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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