Poinciana Prop Job - Thoughts?

Eric Frei · 19th August 2011, 12:53 PM

What do you think of this poinciana propping technique?

It is in the infamous New Farm Park (I will also copy this post to the New Farm Park thread).

My thoughts are, what's with the clamping down over the top of branches, perhaps stop the branch/tree lifting up and prevent sideways style rotational forces? Often low long laterals do get twisted and then break.

What about the little bits of CCA treated board in there to fill the gap? Obviously they do not want 'slop' so the branch gets flapped around and they want to be able to accommodate future expansion, bit of a maintenance thing checking up though, and introduction to a damp spot where timber is in contact with the tree's bark. Maybe it's this whole aversion thing to drilling the tree (called invasive by some).

Eric Frei · 19th August 2011, 01:46 PM

When trees are cabled etc we often get a choice of dynamic or static. The argument being that movement generates a response from the tree, some call it reaction wood and others call it Thigmomorphogenesis.

I have uploaded a PDF about Thigmomorphogenesis.

Now why is it that all prop jobs are static?

Why is it the very same principals used to argue about static vs dynamic cabling is not used for propping?

Back in 2008 in a tree report I wrote (contrary to some orgs BS about needing 5 years post graduate experience to know what I am on about):-

Quote:

For the tree to remain it's impossible to
install a ground cable for support due to
the road, however there is space on the
other side to install a prop. Propping trees
has been done for decades and not really
utilized much here in Australia, however
some Jacaranda's in New Farm Park have
now been propped. A suitably engineered
prop would have to have minimum 2
posts of support and be positioned above
the center of gravity of the tree so that
even if the entire root system were to fail
the tree couldn't pivot and topple from
being top heavy.
Caution must be used as to allowing the
tree room for growth and movement.
Trees move in the wind and a solid prop
could create a whiplash effect and have
limbs/trunk etc above the prop point snap
(also known as karate effect). Attachment
of the prop to the tree must allow for
growth and not restrict the outer growth
(cambial growth), stainless steel through
bolting a preferred option with rod
exposed so the tree can grow over it as
per the sketch. The foundation of the prop
to have some shock absorber capacity
with either spring or rubber mounting etc
to allow some movement.

Would not a system like this be far superior, allows movement, doesn't have to be inspected and adjusted etc.

silent 2035 · 19th August 2011, 02:19 PM

Eric,

I get that some aged trees with elongated and over extended primary lateral branches need suppport BUT to this extend rings alarm bells ... what about liability and longevity? It would appear they stripped the mulch layer, dug post footings to secure the Delonix to ground with countless metal objects. Fabrication and pin style props appear great but agree the volume would surely effect the natural branch movement.

Why not just fence the subject tree to restrict congregation beneath the tree canopy and improve the subject tree ability to survive? Or was this a measure of QTRA?

Eric Frei · 19th August 2011, 05:00 PM

This tree was fenced in the past. So they propped it and removed the fence.

I wonder is the root crown decayed or something that it requires anchoring to the ground? BCC would have had it checked, picus most likely, means Enspec most likely.

I wonder if BCC would tell us without an RTI?

I'm going to email them. I should have got a tree number or something, damn it. I'll just ask for information about the 6 prop Delonix regia and refer them to this thread.

Eric Frei · 19th August 2011, 05:10 PM

I just emailed them, they have 20 days to respond.

Jeff Darby · 19th August 2011, 05:11 PM

The paper you uploaded on Thigmomorphogenesis (touchresponce) is a good read. It will it interesting to see if BCC respond to your email request.

Victor Lindsay · 19th August 2011, 09:19 PM

How hard would it be to put some type of shock absorber in that system...like on automobiles? Hey, did i just invent something?

Jeff Darby · 20th August 2011, 07:35 AM

There's allways a reason behind setting up such major structural support system. However you have to ask why is the system so rigid, why did they not go the full mile and engineer movement ability to the these supports? that allow support and movement at the same time ? Like the other two members have also questioned.

So we are going to have a mature tree held up by steel supports then they just walk away with out addressing the trees biological needs...

come on aireate the ground out to the drip line, fertilise with and appropriate fertilizer then re apply properly aged mulch from the same species. Then this tree will have a walking stick and the shot in the arm it deserves..

silent 2035 · 20th August 2011, 08:11 AM

Eric,

The person who might know about the works is Brent Dowden from Brisbane Council.

Propping

Allowing some form of movement I agree is interesting ..... depicting the actual location and desired volume of tree movement would have to be the key and agree a device that allows movement could be worth exploring ........

Years ago we used static prop arrangement on a hinge based which allowed continual adjustment against the branch region in an attempt to minipulate supporting timber, plus provide branch support BUT found we were not deligent enough to follow through plus I believe the age of the Cypress macrocarpa was against us.

In view of the subject tree props and volume of props, only the very apical region has movement and therefore poses many challanges in the near future given the tree age I believe. I guess if they wanted to secure the subject tree to the ground they have achieved this BUT what an eye saw and surely fencing would have reduced the risk ... and aided in tree preservation.

Looking at this tree under wind loading would be interesting.

Was it ?Enspec who propped tha tree? possible they used their own wind loading devices to determine the actual prop location?

Eric Frei · 20th August 2011, 09:26 AM

In this picture we are looking at the lowest longest lateral branch which grows south.

We can see numerous previous pruning cuts which may have helped cause the lions tailed affect.

I prune a lot of poincianas and always try to cut from the ends back toward the trunk pushing it back in size, shorter and more compact.

I believe part of the reason why these trees (poincianas) have failed down there, both in part or whole is because they were fenced and left to grow into over extended abominations.

I wrote about that in this thread.

Quote:

Originally Posted by Eric Frei

The included bark unions at the saddle are a weak point. Often as poincianas age the shear weight of their own limbs can cause failure at the saddle. Often unpruned trees in ideal environments experience this as they have in New Farm Park. Two recently failed in New Farm Park, these were the fenced off trees in ideal conditions, this post and this post. Weight reduction pruning and reduction pruning would considerably reduce the probability of failure. Poincianas left to their own means unpruned will often grow until they droop to the ground, then they grow upwards again and so on. It's plausible that mankind comes along and crown lifts them so their canopy doesn't touch the ground which could be part of the problem as the trees own "prop" is being eliminated.

I have no problem at all saying that this tree pruned properly would have easily another 20 years reliable life left in it, if not more. It is a hypocrisy to cut this tree down, a farce, and could even be a collaboration of contractors and BCC to make a dollar or some other hidden agenda, writing reports to appease a motive is nothing new, I present this and this.

To use OHS etc as an excuse to remove this tree simply doesn't fly, and certainly is inconsistent with BCC's typical approach on VPO trees for home-owners.

I smell something corrupt here. I haven't even got into cabling, props, rods etc to extend this trees life, there's ample opportunity for this tree to remain.

Eric Frei · 8th September 2011, 08:04 AM

I received this response from BCC yesterday.

Quote:

Dear Mr Frei

Thank you for your email of 19 August 2011 concerning the large Poinciana tree in New Farm Park that has six metal props supporting it.

In answer to your questions:

1) The tree has been propped to mitigate the risk of branch failure due to the age, form and inherent issues associated with these factors.

2) The propping system is not a rigid system and allows the trees branches to move as required and react accordingly in the tension and compression regions of the branch. There are only floating footings present not rigid ones.

3) The props are suitably engineered and certified, supplied and installed by Enspec Environment and Risk. Any questions about the props can be directed to Managing Director, Craig Hallam on 0417 027 152

4) The fence was removed based on the installation of the propping system.

If I can be of any further assistance with this issue please call me on 3403 8888.

Regards

Brent Dowden
Arboricultural Outcome Coordinator
Asset Services
Field Services
Brisbane Infrastructure

I am having trouble with number 2, I didn't inspect the bases that well but I doubt they are floating or move, so I will go and have another look this weekend.

I think the "floating" system is more likely based on movement within the cuffs (yes they look like handcuffs) on pieces of wood in there.

Jeff Darby · 8th September 2011, 06:45 PM

It must be time for my eye sight test because I can not see any type of dampening system at the base of these supports ? Sooooo point number two is biggest typo i've seen or it an outright lie ? imo. What say you Mr Dowden ?

For a system of support to float, it has to be able to move and give support while doing so, with the packing in place theres no movement at all. The pictures above shows me a system of support only.

Eric Frei · 8th September 2011, 08:46 PM

Here's a picture of the base plate.

It measures 1m x 1m

From what I can make out the base plates sit flat upon a section of ground that most likely has been compacted beneath it.

I think but am yet to confirm that a rectangular hole was dug, perhaps 1m2 and 300mm deep, compacted dead flat and the plate sits on it.

But that terminology of calling it a floating footing comes from engineer speak.

A floating slab alone does not suggest movement, after all house slabs are "floating slabs" most of the time as they are poured on top of the soil but suggesting that allows horizontal movement in this case is absurd. Sure house slabs do perhaps go up and down on clay soils depending on moisture content but here we are discussing tree branches that move sideways also.

So now an argument could break out that they can move, but I doubt it as I tried. I got the lowest branch further out from the prop and tried to sway it horizontally, no chance.

So what is it that will allow movement at the base?

Well, only when force exerted exceeds skin friction of said plate will it move, and skin friction will rise depending on weight exerted downward on the surface of the plate.

Maybe that explains why they handcuff over the top of the branch, maybe the concept is that the branch is locked to the support and the support should "shimmy" a little.

Maybe from soil tests they didn't want to use screw piers etc and set into a soil more stable or volatile for that matter whilst the tree sits still. Imagine the tree upon the soil goes up and down whilst the prop which is into more stable soil sits still? Could you end up with a gap between the prop and the tree or perhaps the opposite?

I wonder what this cost tax payers and I wonder what the concept is behind it? I feel another RTI coming on to get the truth not what people want to feed me.

I conclude it is a rigid system that is cumbersome to maintain, who is going to be stuffing around with that packing?

Darrell Mcleod · 8th September 2011, 09:30 PM

Wouldn’t you think they would have used nuts and bolts that could not be tampered with and what about the packing?

Quote:

Originally Posted by Brent Dowden

2) The propping system is not a rigid system and allows the trees branches to move as required and react accordingly in the tension and compression regions of the branch. There are only floating footings present not rigid ones.

3) The props are suitably engineered and certified, supplied and installed by Enspec Environment and Risk. Any questions about the props can be directed to Managing Director, Craig Hallam on 0417 027 152

2) above – is this exactly correct?

Perhaps an explanation and understanding could be gained from Mr Hallam together with the reasoning behind this ‘system’

And are there better systems out there to deal with a tree like this?

19th August 2011, 12:53 PM	#1
Eric Frei Admin - Owner Palm & Tree Services in Brisbane Join Date: Jan 2007 Location: Brisbane Posts: 12,994	Poinciana Prop Job - Thoughts? What do you think of this poinciana propping technique? It is in the infamous New Farm Park (I will also copy this post to the New Farm Park thread). My thoughts are, what's with the clamping down over the top of branches, perhaps stop the branch/tree lifting up and prevent sideways style rotational forces? Often low long laterals do get twisted and then break. What about the little bits of CCA treated board in there to fill the gap? Obviously they do not want 'slop' so the branch gets flapped around and they want to be able to accommodate future expansion, bit of a maintenance thing checking up though, and introduction to a damp spot where timber is in contact with the tree's bark. Maybe it's this whole aversion thing to drilling the tree (called invasive by some). Attached Thumbnails __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Palm and Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

19th August 2011, 02:19 PM	#3
silent 2035 Sappling Join Date: Aug 2011 Location: Australia Posts: 10	Re: Poinciana Prop Job - Thoughts? Eric, I get that some aged trees with elongated and over extended primary lateral branches need suppport BUT to this extend rings alarm bells ... what about liability and longevity? It would appear they stripped the mulch layer, dug post footings to secure the Delonix to ground with countless metal objects. Fabrication and pin style props appear great but agree the volume would surely effect the natural branch movement. Why not just fence the subject tree to restrict congregation beneath the tree canopy and improve the subject tree ability to survive? Or was this a measure of QTRA?

19th August 2011, 05:00 PM	#4
Eric Frei Admin - Owner Palm & Tree Services in Brisbane Join Date: Jan 2007 Location: Brisbane Posts: 12,994	Re: Poinciana Prop Job - Thoughts? This tree was fenced in the past. So they propped it and removed the fence. I wonder is the root crown decayed or something that it requires anchoring to the ground? BCC would have had it checked, picus most likely, means Enspec most likely. I wonder if BCC would tell us without an RTI? I'm going to email them. I should have got a tree number or something, damn it. I'll just ask for information about the 6 prop Delonix regia and refer them to this thread. __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Palm and Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

19th August 2011, 05:10 PM	#5
Eric Frei Admin - Owner Palm & Tree Services in Brisbane Join Date: Jan 2007 Location: Brisbane Posts: 12,994	Re: Poinciana Prop Job - Thoughts? I just emailed them, they have 20 days to respond. __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Palm and Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

19th August 2011, 05:11 PM	#6
Jeff Darby Moderator - Previously known as JayD Join Date: Feb 2007 Location: TreeWorld, Sydney Australia Posts: 2,059	Re: Poinciana Prop Job - Thoughts? The paper you uploaded on Thigmomorphogenesis (touchresponce) is a good read. It will it interesting to see if BCC respond to your email request. __________________ Member: Australian Tree Association Join the Australian Tree Association...Have your voice heard ! Arboriculture, A life long study for some, a passing phase for others © Jeffrey J Darby 2011

19th August 2011, 09:19 PM	#7
Victor Lindsay Mature tree Join Date: Aug 2007 Location: ? Posts: 441	Re: Poinciana Prop Job - Thoughts? How hard would it be to put some type of shock absorber in that system...like on automobiles? Hey, did i just invent something?

20th August 2011, 07:35 AM	#8
Jeff Darby Moderator - Previously known as JayD Join Date: Feb 2007 Location: TreeWorld, Sydney Australia Posts: 2,059	Re: Poinciana Prop Job - Thoughts? There's allways a reason behind setting up such major structural support system. However you have to ask why is the system so rigid, why did they not go the full mile and engineer movement ability to the these supports? that allow support and movement at the same time ? Like the other two members have also questioned. So we are going to have a mature tree held up by steel supports then they just walk away with out addressing the trees biological needs... come on aireate the ground out to the drip line, fertilise with and appropriate fertilizer then re apply properly aged mulch from the same species. Then this tree will have a walking stick and the shot in the arm it deserves.. __________________ Member: Australian Tree Association Join the Australian Tree Association...Have your voice heard ! Arboriculture, A life long study for some, a passing phase for others © Jeffrey J Darby 2011 Last edited by Jeff Darby; 20th August 2011 at 07:40 AM.

20th August 2011, 08:11 AM	#9
silent 2035 Sappling Join Date: Aug 2011 Location: Australia Posts: 10	Re: Poinciana Prop Job - Thoughts? Eric, The person who might know about the works is Brent Dowden from Brisbane Council. Propping Allowing some form of movement I agree is interesting ..... depicting the actual location and desired volume of tree movement would have to be the key and agree a device that allows movement could be worth exploring ........ Years ago we used static prop arrangement on a hinge based which allowed continual adjustment against the branch region in an attempt to minipulate supporting timber, plus provide branch support BUT found we were not deligent enough to follow through plus I believe the age of the Cypress macrocarpa was against us. In view of the subject tree props and volume of props, only the very apical region has movement and therefore poses many challanges in the near future given the tree age I believe. I guess if they wanted to secure the subject tree to the ground they have achieved this BUT what an eye saw and surely fencing would have reduced the risk ... and aided in tree preservation. Looking at this tree under wind loading would be interesting. Was it ?Enspec who propped tha tree? possible they used their own wind loading devices to determine the actual prop location?

8th September 2011, 06:45 PM	#12
Jeff Darby Moderator - Previously known as JayD Join Date: Feb 2007 Location: TreeWorld, Sydney Australia Posts: 2,059	Re: Poinciana Prop Job - Thoughts? It must be time for my eye sight test because I can not see any type of dampening system at the base of these supports ? Sooooo point number two is biggest typo i've seen or it an outright lie ? imo. What say you Mr Dowden ? For a system of support to float, it has to be able to move and give support while doing so, with the packing in place theres no movement at all. The pictures above shows me a system of support only. __________________ Member: Australian Tree Association Join the Australian Tree Association...Have your voice heard ! Arboriculture, A life long study for some, a passing phase for others © Jeffrey J Darby 2011 Last edited by Jeff Darby; 8th September 2011 at 06:49 PM.

8th September 2011, 08:46 PM	#13
Eric Frei Admin - Owner Palm & Tree Services in Brisbane Join Date: Jan 2007 Location: Brisbane Posts: 12,994	Re: Poinciana Prop Job - Thoughts? Here's a picture of the base plate. It measures 1m x 1m From what I can make out the base plates sit flat upon a section of ground that most likely has been compacted beneath it. I think but am yet to confirm that a rectangular hole was dug, perhaps 1m2 and 300mm deep, compacted dead flat and the plate sits on it. But that terminology of calling it a floating footing comes from engineer speak. A floating slab alone does not suggest movement, after all house slabs are "floating slabs" most of the time as they are poured on top of the soil but suggesting that allows horizontal movement in this case is absurd. Sure house slabs do perhaps go up and down on clay soils depending on moisture content but here we are discussing tree branches that move sideways also. So now an argument could break out that they can move, but I doubt it as I tried. I got the lowest branch further out from the prop and tried to sway it horizontally, no chance. So what is it that will allow movement at the base? Well, only when force exerted exceeds skin friction of said plate will it move, and skin friction will rise depending on weight exerted downward on the surface of the plate. Maybe that explains why they handcuff over the top of the branch, maybe the concept is that the branch is locked to the support and the support should "shimmy" a little. Maybe from soil tests they didn't want to use screw piers etc and set into a soil more stable or volatile for that matter whilst the tree sits still. Imagine the tree upon the soil goes up and down whilst the prop which is into more stable soil sits still? Could you end up with a gap between the prop and the tree or perhaps the opposite? I wonder what this cost tax payers and I wonder what the concept is behind it? I feel another RTI coming on to get the truth not what people want to feed me. I conclude it is a rigid system that is cumbersome to maintain, who is going to be stuffing around with that packing? Attached Thumbnails __________________ Protect your rights to work - Join Australian Tree Association My businesses:- Qualified Brisbane Palm and Tree Lopping \| Stump Grinding Brisbane \| Brisbane - Gold Coast Consulting Arborist

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