Oak Removal - I need your help
- Thread starter opposablethumb
- Start date
- Location
- Federal Way WA
http://www.treeworks.co.uk/downloads/2%20-%20JK_Static%20Integrated%20031203.pdf
Sean,
Basically, 100% means the tree will remain standing at Gale Force 12 on the Beaufort scale, or about 75 mph winds. Very old large girthed trees are often extremely sound despite the decay that is present. Yes there are other parts of the tree that may be structurally suspect, but there again we often assume decay=weak. Statics Integrated Assessment takes into account the trees geometry, load, and material properties. Engineers know this as the triangle of statics. Cylinders are very strong, and the greater the diameter of a cylinder, the thinner the material needs to be. So 581% based on a trunk that is solid, means that there is a lot of room for hollowness yet still remaining strong enough.
So, we prune old trees only enough to bring them back into a range of adequate safety factor. The more fragile the tree, the lesser dose of pruning. If there are super high value targets, the dose may go up.
Robert's oak tree would also be a good tree to examine with the TRACE methodology. Based on the photos and site description, I would probably end up rating it a 9 or 10 out of the total possible 12. Puts it solidly in the monitor annually/mitigate risk area of the 12 point TRACE scale, and that makes sense, too.
Sean,
Basically, 100% means the tree will remain standing at Gale Force 12 on the Beaufort scale, or about 75 mph winds. Very old large girthed trees are often extremely sound despite the decay that is present. Yes there are other parts of the tree that may be structurally suspect, but there again we often assume decay=weak. Statics Integrated Assessment takes into account the trees geometry, load, and material properties. Engineers know this as the triangle of statics. Cylinders are very strong, and the greater the diameter of a cylinder, the thinner the material needs to be. So 581% based on a trunk that is solid, means that there is a lot of room for hollowness yet still remaining strong enough.
So, we prune old trees only enough to bring them back into a range of adequate safety factor. The more fragile the tree, the lesser dose of pruning. If there are super high value targets, the dose may go up.
Robert's oak tree would also be a good tree to examine with the TRACE methodology. Based on the photos and site description, I would probably end up rating it a 9 or 10 out of the total possible 12. Puts it solidly in the monitor annually/mitigate risk area of the 12 point TRACE scale, and that makes sense, too.
opposablethumb
New member
- Location
- Mid-Atlantic
Cool that this thread has stayed alive...
Zale - will do.
Zeb - Thanks for elaborating more. I need to read those pdfs - tomorrow lunch break. Here's the deal though. The trunk, i.e. the cylinder, may be really strong, as you describe. Shoot, it's withstood the mountaintop weather up till now 20 or 30 years after having its roots nuked by the construction of the parking lot. But that's precisely what's worrisome - the roots. Those buttress roots all have decay. I can reach my hand back in the hollows and touch the crumbling wood (brown rot?). How far does that decay reach into the support roots that are underground? How long can we responsibly leave it there, hanging its crown over 18-22 year olds parking their cars? The trunk may be solid for years and years and years to come, but if that root plate deteriorates, as it is doing, then the tree is going to fail - right? We've had a handful of oaks - whites and reds - our our wood lines (not edge trees) that have failed at the root crown due to structurally compromised, decayed buttress roots. With this tree, decayed roots seem like the big unknown and the drive towards removal...
Zale - will do.
Zeb - Thanks for elaborating more. I need to read those pdfs - tomorrow lunch break. Here's the deal though. The trunk, i.e. the cylinder, may be really strong, as you describe. Shoot, it's withstood the mountaintop weather up till now 20 or 30 years after having its roots nuked by the construction of the parking lot. But that's precisely what's worrisome - the roots. Those buttress roots all have decay. I can reach my hand back in the hollows and touch the crumbling wood (brown rot?). How far does that decay reach into the support roots that are underground? How long can we responsibly leave it there, hanging its crown over 18-22 year olds parking their cars? The trunk may be solid for years and years and years to come, but if that root plate deteriorates, as it is doing, then the tree is going to fail - right? We've had a handful of oaks - whites and reds - our our wood lines (not edge trees) that have failed at the root crown due to structurally compromised, decayed buttress roots. With this tree, decayed roots seem like the big unknown and the drive towards removal...
- Location
- Federal Way WA
Well.... You could have Phillip Van Wassenaer come down form Toronto to perform a static pulling test and you'll have an exact safety factor for both trunk failure and root failure. Elasto-inclino pulling test, or you could put a throw line high in the canopy and gently, might I repeat gently, pull on the tree to create an oscillation. Think fly fishing here, pull and release, pull and release. When you have some good movement you can visually observe if there is movement in the root plate. Its good to have a helper for this. We call this a dynamic pulling test. Not to be confused with the static pulling test, which Phillip can do for you; it has a complete set of data complied from inclinometers and elastometers with a known tonnage and a lot of math. The dynamic is a simple way to get a visual indicator as to whether or not the tree is shifting in the soil, or if there are weak points in the pedestal, trunk or scaffold branches. You should be doing something like this before you climb an old tree anyway. Its pretty handy tool to add to your assessment tool kit.
- Location
- Hawaii
[ QUOTE ]
However, how many trees are brought down because of fears about litigation instead of scientific understanding? Kind of a sad thought.
[/ QUOTE ]
I'd say a lot. Watching Philip et al. in Ohio last summer pull testing trees to failure was an eye opener; the forces the trees could withstand (especially those trees with significant cavities/wounds) were incredible. Some of the trees even bent all the way to the ground like a rubber band.
Another important point mentioned was that a lot of these trees that have been pulled to failure during this test and others in the field, didn't break at the places you would expect. This is also true in the real world where cavities are definitely not the defining criteria for where the actual failure would occur or if it would occur at all.
jp
However, how many trees are brought down because of fears about litigation instead of scientific understanding? Kind of a sad thought.
[/ QUOTE ]
I'd say a lot. Watching Philip et al. in Ohio last summer pull testing trees to failure was an eye opener; the forces the trees could withstand (especially those trees with significant cavities/wounds) were incredible. Some of the trees even bent all the way to the ground like a rubber band.
Another important point mentioned was that a lot of these trees that have been pulled to failure during this test and others in the field, didn't break at the places you would expect. This is also true in the real world where cavities are definitely not the defining criteria for where the actual failure would occur or if it would occur at all.
jp
guymayor
Branched out member
- Location
- East US, Earth
"How far does that decay reach into the support roots that are underground?"
That's what I asked you to measure weeks ago, job 1. trowel and yardstick. seems even tree guys don't like getting their hands and knees dirty. (rolleyes)
"How long can we responsibly leave it there, hanging its crown over 18-22 year olds parking their cars?
do job 1 first then you will have a clue about how much of the crown to leave hanging.
"The trunk may be solid for years and years and years to come, but if that root plate deteriorates, as it is doing,
how do you know it is advancing? The rot may have stalled, and new growth compensating. until you do job 1...
"then the tree is going to fail - right?
potentially, but you can do a lot to mitigate that risk potential. measure the weakness and the strength, for starters.
" decayed roots seem like the big unknown and the drive towards removal.
well on the next tree, don't expose a hole for your boss to overreact to, until you are ready to make decay a Known, and assess tree risk in a comprehensive and competent way.
and don't listen to sawdust-lusting goobers like riggs who see 2 holes = firewood. jk glenn
That's what I asked you to measure weeks ago, job 1. trowel and yardstick. seems even tree guys don't like getting their hands and knees dirty. (rolleyes)
"How long can we responsibly leave it there, hanging its crown over 18-22 year olds parking their cars?
do job 1 first then you will have a clue about how much of the crown to leave hanging.
"The trunk may be solid for years and years and years to come, but if that root plate deteriorates, as it is doing,
how do you know it is advancing? The rot may have stalled, and new growth compensating. until you do job 1...
"then the tree is going to fail - right?
potentially, but you can do a lot to mitigate that risk potential. measure the weakness and the strength, for starters.
" decayed roots seem like the big unknown and the drive towards removal.
well on the next tree, don't expose a hole for your boss to overreact to, until you are ready to make decay a Known, and assess tree risk in a comprehensive and competent way.
and don't listen to sawdust-lusting goobers like riggs who see 2 holes = firewood. jk glenn
opposablethumb
New member
- Location
- Mid-Atlantic
Thanks Guy. I am very appreciative of the time you're taking to reply to my questions - you are educating me for free! I've got to return the favor somehow...
"Do job 1". Thought I had, but I clearly didn't. Lesson learned for the next tree where we'll need to assess the risk for failure.
"comprehensive" and "competent" will be my two main goals.
"Do job 1". Thought I had, but I clearly didn't. Lesson learned for the next tree where we'll need to assess the risk for failure.
"comprehensive" and "competent" will be my two main goals.
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