Type of
Hazard that may indicate tree potential to fail.
Cracks
A crack is a deep split
through the bark,
extending into the wood of the tree. Cracks are
extremely hazardous because they indicate that
the tree is failing.
Weak Branch Unions
Weak branch
unions can occur
where branches are not strongly attached to the
tree.
They form when two or more similar-sized upright
branches grow so closely together that bark grows
between the branches, inside the union. This ingrown
bark does not have the structural strength of wood,
which results in a much weaker union.
Decay
Decaying
trees can be prone to failure, but
the presence of decay, by itself, does not indicate
that
the tree is hazardous. Advanced decay (wood that
is
soft, punky, or crumbly, or a cavity where the
wood
is missing) can create a serious hazard. Evidence
of fungal activity, including mushrooms, conks,
and
brackets growing on root flares, stems,
or branches,
are indicators of advanced decay.
Cankers
A canker is a localized area
on the stem or
branch of a tree where the bark is sunken or
missing. Cankers are caused by wounding or disease.
The
presence of a canker increases the chance of
the stem
breaking near the canker. A tree with a canker
that
encompasses more than half of the tree’s
circumference
may be hazardous even if the exposed wood appears
sound.
Root Problems
Trees with root problems may
fall
without warning. Soil
mounding, twig dieback, dead wood in the crown,
and
leaves that are off-color or smaller than normal
are
symptoms often associated with root problems.
Poor Tree Architecture
Poor architecture
is a growth
pattern that indicates weakness or structural
imbalance.
Trees with strange shapes are interesting to
look at, but
may be structurally defective. Poor architecture
often
arises after many years of damage from storms,
unusual
growing conditions, improper pruning or topping,
or other damage. Any abnormalities should be
examined by an arborist
knowledgeable with that species of tree.
Uneven Crown Growth
Uneven crown growth can come
as a result of a badly pruned a tree, or as a
result of storm damage. A tree with uneven crown
growth can become unstable and prone to fail.
Any potential danger to the Climber/Arborist
would be assessed on site prior to work being
carried out.
