Frozen soils and tree stability

[Gary Prentice]

I've been looking at a lot of failed/uprooted trees in the last few days. Some were foreseeable with decayed root systems, some explainable. due to restricted rooting areas, but a significant number appear simply to be due to wind forces exceeding the soil cohesion around the root plate.

 

Although wind speeds were high, we've had similar or worse over the last twelve months, often when the soil has been waterlogged. Locally, soils are reasonably dry, but the subzero temperatures have caused the moisture in the upper horizons to freeze and I'm wondering if this had been a factor - reducing cohesion?

 

Thoughts or experiences anyone.

[Gary Prentice]

I'll have to have look at the prevailing wind factor. It just puzzled me a bit yesterday, trying to establish in my mind the various reason as to why particular trees had failed - some quite dramatically (two willows on five cars)

[Stere]

Wind was from a different  direction:

 

 

http://www.bbc.co.uk/news/av/uk-wales-43265912/80-boats-damaged-or-sunk-by-storm-at-holyhead-marina

 

They never usually have problem but wind came from "wrong" way

 

 

 

[Khriss]

Oddly - have had a similar one , two leylandii @30yr abt 16m on a fenceline ( concrete posts n chainlink ) drain running next to tree line , one tree pops over, pulling chainlink up . in a sheltered area - no extreme winds . Baffling . No waterlogging / gley soil pan or significant root decay , roots fractured and tore , pulling up post foundations - V Strange ! K

[Gary Prentice]

Lots and lots of cypresses went over, to be expected with their persistent foliage, but quite a few broadleaves.

 

Wind speed must have been significant at times, because I saw a few sound trees whose stems had just snapped.

[Khriss]

At this time I can only put it down to ryhthmic stress on the tree - the frequency of the gusts causing the failure , bit like soldiers marching over a bridge , if they are in step , the bridge can fail . So they break step . K

[Khriss]

I would say that too Edward C - but without throwing wads of cash on an investigation dunno , will print pic n show it to Himself at the Mattheck lecture in June see if he has a clue K

[Gary Prentice]

18 minutes ago, Khriss said:

I would say that too Edward C - but without throwing wads of cash on an investigation dunno , will print pic n show it to Himself at the Mattheck lecture in June see if he has a clue K

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Or you could ask Vesp...

Edited March 4, 2018 by Gary Prentice

[Treeation]

How about frozen water in the woody component of roots and stems possibly increasing the brittleness of structural integrity? 

[Gary Prentice]

Been a good opportunity to work out the causal factors as to one tree failed and the next stayed up. The willows on the previous page had a footpath about a metre to the windward side. The path was a compacted gravel with some fines, only around 150 mm deep, but enough to inhibit root growth. Looking at the stumps today it was possible to see where roots had changed direction on reaching the path, creating a small root extent in that direction. Interesting stuff.