In article ,
Kay wrote:
In article , John H Wood
writes
Can anyone explain why ring barking a tree will usually eventually
kill it, but cutting the stem either at head height as in pollarding
or at ground level as in coppicing will merely produce shoots from
where the cut was made.

The food from the roots travels up the tree in a thin zone just inside
the bark, so ring barking will prevent food getting to anywhere above
the ring. Water travels up much deeper in, so the death is quite slow
since the tree is still getting water to all parts.

Food obviously can still get to anywhere below the ring or the cut, so
those trees which throw new shoots readily (and not all do) will produce
new shoots from below the cut.

Yes, precisely.

One other aspect that is important is that many trees throw new shoots
readily when young, but not when old - and, as Rackham points out,
coppicing effectively resets the clock. This is a major reason why
mature oaks (and many other trees) do not regrow from their stumps
after being cut down, but can be coppiced over hundreds of years.


Regards,
Nick Maclaren.