How many people realise Claus Mattheck has been proven wrong about root excavation.

Don Ross

Professor Gruber in two 2007 papers has proven that Professor Claus Mattheck was wrong about hollow trees and about root excavation to check for tree overturning.

What percentage of Australian arborists consider Mattheck right about the hollowness of trees?

Professor Lothar Wessolly knows that a tree wall thickness to radius ratio of 10% is okay based upon 4,500 lateral load tests only on problem trees in Germany

Mattheck says the ratio should be 32% even for steel tubes in his BLOT book.

I have designed over 1,000 steel piles with a wall thickness of 2% (Lucinda, Dalrymple Bay & Abbot Point Jetty structures.)

Issue is becoming important because BCC arborists have water and air blasted roots of more than 100 jacaranda trees in New Farm Park needlessly and for some trees most unsafely. Of the 15 jacarandas cut down by BCC in the last year at least 8/15 would have been saved if BCC knew how to do a lateral load test.

Ciao Don Ross

Eric Frei

There certainly has to be a better way than current practices.

The industry (unlike engineering) doesn't have known proven standards. There's no 100% sure and definitive knowledge of overturning or stability strengths. Much of what happens is opinion generated.

Look at New Farm park, they spent $90k diagnosing trees, trimmed some heavily, picus, air blast, ground radar etc and still fell down on a relatively still day.

A 30% wall thickness for all species of trees? Big different comparing ironbark to poplar. But the fallen trees at New Farm didn't have cavities, it wasn't about how hollow, it was a bout root strength and brittle timber.

There's a lot of work to be done in this area I feel. From the soils trees are anchored in to their size and shape.

We have a thread running on New Farm park, and I ask for proposals here about how to address aging trees and their issues.

Currently we base our decisions on experience, some data and the consequences of failure. Where the target is deemed too valuable then that influences the decision a lot.

A good starting point is flushing out some of the myths.

__________________

treeseer

Here is the Gruber article and another.

oops i am still chasing down the gruber piece; i agree it did a good job of pulling us away from hard-and-fast criteria for condemnation.

Attached Files

Risk Bond over r debunk.pdf (148.9 KB, 340 views)

Sean Freeman

Don it is right and proper that you raise this issue, it is one that we have discussed in a number of threads including the one on New Farm Park Jacs. We have discussed many aspects of what some of us percieve as the critical problems relating to the more recent management of issues there.

I have not spoken directly to Claus Mattheck on this topic but have spoken to number of people who have triedd to discuss the problems that are evident in his calculations and the conclusions he draws all laid out very clearly in the docs we have linked in the forum.

Now specifically as to whether the lateral load test would have meant the retention of some of the Jacs removed...well I'm not so sure BCC, have ended up trying to square a circle when it comes to satisfying somewhat contradictory perspectives in relation to the trees at New Farm...again something we have pulled apart quite a bit in the thread.

When managing large older (previously mismanaged from a THC perspective) parks, the bar is set far higher in relation to acceptable risk of harm to the public. Indeed sometimes the bar is set so illogically high you could justify the removal of all objects completely if they had to meet the requirements of risk mitigation that the trees are expected to.

My own feeling on this is that being open and inclusive is the key...no secret squirrel...make public the problems, canvass the local residents, engage the best specialists available, encourage public envovlement in the process.

Its very easy for me on the outside to sling mud, so thats not what I'm doing...I do know some of the BCC officers envolved at the edges in trying to deal with the problems in the park, the individuals I know are trying to get the best outcome for the park and the people who use it....however they are working within a bureaucratic structure that determines what they can and can't do, that is the reality of very large organisations.

In the case of the Jacs that I have looked at closely at New Farm, both failed and not...These are trees that have been buried over the last 30/40yrs to a depth of over 1m in some places along the ring road, kerb and channel replacement has severely impacted the adventitous root systems that the trees produced on the road side, compaction and grass maintenance activities have seriously reduced the functionality of any roots present in the upper soil profiles on the opposite side of the trees.

I did not see the root excavations undertaken on behalf of BCC, so can't comment, would agree that care in how you treat the critical root zone is a massive concern in the case of damaged trees.

I am something of a fan of the lateral load test, however just like any test, picus, resio, drill, hammer, RCX, it is how you interpret the results and incorporate those results into your assessment and diagnosis and within that what the acceptable criteria are that is important.

newguy18

Never heard of him until now but the question and other posts bring up some intresting thoughts and theories.In mst parks in the us where they plant trees they place mulch around the tree from trunk to drip line.The theory being it helps keep weeds down which would prevent string trimmer damage and it also help protect the uppermost roots close to the trunk.I'm sure most places world wide do the same.

__________________
Have your say join us today.


old schooler

Sean Freeman

Yep you would have thought so eh?

newguy18

okay are you saying it doesn't work?I'm only asking because chances are you have a lot more knowledge than me.

__________________
Have your say join us today.


old schooler

Sean Freeman

No you're right it works just fine (sorry to be confusing!) what I meant was you'd think/expect that tree owners....LGA's would take that very simple and cheap option to protect the long term health of their tree assets....they don't by and large.

Robert STAVROU

G'day people,
Mathecks' t/r ratio has also been questioned, in Professor F. Schwarze new book (goggle ENSPEC), apparrently C. Matheck has purchased some of his published research material from other scientists (common practice, those that have the funds buy the info from those that are struggling). The downside is that you may not get the chance to doublecheck the finer details.

regards STAV

__________________
STAV

treeseer

here is the gruber piece. thanks for the tip re schwarze book; is there a title or isbn #?

Attached Files

t over r debunk Gruber_Arb Jl_2008 Vol 31.pdf (1.04 MB, 500 views)

Sean Freeman

Diagnosis and Prognosis of the Development of wood decay in Urban trees.

Here's a good paper from Peter Sterken on the same topic of t/R ratios

1780233.pdf

Eric Frei

Yes, a lot of people also forget the Mattheck 50:1 slenderness ratio.

So beside the T/R ratio there's also the 50:1 to consider.

You might have a 0.10ratio hollow tree but it might be like the Stanley Park Hollow tree and be only 4x DBH in height making it pretty safe.

Certainly a complex equation, but I think if a core sample were extracted and tested then you'd know definitively what is there and it's strength, then with models like Sterken's surely engineers would know the strength of the tree. However what about soil and roots?

That's the tough question, we have talked about soil failures and roots failures, not all trees snap off at the stem, most uproot as is the case in New Farm Park. Then we say oh it was soil failure or root failure. Either way they're parts of the tree we dont see.

What about these pull tests, what if soil conditions change? Like dry vs wet bog? What about the failure point not being linear on a graph but parabolic, in other words with a 2 tonne load it bends 2 degrees, 4 tonne is not 4 degrees but 6 degrees and 6 tonne is failure but you only test to 2 tonne so how would you know when real failure will occur? Like we seen one tree fall in light breeze after lots of weight and sail removed, things change and obviously the test or any test is obsolete the day after as those conditions have changed.

I think that the pull tests have merit but am not completely sold. Look at any fracture graph in engineering and you'll not see a straight line but a curved one.

__________________

treeseer

You indeed are a prince among men. thanks for the sterken link. A toast to you sir.

however i googled that title of schwarze's and got nothing new jsut fungal stategies.

Sean Freeman

Guy there are copyright issues with some of the included works from other sources (as told by Francis to ISAAC workshop this year) not a real drama but enough to delay publication...assuming that ENDSPEC have bought copies in advance? or something....Basically noone can get a copy yet.

treeseer

i'
ll just check with springer the publisher

Don Ross

Now there are 17 jacarandas cut down in the Park & near the Park.

BCC may have found one with phellinus noxius as well.

See the two photographs attached.

Falsehoods about brown root rot in jacaranda trees in New Farm Park could be the fuse to blow the lid of arboricultural world's worst practice in New Farm Park.

Ciao

Don Ross

Attached Thumbnails

 

Attached Files

cropped### Acting unethically by Editor F and Leader S g leads to environmental bad practi (218.7 KB, 131 views)

Hamadryad

Once again i see people struggling to see the logic and thinking behind matthecks principals.

Am I right In thinking those of this forum have an issue both with TR ratios and slendernes ratio criteria within the VTA method devised by the great Prof Dr claus mattheck?

Am I to assume that these park jakarandas where condemmned on the basis of VTA assesments?

glennak

Hamadryad the roots on your tree avitar are what the general public think they are really like. Pictures like this are the cause of a lot of tree deaths like the tree in the colgate add. How often have you heard "I only cut the surface roots".

Hamadryad

I know nothing of the colgate add tree, I am simply concerned that there are people who take a negative stance against VTA method devised by Claus.

I dont wish to set up an argumentative situation, but to understand why and to try and resolve some of the mis understandings that seem to have been made through mis interpretation of the method.

Eric Frei

What have you got to say or offer? We've had ours if you read it all.

__________________