ltd. Reducing canopy
size stresses the tree because of the cuts required.
Unlike a thinning cut, a drop-crotching cut does not cut back to a natural
boundary, this means that decay can spread quickly inside
cut branches, for this reason it is best not to perform crown reduction
if at all possible.
In many instances, canopies cannot be properly reduced in size to the
extent desired and certain species such as Beech do not
lend themselves to crown reduction, without special techniques such as
pollarding.
Over pruning of the trees to create the desired effect, with heading and
drop crotch cuts, can initiate decay in the trunk or branches
and stimulate rapid epicormac growth that fills in the canopy as it quickly
grows to it’s original size.
It is very difficult to use crown reduction to permanently maintain a
tree at a smaller size without causing the tree to decline.
Consider pollarding to reduce and maintain the height if the tree is young.
However tree removal and replacement with a smaller
maturing plant may be the choice that minimizes the input of resources.
When a customer wishes to reduce the height, crown reducing is much preferred
to topping. Crown reduction should not be used to
reduce the chances of the tree blowing over in a storm. Thinning is the
preferred method to minimize storm damage of an otherwise
structurally sound tree. Crown reduction can be considered when the root
system of a large maturing tree has substantial decay
making it potentially hazardous or on a tree with a high rating. We would
suggest considering pollarding or planting a smaller
maturing tree for the site.
How is crown reduction achieved?
The objective is to make cuts so that the foliage is left intact on the
outer edge of the new, smaller canopy ideally, pruning cuts
should not be evident when you stand back from the tree after pruning.
Topping, shearing, tipping, and rounding over are not
appropriate techniques for reducing the size of the tree because they
compromise the tree’s structure and can cause decay.
We would recommend when removing more than 30% of the foliage, that you
consider dividing the job into 2 sessions, around
12 months apart to minimize sprouting and starch removal from the tree.
To reduce the size of a tree with drop-crotch cuts, we shorten the branches
that extend beyond surrounding branches.
This maintains the approximate original shape of the tree. The tree is
simply made smaller. The longest portion of the main
branches will be cut back to an existing,
smaller lateral branch that is large enough to assume the role of the
branch.
This is normally 1/3 to 1/2 the diameter of the removed branch. Excessive
sprouting accompanied by die back or decay often occurs
if you cut back to a branch that is too small. It
is unreasonable to expect more than about a 15-20 percent reduction in
size of
canopy from a properly executed crown reduction. This is a time consuming
technique and is more an art than a science.
Our professional arborists are proficient at this technique and can take
an ordinary tree and create a unique specimen.
It requires substantial talent to perform this operation; of course this
is a temporary measure because the tree will quickly revert
to its natural size. Crown reduction is
quoted as percentage of leaf space not volume or height. |
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