A Mature Elm With a Big Lean

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MarkGraham
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A Mature Elm With a Big Lean

Post by MarkGraham » Mon Feb 22, 2016 6:34 pm

There are many parkway trees planted in Oak Park, IL including some still persisting American elms.

Here is a photo of what I believe is a grouping of these elms. Note the tree with the big lean (it leans to the East). It leans so much, about 40 degrees from vertical, that its canopy is actually on the other side of the street from its base.

Note the other trees around it are relatively straight. This is the most pronounced leaning tree I have run across in this area. What could have caused this lean? The tree has persisted at this angle of lean for at least ten years. Maybe the soil was loose around the base when the tree was planted or maybe this is something genetic? Also how long would such as tree be expected to stand?

Mark
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Don
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Re: A Mature Elm With a Big Lean

Post by Don » Mon Feb 22, 2016 7:23 pm

Mark-
Most trees will show signs of adjusting to changing conditions. It would appear that the leaning elm has been growing at that angle from the start...how is it said, "As the twig is bent, so is the tree inclined"?
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Rand
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Re: A Mature Elm With a Big Lean

Post by Rand » Tue Feb 23, 2016 10:45 am

Don,

I disagree with your assessment. I think the ground failed under the tree and it partially uprooted with it was ~ 3/4 of its current size, because the root flair looks pitched at a funny angle and there are the same number of branches on the 'uplean' and 'downlean' sides of the trunk-trees down grow branches away from the light. Also, if you look closely, you can see some subtle discontinuities in the growth of the branches coming off the up-lean side of the trunk.

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Will Blozan
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Re: A Mature Elm With a Big Lean

Post by Will Blozan » Tue Feb 23, 2016 11:04 am

Rand,

Could have been planted under a large tree that made it "forage" for light across the open street, then when that was removed it sent reiterated trunks onto the gap above...

Just my first thought.

-Will

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Rand
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Re: A Mature Elm With a Big Lean

Post by Rand » Tue Feb 23, 2016 12:41 pm

Will Blozan wrote:Rand,

Could have been planted under a large tree that made it "forage" for light across the open street, then when that was removed it sent reiterated trunks onto the gap above...

Just my first thought.

-Will
That doesn't look likely to me in this case because the branches coming off the trunk at more or less equal angles on the uplean & downlean sides of the trunk. Also, all the trees that I've noticed doing this almost always curve and snake a bit as they reach for the light gap. This tree really looks too straight for that. Rather it looks like a normal tree abruptly pushed over ~ 35˚, and then the branches on the uplean side abruptly strarted growing straight up toward the light.

Click to zoom in to look at the discontinuities I referred to previously:
Leaning-Elm-anno.jpg

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Don
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Re: A Mature Elm With a Big Lean

Post by Don » Tue Feb 23, 2016 2:00 pm

Rand/Will-
It would be interesting to know this tree's history from property owner or neighbors!
It's been my experience that trees that have been "abruptly pushed over" will usually have a mound on the 'away' side where the roots have 'given' up a little 'purchase'.
As to the branching, if you rotate the image so that the leaning elm is vertical, the branching on both sides are surprisingly symmetrical (this would support your theory that it had grown straight up, then 'pushed over'.
I don't know...not much buttressing on the 'leaning side'...I'd have expected more, if it had been "growing into the light".
Don Bertolette - President/Moderator, WNTS BBS
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Science Center
Grand Canyon National Park

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ryandallas
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Re: A Mature Elm With a Big Lean

Post by ryandallas » Tue Feb 23, 2016 5:35 pm

Hi, Mark,

It doesn't look like phototropism... And it probably isn't the genotype... So I'd say it's the symptom of... IDK... soil collapse?

That's a really cool tree! I'm surprised it hasn't been taken down.

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Rand
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Re: A Mature Elm With a Big Lean

Post by Rand » Tue Feb 23, 2016 10:58 pm

ryandallas wrote:Hi, Mark,

It doesn't look like phototropism... And it probably isn't the genotype... So I'd say it's the symptom of... IDK... soil collapse?
It's hard to tell, but maybe a storm drainage box in the adjacent curb is collapsing? It's odd how those things are put together. They aren't solid concrete. Rather they are bricks loosely stacked together. I assume this is to allow water from the surrounding soil to percolate in.
That's a really cool tree! I'm surprised it hasn't been taken down.
Yeah, as paranoid as people tend to be about hazard trees, that is surprising.

Joe

Re: A Mature Elm With a Big Lean

Post by Joe » Wed Feb 24, 2016 7:27 am

Will Blozan wrote:Rand,

Could have been planted under a large tree that made it "forage" for light across the open street, then when that was removed it sent reiterated trunks onto the gap above...

Just my first thought.

-Will
I agree with Will. If the tree had moved because of soil failure or any other reason- it would have threatened the road- it would have been obvious that it would have to be removed. But, by growing up under another tree and in the direction of the road (towards the south?)- it could have survived for years, then having been "released" when the overtopping tree was removed- it would then reach for the sky. Of course the question arises- why along that road, would one tree be under the other like that?
Joe

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RayA
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Re: A Mature Elm With a Big Lean

Post by RayA » Wed Feb 24, 2016 8:01 am

I'm certainly no expert on this, but I'd have to agree with Rand... it looks to me like that tree had grown upright then was tipped for some reason, and branches then began to go up to the light. The trunk has a slight curve that suggests to me that it had been vertical and had curved to the right somewhat, toward the road and the light, before it abruptly went over. It also looks like the road has been resurfaced in the recent past (you can see the seam down the middle, and along the left gutter, indicating that new asphalt layers were put down)... that could have covered up road damage if there had been any. If the tree had originally grown at its present angle, I'd expect the trunk to have some curvature in the upward direction, the opposite of the slight curve it has now (like the tree just before it on the left side of the street). My theory could of course be entirely bogus, but I've never made a mistake yet... I thought I had once, but I was wrong. And somehow I know that if I'm right about this, I'll owe Bob an ice cream for asserting the truth; and if I'm wrong, I'll have to buy him an ice cream for being so dumb.

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