Topping
trees is perhaps the most harmful tree pruning practice known. Yet despite more
than 25 years of literature explaining its harmful effects, topping remains
a common practice. This information explains why topping is not an acceptable
pruning technique and
offers some better alternatives.
What is Topping
Topping Stresses Trees
Topping Causes Decay
Topping Makes Trees Ugly
What
is Topping?
Topping
is the indiscriminate cutting back of tree branches to stubs or lateral branches
that are not large enough to assume the terminal role. Other names for topping
include "heading", "tipping", "hat-racking" and
"rounding over."
The most common reason given for topping is to reduce the size of a tree to enhance a view. It is most amazing that people will happily top their trees, most probably to the trees detriment, only to get a view of distant trees.
Topping
Stresses Trees
Topping often removes 50-100% of the leaf-bearing crown of a tree.
Since the leaves are the "food factories" of a tree, this can temporarily
"starve" a tree. The severity of the prunning triggers a sort of survival
mechanism. The tree activates laten buds, forcing the rapid growth of multiple
shoots below each cut. The tree needs to put out a new crop of leaves as soon
as possible. If a tree does not have the stored energy reserves to do this,
it will be seriously weakened and may die. The Town of Beech Mountain requires
only 20% of a tree be prunned (not topped).
The stressed tree is more vulnerable to insect and disease infestations. Large, open prunning would expose the sapwood and heartwood to attack. The tree may lack sufficient energy to chemically "defend" the wounds against invasion. Some insects are actually attracted to stressed trees by chemical signals.
Topping
Causes Decay
The preferred location to make a pruning cut is just beyond the branch
collar at the branch's point of attachment. The tree is biologically equipped
to close such a wound provided the tree is healthy enough and the wound not
too large. Cuts made along a limb, between lateral branches, create stubs with
wounds that the tree may not be able to close. The exposed wood tissues begin
to decay. Normally a tree will "wall off" or compartmentalize the
decaying tissues, but few trees can define the multiple severe wounds caused
by topping. The decay organisms are given a green path to move down through
the branches.
Topping
Makes Trees Ugly
The
natural branching structure of a tree is a biological wonder. Trees form a variety
of shapes and growth habits, all with the same goal of presenting their leaves
to the sun. Topping removed the ends of the branches, often leaving ugly stubs.
Topping destroys the natural form of a tree.
Without
the leaves (up to six months of the year) a topped tree appears disfigured and
mutilated. With the leaves, it is a dense ball of foliage, lacking the simple
grace. A tree that has been topped can NEVER fully regain its natural form.
Topped trees are prone to breaking and can be hazardous. Since topping is considered to be an unacceptable pruning practice, any damage caused by branch failure of a topped tree may lead to a finding of negligence in a court of law.