RVT Case 2 Poplar

Now I would like to show you something from the other end of the size spectrum, a very large Poplar and this one is a bit more involved than usual because this is a tree that is managed by a group of residents in common space within a farm redevelopment.

I have been formally assessing this tree for about five years for the residents and in fact this is the second Reduction Via Thinning that we have applied to this tree. 

So as this is a large tree I assessed the tree from the ground and prepared some perspective images showing where I thought the individual leading branches should be pruned back to.

The images were used at the beginning of the job to discuss with the climber and groundsman, the route that the climber would take through the tree so that he visited each segment just once removing what was needed to be removed as he passed through that part of the canopy. Sometimes you have to retrace your steps, but not often.

This is a big tree and it stands within communal space on this gated development so it’s the residents who are at risk if it were to fall, so it is to their credit that they thought enough of this landmark tree to ascribe the resources to have it formally assessed periodically and then size managed to reduce the likelihood of major failure.

The test came at my last inspection early in 2011. That revealed that the wound at the base of the tree concealed a large cavity affecting the middle of the tree. OK the thickness of the sound timber around the cavity was such that I had confidence that the tree was strong enough and then we had already nudged the odds by applying a light 10-15% RVT some five years previously, but still, in these circumstances, the odds needed to be nudged further in the residents favour.

I responded by suggesting a further 15% RVT but some residents were not convinced. They actually wanted the tree reducing in height and by a significant amount.

At that point in time I was still putting the finishing touches to this book so I could not present it and suggest they absorbed it to see if it changed their perceptions but what I did do was suggest that this tree would form part of the book, if they followed my advice.

That advice had not really changed since my first report and broadly speaking it was that this was a large tree in a windswept location, with a defect at its base. Now as then, it had good leaf density and good leaf colour, so it was and is in good physiological health. So the original light RVT was suggested to alleviate structural stresses and start the process by which we would encourage the tree to develop the lower canopy.

Eventually, over three passes in 20 years, the overall height would be reduced while preserving the functionality and vitality of the tree so that the overall size reduction be done while preserving and developing a natural looking lower canopy.

We arrived at a compromise which was a heavy RVT of 25% so I prepared the proposed pruning images that showed red lines to indicate where the final cuts needed to be made.

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Of course, I was assuming that no major changes are needed once the climber can see the branches close up.

Then I prepared the modified images showing what the tree would probably look like after the job had been completed and presented these proposal images to the residents for their collective approval.

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OK, not the best CGI but such images show a client what they can expect and provide a clear comparison against which to judge the work of the Arborist and groundsman.

Above is an image showing the tree once the RVT of 25% was completed. You will see that the climber made some adjustments to the proposed cuts but overall the effect is as expected. A reduced but still natural looking tree that is unlikely to loose large sections in high winds.

Such predictive images are always going to be subject to changes but it is interesting to see just how predictable RVT actually is.

On the next 2 pages are the images of the tree once the works were completed so that you can judge just how close to the proposed shape, we managed to achieve.

I think that you should be able to see how the lower canopy is thickening and taking over from the high canopy as the high canopy is subjected to simulated wind pruning.

This job took a day for a 3 man team to complete.

This is the tree back in 2006 before we started to apply a light RVT. It had extended side branches and I suspect that a lot of roots had been removed a few years earlier to create the driveway. So the tree was large, had a defect at its base and had lost roots.

Obviously the full natural and flowing canopy is best, but I think RVT comes ca close second to doing nothing at all. Doing nothing was not an option here.

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