Hey! That's my line!
There are many variables. But it would be easy to determine the probability of failure with certain species.
As said before Bradford Pear comes to mind. Silver maple would be one of our indigenous species.
Yeah some of the softer and poorly branched trees are pretty well known but I would like to combine that stuff to include other trees and then combine that with the fungal info found in Schwarze amongst others.
It's not out there but what a project that would be...
It's not out there but what a project that would be...
ATH
Been here much more than a while
- Location
- Findlay, Ohio
You say that as if something is wrong with species bias. That is essential for professional and responsible practice - especially at plant selection time, but even during management.
There are some constants that can at least provide a start of data. For example, what if somebody did the research to create a chart similar to the one for lumber in the USFS publication I linked with green wood. For example, test adequate # of replicate samples of each species. 4" diameter material taken from limbs (or trunks...just so it is the same) x 4' long with no visible defects or knots and bent them until breaking. Measure how much force it took and how far it flexed before breaking.
That doesn't mean that every pear will be weaker than every oak tree...but it will tell us how much weaker it is. How much less bending it can take before failure.
We can also be more intentional about recording data after storms. Just saying more individuals of species XYZ broke than species ABC isn't good enough. Need to have consistently trained individuals look at both broken and unbroken trees and record what is happening and how defects did or didn't impact that. Huge undertaking, but not un-doable.
Isn't this part of what they are trying to accomplish with the Tree Biomechanics workshops in NE Ohio?
Yeah and the International failure database but apparently that came off the rails?
Not just wood strength but also tendencies of where branches, stems, or even entire trees are failing. Combine that with what may or may not have been wrong with that tree to begin with.
I'll admit this would all amount to tendencies but you have to start somewhere.
Imagine Dirr x Mattheck x Schwarze in one resource.
Not just wood strength but also tendencies of where branches, stems, or even entire trees are failing. Combine that with what may or may not have been wrong with that tree to begin with.
I'll admit this would all amount to tendencies but you have to start somewhere.
Imagine Dirr x Mattheck x Schwarze in one resource.
ATH
Been here much more than a while
- Location
- Findlay, Ohio
You at OTCC Jason? "No relationship between greenwood strength and ice storm susceptibility" - Dr. Kim Coder, UGA
ATH
Been here much more than a while
- Location
- Findlay, Ohio
...but species is a major factor in likelihood of ice damage.
Perhaps to @guymayor 's point, abiotic stressors are almost always more operative than biotic ones. Subjectively, local wind events (during Irma, during summer monsoons, etc.) are far more predictive of failure than tree species. But, I am convinced that tree species is a predictor (albeit mild compared to other factors). I just think it would be more pragmatic to take a model averaging approach with multiple models (e.g. wind exposure, soil moisture, tree community root structure, disturbance, tree species, etc.), each having an evidence ratio to compare it's usefulness relative to the other models.
ATH
Been here much more than a while
- Location
- Findlay, Ohio
Yeah...Dr. Coder said he attributes 80% of failure probability to "load".
Should make an interesting flow chart.
guymayor
Branched out member
- Location
- East US, Earth
As usual, he's about right. Wood is central to forestry but not arboriculture.
Redtree
Participating member
- Location
- Mt. Albert
I have a few insights that may be relevant to this great discussion.
1. I think Guy is concerned with species bias because it could affect species selection (as mentioned) or it could deem a species less valuable, or worthless, due to one characteristic. Should we stop planting Bradford Pear or Silver Maple because they fail a lot? As noted earlier, purple cars aren't safer, there is just less of them. Of course Silver maples in Toronto are seen as dangerous. (and often are 'dangerous') There are lots of big old ones that live there. (and they could have been managed much better, and have been more successful and plentiful) And of course they should STAY on the planting list, because they are successful, large, and generally long lived, especially in the urban setting, adding more to the canopy per unit than most or possibly any other. With the goal of diversity we also need species that fail more often. And yes a species profile would be helpful to create more appropriate structural pruning prescriptions. The problem is, it could also cause a sort of species discrimination, so we just need to emphasize the details and the goals of this kind of profiling.
2. If different species have different breaking strengths per diameter, then how might that affect the pruning regiment and dosage? does it matter? maybe. If a species breaks to certain diameters more often, then how might that affect the target diameters for structural/reduction pruning? does it matter? probably. If a species breaks more often than others (per capita) then should it be a better candidate for reduction? yes. primarily in an urban setting. not just to reduce risk to targets but to increase the durability and longevity of the canopy.
3. one of the best things to do is to observe storm damage of all kinds in your local area. even if you have to travel to it. take pictures. keep in mind the damaged trees vs the population to avoid overly faulting the common species or not noticing the uncommon. note that just because poplars and walnuts held up in the ice, they may not in the wind. and j
although Siberian Elm and Birch fail in the ice, they may not fail as much in the wind. upper limbs fail in ice more often perhaps not because they are weaker but more likely because the ice is thicker there. also upright limbs need to bend 180 degrees when ice loaded, in order to rest parallel with gravity. reaching limbs only need to bend 90. limbs on a 45 degree to begin with might have mixed results(as they all do to some degree of course). ( I was amazed with this pattern in 2013 ice in Toronto). what's the angle at which an upright limb becomes a reaching limb? there is more than just upright and horizontal. when reducing a multistem madness tree, all should be reduced. addressing a dominant or ratio may or may not come later.
4. Even if you were to determine a pattern of failure for each species, what would this do? possibly some help for newer arborists or unfamiliar species. I suppose that's a good thing. But still there are so many factors that you need to consider. if the targets are highly valuable and very close, then you may go heavy even on a decent Norway Maple with no decay (several cuts up to 3" max) but if the target is less valuable and further away you might go fairly light on a Weeping Willow (several cuts up to 3" max) notice heavy on a Norway is the same as light on a Weeping Willow, assuming they are both 50 - 60 feet tall. another variable. the point is that there can't be a standard maximum cut for a 60 foot silver maple. what if there is significant decay AND recently removed adjacent ash? 4"-6" max cuts? Or no decay but multiple stems with twists (no cable opportunity) and narrow crotches? 2"-3" max.? or less if it's a 6 stemmed instead of 3 stemmed?
the point is, as I think a wise man once said already. the formulas and math can never work at least to prescribe work, due to too many variables. and what else matters to this than prescribing work? Guy, I thought you held that opinion about the math?
but the patterns can be identified and described. the trends and tendencies are important.
we are so focused with risk that we risk losing diversity and canopy by not planting a species or by removing a risk tree instead of mitigation pruning. our nature is to destruct and produce instead of progress.
I think species profiling is a good idea but needs good details to avoid derails.
I also think that the outcome of profiling should result in reduction cut diameter limits. Not a range necessarily, but a limit. a lower limit to the range is unnecessary. 'cuts up to 2 inches' or 'lengths up to 12 feet removed from crown periphery'. the point is that with thorough reduction you should have many cuts of many lengths made almost entirely in the periphery. And in most trees that really need it, the entire periphery, often including the top, should extend less.
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1. I think Guy is concerned with species bias because it could affect species selection (as mentioned) or it could deem a species less valuable, or worthless, due to one characteristic. Should we stop planting Bradford Pear or Silver Maple because they fail a lot? As noted earlier, purple cars aren't safer, there is just less of them. Of course Silver maples in Toronto are seen as dangerous. (and often are 'dangerous') There are lots of big old ones that live there. (and they could have been managed much better, and have been more successful and plentiful) And of course they should STAY on the planting list, because they are successful, large, and generally long lived, especially in the urban setting, adding more to the canopy per unit than most or possibly any other. With the goal of diversity we also need species that fail more often. And yes a species profile would be helpful to create more appropriate structural pruning prescriptions. The problem is, it could also cause a sort of species discrimination, so we just need to emphasize the details and the goals of this kind of profiling.
2. If different species have different breaking strengths per diameter, then how might that affect the pruning regiment and dosage? does it matter? maybe. If a species breaks to certain diameters more often, then how might that affect the target diameters for structural/reduction pruning? does it matter? probably. If a species breaks more often than others (per capita) then should it be a better candidate for reduction? yes. primarily in an urban setting. not just to reduce risk to targets but to increase the durability and longevity of the canopy.
3. one of the best things to do is to observe storm damage of all kinds in your local area. even if you have to travel to it. take pictures. keep in mind the damaged trees vs the population to avoid overly faulting the common species or not noticing the uncommon. note that just because poplars and walnuts held up in the ice, they may not in the wind. and j
although Siberian Elm and Birch fail in the ice, they may not fail as much in the wind. upper limbs fail in ice more often perhaps not because they are weaker but more likely because the ice is thicker there. also upright limbs need to bend 180 degrees when ice loaded, in order to rest parallel with gravity. reaching limbs only need to bend 90. limbs on a 45 degree to begin with might have mixed results(as they all do to some degree of course). ( I was amazed with this pattern in 2013 ice in Toronto). what's the angle at which an upright limb becomes a reaching limb? there is more than just upright and horizontal. when reducing a multistem madness tree, all should be reduced. addressing a dominant or ratio may or may not come later.
4. Even if you were to determine a pattern of failure for each species, what would this do? possibly some help for newer arborists or unfamiliar species. I suppose that's a good thing. But still there are so many factors that you need to consider. if the targets are highly valuable and very close, then you may go heavy even on a decent Norway Maple with no decay (several cuts up to 3" max) but if the target is less valuable and further away you might go fairly light on a Weeping Willow (several cuts up to 3" max) notice heavy on a Norway is the same as light on a Weeping Willow, assuming they are both 50 - 60 feet tall. another variable. the point is that there can't be a standard maximum cut for a 60 foot silver maple. what if there is significant decay AND recently removed adjacent ash? 4"-6" max cuts? Or no decay but multiple stems with twists (no cable opportunity) and narrow crotches? 2"-3" max.? or less if it's a 6 stemmed instead of 3 stemmed?
the point is, as I think a wise man once said already. the formulas and math can never work at least to prescribe work, due to too many variables. and what else matters to this than prescribing work? Guy, I thought you held that opinion about the math?
but the patterns can be identified and described. the trends and tendencies are important.
we are so focused with risk that we risk losing diversity and canopy by not planting a species or by removing a risk tree instead of mitigation pruning. our nature is to destruct and produce instead of progress.
I think species profiling is a good idea but needs good details to avoid derails.
I also think that the outcome of profiling should result in reduction cut diameter limits. Not a range necessarily, but a limit. a lower limit to the range is unnecessary. 'cuts up to 2 inches' or 'lengths up to 12 feet removed from crown periphery'. the point is that with thorough reduction you should have many cuts of many lengths made almost entirely in the periphery. And in most trees that really need it, the entire periphery, often including the top, should extend less.
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guymayor
Branched out member
- Location
- East US, Earth
Ryan, I largely agree with all that. Our experience with species is limited, but it has a place. Will less experienced arborists and others relying on such lists instead of getting info from the tree via inspection? That is my main concern.
I'm not anti-math, just highly skeptical on using formulas (as many others are). See page 12 here; full of assumptions and generalisations, unexplained and perhaps inexplicable. All respect to the author, but it smells like smoke and looks like mirrors. http://www.historictreecare.com/wp-content/uploads/2015/02/Eiche_Ohio-131204.pdf
I like your spec ranges with max cut sizes and lengths; always adjustable based on communications between climber and manager.
I'm not anti-math, just highly skeptical on using formulas (as many others are). See page 12 here; full of assumptions and generalisations, unexplained and perhaps inexplicable. All respect to the author, but it smells like smoke and looks like mirrors. http://www.historictreecare.com/wp-content/uploads/2015/02/Eiche_Ohio-131204.pdf
I like your spec ranges with max cut sizes and lengths; always adjustable based on communications between climber and manager.
Redtree
Participating member
- Location
- Mt. Albert
yes I see your point. species profiling should not mean a similar reduction application for each individual tree of that species. But it could explain trends, or species tendencies to look for. Such as the common problem of Norway Maple and unbalanced tip growth vigour. very often Norway's have vigorously growing codoms and dwarfed central stems. This kind of occurrence needs regular attention and an overdose reduction to the codom could result in more added stress than necessary.
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Redtree
Participating member
- Location
- Mt. Albert
I also suspect that in Frank Rinns proposed reduction for that oak would result in far more than 65 percent wind load reduction. more like 80. But yes both numbers are a guess. the thing is with the proposed reduction which I see as an overdose, would leave the crown way below the higher wind velocities. remember the higher you get the windier it is. This is compounded by the surrounding buildings and canopy
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treehumper
Carpal tunnel level member
- Location
- Ridgefield, NJ
How would one account for past arboricultural practices and their impact on failure dynamics? In collecting species specific data what would the parameters be in selecting the specimens within the study group? Looking at urban trees in Toronto, especially the street or park trees, what do you know of the history of the work done on the trees and the impact it has on the particular species?
Maybe it would entail starting at a cellular level and working out from there. In so much as, the baseline would be the fundamental biomechanical strength with influencing factors layered on top in order to bolster or mitigate the end analysis of a given tree. In that way, one would be starting with factors that are consistent within a given species and then accounting for external factors that affect the final performance characteristics.
Maybe it would entail starting at a cellular level and working out from there. In so much as, the baseline would be the fundamental biomechanical strength with influencing factors layered on top in order to bolster or mitigate the end analysis of a given tree. In that way, one would be starting with factors that are consistent within a given species and then accounting for external factors that affect the final performance characteristics.
