Stan The Man writes
In article ,
wrote:


If the full circumference is stripped I fear you will lose the tree as
the sap won't be able to travel up to the leaves. In any event it is
likely that there will be no new growth above the stripped bark albeit
you may get some new growth at ground level. Cork trees seem to cope
well when their bark is stripped/harvested but they are an exception.

I've always wondered about that. Is the explanation that it's not
actually the bark itself that carries the sap up the tree but the very
thin layer just inside it (phloem????), and which is destroyed in most
trees when you remove the bark. But on a cork oak the bark is so thick
you can remove the bark without removing that layer? Or is the layer
also thicker on a cork oak?

I believe that cork is harvested from the outer layer of the bark but
the more likely reason for the tree's survival and bark regeneration is
that the bark is stripped in a spiral and so the stripping never
completes the fatal circle.

That method of cutting doesn't tie up with what I've observed in
Portugal, which is that the circumference is completely stripped and the
removed pieces of bark form a cylinder with vertical cut, with no
indication that the cut edges don't match up perfectly.

Googling suggests you're right in that it's only the outer layer, eg:

(from http://www.killerplants.com/weird-plants/20040101.asp)

"Cork oaks produce a unique bark. Phloem and xylem derive from the
cambium, a thin cylinder of actively dividing cells in the trunk and
branches. Phloem tissue is created to the outside of the cambium; xylem
to the inside.

As the tree grows in diameter, xylem becomes wood; phloem becomes bark.
In the cork oak, the cambium is called the "mother of cork".

Unlike most trees that shed the outermost layers of bark, the cork oak
retains its bark. The bark is insulating--it protects the living cambium
from heat. The bark is lightweight, crossed by lenticels or pores that
allow the exchange of gases between the living cells and the atmosphere.
The bark is fire-resistant; the outer layers will char, but not burn,
during a wildfire."

.... in other words, it's as if a birch tree, say, didn't shed all those
lovely sheets of paper and instead stacked them up until we harvested
them in one go several years later.

--
Kay