Failure of Roots

lenphillips · 1st January 2008, 04:40 PM

Online Seminars has an article called Failure of Roots. It will be available for discussion at the website for January and February.
on-line-seminars.com - Failure of Roots

According to the research most trees fail from bad soil. I have to disagree. In my experience the bulk of failures in my city are caused by root failure. What is your experience on this topic?

Ekka · 1st January 2008, 09:14 PM

Len, The article mentioned 2/3's of failures are due to poor soil, soil fracturing.

Most wind blown trees tend to heave soil within a 2.5m radius of the trunk regardless of tree size.

Looking over some of Mattheck's work he talked about soil shear too.

Seems when the soil turns to a bog and the tree blows over that it's called a soil failure not root failure. However all blow overs have to break roots at the soil fracture line unless of course it's a small tree.

I mainly see root failures, not too often do I get a 4m high wall of soil like I see in many USA and Euro pics of tree failures. Then again, the soils are much shallower here perhaps putting more emphasis onto roots to hold.

I liked the article and it had some good general rule of thumbs here.

Quote:

Thresholds have been determined for root decay and severance.

* Major buttress roots are considered significantly decayed if the thickness of sound wood on the root is less than the tree diameter (DBH) times 0.15. So, on a tree 30 inches (57.5 cm) dbh, each major root must have at least 4? inches (11 cm) of solid wood. If it has less, it is considered severely decayed.
* Major buttress roots that were cut within a distance of three times the trunk diameter are considered high risk.
* If more than a third of the major buttress roots are missing or decayed, the tree should be considered a high risk
* If more than half of the major buttress roots are missing or decayed, the tree should be considered a critical risk.
* Thresholds should be reduced in cases of the tree exposure considerations indicated above, plus weak-wooded species, decayed roots that are opposite the lean (the tension-loaded roots), when the live crown ratio is less than 33%, or other risk factors when the tree owner is willing to accept only a slight risk.

ropensaddle · 1st January 2008, 09:45 PM

Quote:

Originally Posted by Ekka

Len, The article mentioned 2/3's of failures are due to poor soil, soil fracturing.

Most wind blown trees tend to heave soil within a 2.5m radius of the trunk regardless of tree size.

Looking over some of Mattheck's work he talked about soil shear too.

Seems when the soil turns to a bog and the tree blows over that it's called a soil failure not root failure. However all blow overs have to break roots at the soil fracture line unless of course it's a small tree.

I mainly see root failures, not too often do I get a 4m high wall of soil like I see in many USA and Euro pics of tree failures. Then again, the soils are much shallower here perhaps putting more emphasis onto roots to hold.

I liked the article and it had some good general rule of thumbs here.

Interesting bogs would also promote root rot on trees not adapted to
wetlands. Most of the trees failing around here I would relate to saturated
soil conditions combined with supercell thunderstorms!

Ekka · 1st January 2008, 10:00 PM

So those failures are called soil failures or root failures?

ropensaddle · 1st January 2008, 10:08 PM

Quote:

Originally Posted by Ekka

So those failures are called soil failures or root failures?

Thats a tough one Ekka, I would feel that each is the answer
soil conditions,root structure and high winds.

Ekka · 1st January 2008, 10:10 PM

Well, I think if the article reckons 2/3's are soil failures then that's the reason.

Would it have failed if the soil wasn't saturated? Probably no. Maybe that's how we need to look at it.

ropensaddle · 1st January 2008, 10:15 PM

Quote:

Originally Posted by Ekka

Well, I think if the article reckons 2/3's are soil failures then that's the reason.

Would it have failed if the soil wasn't saturated? Probably no. Maybe that's how we need to look at it.

Exactly high winds have some consideration too,the clearcut cut
the year before, contributed to high winds hitting this tree in a way
the tree had not had time to respond etc. It is a bigger picture than
summing it up.

Ekka · 2nd January 2008, 12:13 AM

Yeah, I'm wondering how the guys who collect the statistics classify it I suppose.

But all factors to remain except the rain (which means no soil saturation) .... would it have failed? Tough question.

We have had a few dry years, plenty of windy days with little rain and some decent failures ... that'd be roots as very little soil went over. Like Azrael's spotted gum failure, my grey gum failure and even the New Farm Park Jacaranda failure.

azrael · 2nd January 2008, 02:10 AM

I thought the article gave a good overview.
There are SO many factors which combine in the throw equation ... If there is a high degree of predictability/probability then it the appropriate decisions can be made.
If a tree does not have a sufficiently sized, symmetric root-plate then it's a much easier call...for an urban environment (Coder as reference).

The problems arise from the unknown...with unknown history...where evidence of previous construction damage is unseen or disguised .... or where the signs of root-decay are obscured or are missed...and the tree indeed is compromised in the structual root-plate. Be observant...especially if there is aerial decline...(an Arborist friend says "like a forensic pathologist")

Sometimes good advice goes unheeded too ... One is memorable ... exercising my duty-of-care responsibilities. The case: A leaning tree (early-mature), on a 45o sloping bank on the footpath reserve (no footpath) in a suburban area overhanging roadway. I noticed several holes/voids appearing in the bank around the roots... 1m from the base of the tree Reported same to Council (in writing) for their attention and action ...this is 3 years ago...the tree is still there...but one day.....

For me...I'll still be an ambulance chaser....checking out local tree failure reports...nothing like first hand knowledge.

TrevMcRev · 2nd January 2008, 02:50 AM

This one left a 12 person spa sized hole full of water in the ground.
24hrs solid rain followed by wind back in Feb 04 i think...
Definate waterlogged soil but had to break roots to tip over. Bit murky though, i didnt bring my shorts that day anyway.

That was an insurance job which i lost by being up front with the quote instead of just doing it like we were first instructed to. I wanted to clarify what happens with the stump/rootball. They said get rid of it, the debris and reinstate the hole.

The cheaper quote they then got ground it and left an 8m3 pile of grindings!

azrael · 2nd January 2008, 12:53 PM

Was that a Pinus radiata???...Great pics anyway

That root-plate looks about 3-3.5 x the trunk radius.

Ekka · 2nd January 2008, 01:52 PM

Great pics Trev, I haven't been to one of them type of windthrows for a few years now.

Again the radius of where the soil lifted is around that 2.5m from the trunk region.

It most likely is where roots are somewhat thinner and perhaps less concentrated, easier breaking point. Closer would be harder and further maybe not strong enough to heave the soil. Just seems so common.

When I was in the Lamington National Park there were some huge brushbox windthrows, I mean these are old old trees maybe 2mDBH and 200' tall with perhaps 5mdia where the flare and buttresses meet the ground. Even on huge trees like that the soil severence was no more than 3m away.

Here's the grey gum failure I had, notice bugger all soil went with the tree, I've been getting mostly this type of failure for the last few years.

Ekka · 4th February 2008, 10:32 PM

From this thread a soil failure

Storm uprooted Euc

mdvaden · 12th February 2008, 03:43 PM

Hard question to answer sometimes.

On Portland's west side in Beaverton, we were standing outside during one storm watching the tall Douglas firs down the street.

One would fall, then another, then another, over several blocks.

A few roots broke, but the main issue was that the soil became too saturated.

But what the trees had in common, was they were remnants of a forest logged and removed to build the homes. So really, the trees blew over due to a tree care failure.

As far as our own property some years back where I grew up, none of our 12 large douglas firs blew over or broke. And they endured the 1962 or 1963 Columbus Day storm which brought winds over 100 mph to the Portland area.

Those trees had grown out in the open, and were not irrigated. Just whatever nature provided.

1st January 2008, 04:40 PM	#1 (permalink)
lenphillips Gettin' motoring Join Date: Nov 2007 Location: Massachusetts Posts: 43	Failure of Roots Online Seminars has an article called Failure of Roots. It will be available for discussion at the website for January and February. on-line-seminars.com - Failure of Roots According to the research most trees fail from bad soil. I have to disagree. In my experience the bulk of failures in my city are caused by root failure. What is your experience on this topic? __________________ Len Phillips Administrator Online Seminars for Municipal Arborists

1st January 2008, 10:00 PM	#4 (permalink)
Ekka Eric Frei Administrator - Brisbane L5 (Dip) Hort Cert III Arb + some Join Date: Jan 2007 Location: Brisbane Posts: 5,673	Re: Failure of Roots So those failures are called soil failures or root failures? __________________ Remember to use the "search" function, if you have answers/questions post them so everyone can benefit. Free Tree and Green Industry Link Directory Qualified Brisbane Tree Lopping Brisbane Tree Care, Consultations and Arborist Reports Forum Sponsors

1st January 2008, 10:10 PM	#6 (permalink)
Ekka Eric Frei Administrator - Brisbane L5 (Dip) Hort Cert III Arb + some Join Date: Jan 2007 Location: Brisbane Posts: 5,673	Re: Failure of Roots Well, I think if the article reckons 2/3's are soil failures then that's the reason. Would it have failed if the soil wasn't saturated? Probably no. Maybe that's how we need to look at it. __________________ Remember to use the "search" function, if you have answers/questions post them so everyone can benefit. Free Tree and Green Industry Link Directory Qualified Brisbane Tree Lopping Brisbane Tree Care, Consultations and Arborist Reports Forum Sponsors

2nd January 2008, 12:13 AM	#8 (permalink)
Ekka Eric Frei Administrator - Brisbane L5 (Dip) Hort Cert III Arb + some Join Date: Jan 2007 Location: Brisbane Posts: 5,673	Re: Failure of Roots Yeah, I'm wondering how the guys who collect the statistics classify it I suppose. But all factors to remain except the rain (which means no soil saturation) .... would it have failed? Tough question. We have had a few dry years, plenty of windy days with little rain and some decent failures ... that'd be roots as very little soil went over. Like Azrael's spotted gum failure, my grey gum failure and even the New Farm Park Jacaranda failure. __________________ Remember to use the "search" function, if you have answers/questions post them so everyone can benefit. Free Tree and Green Industry Link Directory Qualified Brisbane Tree Lopping Brisbane Tree Care, Consultations and Arborist Reports Forum Sponsors

2nd January 2008, 02:10 AM	#9 (permalink)
azrael Afterburner is shakin' Join Date: Dec 2007 Location: Earth Australia Posts: 340	Re: Failure of Roots I thought the article gave a good overview. There are SO many factors which combine in the throw equation ... If there is a high degree of predictability/probability then it the appropriate decisions can be made. If a tree does not have a sufficiently sized, symmetric root-plate then it's a much easier call...for an urban environment (Coder as reference). The problems arise from the unknown...with unknown history...where evidence of previous construction damage is unseen or disguised .... or where the signs of root-decay are obscured or are missed...and the tree indeed is compromised in the structual root-plate. Be observant...especially if there is aerial decline...(an Arborist friend says "like a forensic pathologist") Sometimes good advice goes unheeded too ... One is memorable ... exercising my duty-of-care responsibilities. The case: A leaning tree (early-mature), on a 45o sloping bank on the footpath reserve (no footpath) in a suburban area overhanging roadway. I noticed several holes/voids appearing in the bank around the roots... 1m from the base of the tree Reported same to Council (in writing) for their attention and action ...this is 3 years ago...the tree is still there...but one day..... For me...I'll still be an ambulance chaser....checking out local tree failure reports...nothing like first hand knowledge.

2nd January 2008, 12:53 PM	#11 (permalink)
azrael Afterburner is shakin' Join Date: Dec 2007 Location: Earth Australia Posts: 340	Re: Failure of Roots Was that a Pinus radiata???...Great pics anyway That root-plate looks about 3-3.5 x the trunk radius.

2nd January 2008, 01:52 PM	#12 (permalink)
Ekka Eric Frei Administrator - Brisbane L5 (Dip) Hort Cert III Arb + some Join Date: Jan 2007 Location: Brisbane Posts: 5,673	Re: Failure of Roots Great pics Trev, I haven't been to one of them type of windthrows for a few years now. Again the radius of where the soil lifted is around that 2.5m from the trunk region. It most likely is where roots are somewhat thinner and perhaps less concentrated, easier breaking point. Closer would be harder and further maybe not strong enough to heave the soil. Just seems so common. When I was in the Lamington National Park there were some huge brushbox windthrows, I mean these are old old trees maybe 2mDBH and 200' tall with perhaps 5mdia where the flare and buttresses meet the ground. Even on huge trees like that the soil severence was no more than 3m away. Here's the grey gum failure I had, notice bugger all soil went with the tree, I've been getting mostly this type of failure for the last few years. __________________ Remember to use the "search" function, if you have answers/questions post them so everyone can benefit. Free Tree and Green Industry Link Directory Qualified Brisbane Tree Lopping Brisbane Tree Care, Consultations and Arborist Reports Forum Sponsors

12th February 2008, 03:43 PM	#14 (permalink)
mdvaden Astronaut Join Date: Feb 2007 Location: Oregon Posts: 578	Re: Failure of Roots Hard question to answer sometimes. On Portland's west side in Beaverton, we were standing outside during one storm watching the tall Douglas firs down the street. One would fall, then another, then another, over several blocks. A few roots broke, but the main issue was that the soil became too saturated. But what the trees had in common, was they were remnants of a forest logged and removed to build the homes. So really, the trees blew over due to a tree care failure. As far as our own property some years back where I grew up, none of our 12 large douglas firs blew over or broke. And they endured the 1962 or 1963 Columbus Day storm which brought winds over 100 mph to the Portland area. Those trees had grown out in the open, and were not irrigated. Just whatever nature provided. __________________ ____________________________________ Grove of Redwood TITANS Oregon BIGOOT trap

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