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.

East Devon
England

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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.

The two extremes are probably willow, which re-shoots very easily, and
therefore is often pollarded or cut to ground level, especially if
you're after young shoots for basket work or for their winter colour;
and conifers, which don't like throwing new shoots, so if cut back
either just grow the branches they already have or, if cut right back to
the ground, die.
--
Kay
"Do not insult the crocodile until you have crossed the river"

"John H Wood" wrote in message
...
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.

East Devon
England

Some plants can re-shoot from dormant buds, others can not, and some can to
start with, then lose the ability as the plant ages and dormant buds die
off.
Ring barking will therefore not always prove fatal, although it will nearly
always do for the section above the ring barking!

--
Charlie, gardening in Cornwall.
http://www.roselandhouse.co.uk
Holders of National Plant Collection of Clematis viticella (cvs)

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.

In article , Kay
writes

The two extremes are probably willow, which re-shoots very easily, and
therefore is often pollarded or cut to ground level, especially if
you're after young shoots for basket work or for their winter colour;
and conifers, which don't like throwing new shoots, so if cut back
either just grow the branches they already have or, if cut right back to
the ground, die.


I cut back a 4 foot variegated Cornus about three years ago, to about a
foot. It 'bled' profusely with a white sticky sort of substance and
never really recovered. So, although books say shrubs such as dogwood
van be pruned back severalty to encourage coloured shoots in the winter,
I guess not all of them like severe hacking!

Janet
--
Janet Tweedy
Dalmatian Telegraph
http://www.lancedal.demon.co.uk