Archive for January, 2016

The end of a big black pine…

Wednesday, January 27th, 2016

You may notice some temporary traffic lights outside the arboretum today and tomorrow (27 and 28 January 2016).

We have arranged for this traffic management to be put in place as we need to work above part of the A433 road that runs along our boundary.

The work at height in question is the removal of a black pine (Pinus nigra), specimen number 02-0226 to be specific.

We have been monitoring this particular tree for several reasons and over many years, as part of our tree safety management programme.

The tree is within zone one, which is an area with a high ‘target value’, such as places with high public use, paths and rides, adjacent to buildings, visitor centres, car parks, or as in this case near a public road.

The decision to remove any tree is one that is never taken lightly, and an assessment of risk is always based on the following:

  • The identification of hazards that pose a significant risk – defects or factors that could result in failure and have the potential to cause harm
  • Quantifying the risk associated with the hazards identified should be estimated by considering the following factors:
    • The probability of tree failure depending on the severity of the hazards identified;
    • The likely consequence of tree failure, which will depend largely on the dimensions of the overall tree or the particular limbs identified as hazards;
    • The occupancy of the site or level of use – proximity and business of paths etc.

This is an old black pine that has graced the Old Arboretum opposite the school gates since it was planted by the Holford family.

However, it is now in poor condition with some physical defects:

  • It has a major lean and over-hangs a main road;
  • There are early signs of root plate instability;
  • It is multi-stemmed and has been supported with cable bracing in the past which requires frequent inspection.

Due to this combination of factors, we have judged that it has now reached the end of the line and needs to be removed.

We are fortunate enough to have a highly skilled team of arborists at Westonbirt who are undertaking this tree work in a safe and efficient manner.

On a positive note and as always, this very same team will look to plant a young specimen when the ground settles here in due course.

Mark Ballard, Curator

STIHL Treetop Walkway: an update

Tuesday, January 26th, 2016

I’m really excited to see that the timber decking is now in place along the entire length of the walkway! It’s a fantastic milestone to reach, and means we can now move on to the final stages of construction, including the handrail and interpretation.

the start of the walkway from the Welcome Building end
This is the start of the walkway from the Welcome Building end. The new entrance sign is in place and the first part of the interpretation is in position showing the diameter of the largest tree by volume, General Sherman (a giant sequoia (Sequoiadendron giganteum) tree located in California, USA), and the names of all the donors who have funded Phase Two of the Westonbirt Project. The top of the timber bench which will be placed in this area should also arrive this week.

one of the views from the walkway at almost the highest point
This is one of the views from the walkway at almost the highest point at the edge of Silk Wood.

the view looking along the walkway
This photo shows the view looking along the walkway. You can just about see the access to the rope bridge and walk-around feature. You will be right in the canopy at this point with several yew trees, oaks and sycamores either side of the walkway.

the walk-around feature
This is the walk-around feature which will eventually include a swinging rope bridge and a separate platform with several “totems” representing the different layers of a tree.

timber boards
The rope bridge’s handrail and side mesh is in; the next task will be to install the timber boards so visitors can walk across to the platform, and the installation of the platform deck and handrail.

a real sense of the curves is only fully apparent when stood on the walkway itself
Despite seeing the walkway on several plans, 3D models and from the ground a real sense of the curves is only fully apparent when stood on the walkway itself. This photo is taken as you cross Willesley Drive, with the crow’s nest feature on the right.

The staircase up to the crow’s nest
The staircase up to the crow’s nest is steep and has been designed with a bounce! As you can see in the picture this staircase takes you up to a black pine. Don’t worry the staircase isn’t finished! The contractors will be installing timber stair treads and will fit a poem to the stair once complete. Once at the top of the stairs you can peer through telescopes so you can become a nature detective.

Large boulders
Some of you may have noticed some large stone boulders. We have placed these around the bases of some of the walkway legs to protect the walkway from vehicles. The contractors will be installing the last of the boulders next week to protect the legs alongside Willesley Drive.

solid larch handrail
On top of the steel balustrade the contractors will install a solid larch handrail; it is bespoke, chunky and is rarely straight! Some of the interpretation fits to the handrail, including a game at the end of the walkway, so we need it to be in place before the interpretation designers arrive to install it.

Although the walkway looks as if it’s ready to walk on, there are a few more elements to install before we can open. No one is more eager to finish the walkway than I am, having been involved in the project for the last six years. But I think you will agree once you’ve experienced the walkway that it will be well worth the wait!

Sophie Nash, Project Manager

STIHL Treetop Walkway: An Update

Wednesday, January 13th, 2016

Work is continuing on the STIHL Treetop Walkway, which will give visitors an exciting new perspective on trees. The walkway is part of phase two of the Westonbirt Project.

Now that the main structure of the Walkway is finished the contractors have moved on to the finishing touches before work begins on the interpretation.

The Scottish larch for the decking has arrived!

Scottish larch decking

Each piece of timber deck has a grip strip to reduce the chance of slipping in the wet or in icy conditions. The timber is thicker than normal decking to ensure it has a longer lifespan, although the timber has also been treated.

Thick timeber decking with grip strips

The contractors have started at the Silk Wood end of the Walkway and are making great progress. Each piece has been pre-cut to ensure the exposed timber has been treated but to also reduce waste.

Decking in place on the walkwayDecking in place on the walkway

Work will soon begin on the installation of the handrail, benches and the interpretation.

Sophie Nash, Project Manager

Tree of the month: January 2016

Tuesday, January 12th, 2016

Oriental planeWhat is tree of the month?
Platanus orientalis (oriental plane)

Why is it tree of the month?
A parent of the often seen London plane, Platanus x hispanica (the other being Platanus occidentalis), the oriental plane is attractive in leaf and equally so without, with its patchwork bark exposed and fruit dangling from the branches. Attaining large proportions, it has more of a weeping habit than the hybrid and plants will layer, given the opportunity. In cultivation since the sixteenth century, it is native to southeastern Europe and western Asia.

Where can I find it?
Significant specimens can be found in the Old Arboretum on Mitchell Drive and Main Drive. Another characterful example can be found in Silk Wood on Willesley Drive close to the junction with Green Lane. Younger plants are also dotted around the collection, including known wild origin specimens from Cyprus, Lebanon and Turkey.

Dan Crowley, Dendrologist