Case Study 2
Tree safety and the public
| One of the biggest concerns to any tree manager
is the safety of trees to the public. When we encourage people into
our parks, we have a duty to ensure that those people using the parks
are not exposed to any unreasonable risks.
|
Although this party of school children are enjoying their lunch in this shady
spot provided by the London Plane trees on the left of the picture, the Horse
Chestnut on the right of the picture has serious defects, including a split in
the main stem union and extensive decay in the trunk’s base.
Naturally, such
trees are to be regularly inspected and removed where appropriate.
The Chestnut has since been replaced.
|
On a still bank holiday a large branch fell from an old Oak tree, which caused
a fatality. ACS was instructed to assess the circumstances surrounding the falling
of the branch in one of London’s best known and highly frequented parks. The park
is open to the public and contains a high number of ancient trees (in excess of
400 years).
The management of these highly valued specimens, which are more
susceptible to failure because of their old age and condition, is intense and
undertaken by well-qualified and experienced personnel.
The Oak from which the branch fell is fenced off to prevent further pedestrian access to beneath its canopy.
|
| ACS used highly sensitive decay detection equipment to test the extent of decay and
importantly, the extent of effective wood tissue deemed to be supporting the branch
that fell. It transpired that decay fungi had degraded the central heartwood of the
branch to such an extent that, in places only 2cm of sound wood existed. The extent of
decay is not always visually evident, particularly from ground level. ACS inspected
both the fallen branch and the stub from which it originated up in the canopy.
|
The pale coloured sap wood is narrow at the branch edges and although the darker
heartwood can remain effective, we found that the wood had degraded badly
and offered little in terms of structural support.
|
| The brown rot within the heartwood of this tree is fissured, dry and crumbly. This
is an indication, coupled with the host species and thin residual wall, that
Laetiporus sulphureus or ‘Chicken of the Woods’ fungus has developed within the
tissues to break it down. It is possible to that Fistulina hepatica (Beef Steak fungus)
was also at work, given the very brown nature of the wood stain. Both fungi produce
annual fruit bodies none of which were present during out inspections.
|
 |
| The investigations and conclusions of our report, assisted in the determining a
tree maintenance strategy including a process of continued tree inspections in
targeted areas and a modification to general tree management at the park.
|
|
Previous
|
|
Case Studies
The introduced Grey Squirrel is one of the most destructive pests to
woodlands in the UK and is particularly damaging to Beech, Hornbeam and Sycamore.
|
