UKTC Archive

RE: the penny dropped.....

Subject: RE: the penny dropped.....
From: Mark
Date: Jan 04 2019 16:07:57
I've seen a number of old churchyard yews that are growing on a cluster of 
'legs'. Some of the 'legs' are remnants of the original outer edge of the 
trunk and the remainder are internal roots that reached down through the 
decaying centre into the ground and appear to have morphed back into trunks.

Mark

-----Original Message-----
From: uktc-request@xxxxxx.tree-care.info <uktc-request@xxxxxx.tree-care.info> 
On Behalf Of Jim Quaife
Sent: 04 January 2019 16:02
To: UK Tree Care <uktc@xxxxxx.tree-care.info>
Subject: RE: the penny dropped.....

Root ring counts are notoriously unreliable because as they don't need to 
support their own weight against gravity and only need to expand in diameter 
when past the root plate to accommodate increased vascular flow, they don't 
have annual growth rings as such.
When internal (cannibalistic?!) roots occur, the wood into which they grew 
initially has usually decayed away making it look like they grew into an 
airspace.  Logically, they develop into a closed environment which has 
superficial similarities to soil.
The biological process that morphs woody tissue into roots is a mystery (to 
me anyway).
I too have never encountered this in print.
It probably requires a few pints to get to the bottom of it.
Jim

-----Original Message-----
From: uktc-request@xxxxxx.tree-care.info 
[mailto:uktc-request@xxxxxx.tree-care.info] On Behalf Of Jon Heuch
Sent: 04 January 2019 15:41
To: UK Tree Care
Subject: the penny dropped.....

I've been looking through various references on veteran trees to see if the 
adventitious root systems internal to the main stem that we sometimes see in 
hollow old trees (hornbeam, yew, other species?) has a special term..but can 
hardly see any mention of them.

 

Anyway every time I've seen them I've wondered how they developed and what 
process allowed roots to develop above ground and survive whilst they grew to 
the soil surface below ...and why I couldn't find any half grown roots.

 

I am sure others must have seen evidence as shown in the attached photo i.e.
the internal root developing in decaying heartwood but it was a first for me, 
and a clear explanation for my observations. [the photo is upside down so 
rotate thru 180 degrees]

 

1.      We would not expect to see half grown roots as they have developed
within the decaying heartwood, at a time when the decaying wood is soft 
enough to allow root penetration and provide both nutrients, water & air i.e. 
a suitable rooting environment. The root has to reach ground level before all 
the decaying heartwood has gone.
2.      Once the tree is hollow the roots are less likely to form and grow.
3.      I assume, some types of decay may favour root development over
others (cubical brown rot over wet brown rot?)

 

Thus if the internal root was cored & rings counted it might provide some 
indication of how long ago the tree had had decaying heartwood. I don't know 
if such roots have growth rings...anyone any idea? Anyone tried to count 
rings on roots?

 

Jon 

 




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The UKTC is supported by Bosky Trees arboricultural consultancy
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