SIA- the tree pulling test/theory

[Rough Hewn]

I bet they didn’t pull very hard with the Greenpeace building being just down the road.

I used to work for greenpeace years ago. Did the trees in their back yard too.
Never met a group more clueless about the environment and trees.

[Khriss]

My experience - Rough , a member sent pics of an 'ancient woodland' under threat , until I pointed out it was a mature Sitka plantation ....*sigh* K

[Rough Hewn]

My experience - Rough , a member sent pics of an 'ancient woodland' under threat , until I pointed out it was a mature Sitka plantation ....*sigh* K

[emoji23][emoji23][emoji23]

[David Humphries]

On 1/16/2018 at 07:24, Darrin Turnbull said:

Are there any notable measurement differences between wet soil and dry .
After two days of heavy rain on the 5 of October 2017 here in Berlin a storm uprooted many trees maybe the wet soil/conditions made things worse.

Hi Darrin

 

The below offered from a onlookers perspective rather than someone who knows.

 

The tests carried out on this particular tree are focused on the data that is being drawn and evident at the time of the specific conditions of the tree and its environment.

 

So if the soil is saturated at that time, that will play a part and vice versa.

 

I understand that 1000's of pull test have been undertaken since the 1980's on a wide range of tree species and I would assume that those would have been in good and poor condition.

 

I get your point regarding saturated soils, as I've also witnessed seemingly sound roots give way and witnessed root plates slip entirely in saturated soils under wind load.

 

 

[David Humphries]

15 hours ago, Paul Barton said:

......Are the values provided by the test compared with some kind of benchmark data - e.g. the 'normal' elasticity of Platanus wood? 

 

The data on tree species values has been gathered by practitioners since the 80's, I understand that every time a tree pull takes place on any species that data is then fed in to the system to add to the bench mark data.

[David Humphries]

20 hours ago, Paul Barton said:

.......I notice that the tree was a multi-stemmed tree but that the cable was attached to one of the stems rather than linked to all of them.  How does the test allow for the flexure of that stem at its junction with the primary trunk?  I would have thought that this junction would flex and therefore dissipate some of the load from the base - or would that only be true of a dynamic test rather than a static load?

 

 

The tree was pulled from two different angles Paul.

 

I don't know (as i didn't stay for the second) if the second pull (which was carried out perpendicular to the first) was placed on a different section of the canopy or if they used the same point.

 

I suspect they would have set up a different point so that they were pulling at the furthest point from the anchor rather than twisting the canopy during the pull. This would then measure the potential tipping point and stem breakage from a different angle.

 

Not to forget that the Meripilus is the main reason for the test on this tree, so failure from the root plate being the focus rather than the stem or parts of the canopy failing.

[David Humphries]

12 hours ago, Khriss said:

Fascination stuff- but am dubious of what is shows , with wind and climate being so varioable plus the actual expense of the test. Would be good to see test  carried out on a ropey old thing with some die back and root compaction , RE 1987 storms and veteran tree survival rates against semi-matures nearby , K

I don't actually know the cost, that's between the Borough of Islington and the Consultant (although I would like to know)

But it's worth considering that this tree has a very high CAVAT value (Capital Asset Value for Amenity Trees) to the borough and the local resident, so the cost would appear to be worth the outlay.

The removal of such a sizable monster would be considerable.

 

https://www.ltoa.org.uk/resources/cavat

 

 

[David Humphries]

2 hours ago, Mark Bolam said:

I bet they didn’t pull very hard with the Greenpeace building being just down the road.

 

Didn't imagine your old eyes would have picked up on that Mr Bolam  

 

I couldn't possibly comment, but there may have been someone keeping a watching brief from afar 

 

 

 

 

[Arctostaphylos uva-ursi]

Interesting discussion.  The pull test is only testing the structural integrity of the tree not the tree soil interface.  As David says the tests were undertaken due to the presence of Meripilus giganteus a root and butt rot fungi.  Further tests could be conducted in dry and wet spells using tree motion sensing to see if their is any significant difference in motion/recovery.

I would hope that something could be done within the rooting area to improve the conditions there David.

 

[David Humphries]

5 hours ago, Arctostaphylos uva-ursi said:

......I would hope that something could be done within the rooting area to improve the conditions there David.

 

I understand the refurbishment of the playground will address the rooting & surface area.