| Summary
Hundreds of urban trees are uprooted by high winds during
thunderstorms each year in Kuala Lumpur (KL), causing loss
of life and significant damage to property. A well-known dilemma
faced by any landscape manager is to preserve a tree’s
physical function as needed by the master plan, but at the
same time to set in place controls preventing the tree from
creating a future hazard during bad weather. In reality, the
practices are contradictory. Most of the time, a tree’s
natural shape must be changed in order to ensure its safety
for users, causing a change in its original function. This
study investigates the relationship between the risk of physical
damage during storms and tree size. Its aim is to define safe
size limits for trees, within which physical reformation is
not necessary.
| 
|
To achieve
this aim, an engineering approach to the uprooting problem
has been adapted for six tropical tree species commonly
planted in the urban environment of KL; three of the
species most susceptible to uprooting, and three of
the most resistant. Tree height, diameter, rooting stiffness,
and wood properties have been measured for each. Preliminary
analysis of measurements shows that tree height increases
more rapidly in trees that are sensitive to uprooting
than in resistant species. Pulling tests indicate that
rooting stiffness increases with tree size, but reaches
a maximum earlier in susceptible than in resistant species.
In contrast, there is no systematic relationship between
wood properties and susceptibility to uprooting. |
Results are being used to develop computer simulations of
tree failure for use by landscape managers to define safe
limits for tree size, setting a threshold beyond which tree
reformation is necessary. More importantly, this simulation
model will help prevent the uprooting problem as soon as the
planning stage, by allowing the appropriate selection of safe
species.
|
This 80-year-old tree was uprooted by single storm event.
With a trunk more than 40 m tall and 1.6 m in diameter
at breast height, only a really heavy machine can do
the same task.
|
Why did this pair of trees uproot, but other species
with a similar size nearby did not?
|
|
A pulling test for measuring rooting stiffness.
|
A bending test for measuring wood strength.
|
|
Home
Universiti Putra Malaysia
