"gregpresley" wrote:

The living part of the trunk is the outer layer called the cambium. (The
center of the tree is not really alive as we think of the centers of our
bodies as being alive because they are so crucial to our existence - the
center of the trunk doesn't perform any essential function to the tree,
other than hold the leaves up). The cambium can survive injury, but not if
it is injured all the way around the tree - it is the highway that water and
nutrients travel between the leaves and the roots. That is why when people
want to kill trees, they "girdle" them. They tear a layer of the cambium off
all the way around the tree - an impassible road block, the tree dies. I
doubt that your bullet wound girdled the entire cambium of the tree,
therefore I'd expect it to live a long healthy life, unless some disease
organism like a fungus decides to make a home in the hollow.

The above is correct in intent but is misleading in detail.

The tissue on the outer edge of the heartwood is the xylem or sapwood.
The xylem is supportive tissue that forms the vascular paths that carry
water and nutrients from the roots to the leaves. Older xylem becomes
the heartwood. If the xylem is damaged, the branches on that side of
the tree will loose their leaves since they have no way of getting water.

The green layer under the bark but just outside the xylem is the
cambium. The cambium really does nothing to help the tree now, but is
the most important area since it is the growth plate that forms the new
xylem on the inside, new phloem on the outside of it and new cambium to
match the growth of the tree. It is similar to the growth plate of a
bone. It is the only area of a tree that grows besides the buds that
form new roots, new branches, new leaves and new flowers. When the
cambium dies (no longer green), the tree is considered dead. If the
cambium is destroyed all the way around the tree, the tree will function
for a while, sometimes several years but eventually die.

The phloem or inner bark outside the cambium is the vascular tissue that
returns nutrients to the roots to be stored for next years leaves. If
the phloem outside the cambium is destroyed all the way around the tree,
the tree will function for a while, sometimes several years but may
eventually die if the cambium is not protected.

Outside the phloem or inner bark is the regular bark that is composed of
old phloem. It serves to protect the tree.

The bottom line is that the general health of a tree that has sustained
a wound depends on:

1) at the point of impact is enough xylem left to support the leaves. If
yes, then the tree will survive at least a year or two unless it gets
infected.

2) at the point of impact is enough phloem left to support the roots
with nutrients. If yes, than the tree will survive at least several
years unless it gets infected.

3) at the point of impact is enough cambium left to form new xylem and
phloem. If yes, then the tree will live if protected from infection.

The trend to prevent infection is to clean the wound and make sure it
won't trap moisture. Bandaging a tree is used sometimes, but not
always. When bandaging a tree, grafting wax works well.

As an anecdote, I have girdled black walnut trees that were killing my
rhododendrons. I removed the bark, phloem and cambium and the outer
part of the xylem all the way around for over a width of 3 inches. The
trees looked perfectly normal for 3 year. Then the 4th year the leaves
started to come out and then they depleted the roots of nutrients and
died. I was shocked that a girdled tree would last so long. These
trees were about 7 to 14 inches in diameter. I girdled the trees in
order to kill the roots. If you just cut a black walnut tree down, it
will send up suckers for many years, what seems like an eternity.

--
Pardon my spam deterrent; send email to
Visit my Rhododendron and Azalea web pages at:
http://home.earthlink.net/~rhodyman/rhody.html
Also visit the Rhododendron and Azalea Bookstore at:
http://home.earthlink.net/~rhodyman/rhodybooks.html
Cheers, Steve Henning in Reading, PA USA http://home.earthlink.net/~rhodyman