#101 EspritBonsaiInternational - 41Asusedbyhumans
Humanshavealwaysfounda
useforthebarkoftreesandnot
justasa woodby-product.They
soonrecogniseditsvariousvery
usefulproperties,andit was
usedincountlessways.Birch
barkwasusedtomakecanoes,
andtowaterproofroofs;oak
barkwasusedtomakecorks
andtanninsforleatherwork.
Thenumberofimportantmedicinesthatderivefrom
treebarkisimpressivesuch
as,aspirinfromwillow,taxol
fromyew,betulinfrombirch,
orquininefromPeruvianbark
(Cinchonaofficinalis, asmall
South American tree).
And one could readily
bet that there are many
more discoveries to be
made from bark.One can clearly see the
slow flaking process on
this Austrian black pine.
Moss and ivy find a
welcoming support on
the trunk of this Linden.The bark on this larch reveals its age – its
shoots show its eternal springtime youth.Moss takes advantage of this cavity formed when
the bark of this mountain pine was torn away.Without their bark, trees would dry out and
become vulnerable to parasites and fungus. The
bark’s protective role is obvious. However, the
characteristics of bark adapt to the demands and
constraints of the specific natural habitat of each
species.
A protective barrier
The bark of cork oak or of the sequoia is so thick
(up to 60 cm/24in.) that it protects the trees from
forest fires that regularly burn their biotopes. The
silver birch, thanks to its white bark, is less vulne-
rable to the sun’s rays. In the same conditions, the
fine, dark grey bark of the beech would suffer from
the sun’s rays, followed by necrosis which would be
extremely harmful to its health: an unlikely situa-
tion for this forest dweller, unless it was violently
exposed to the sun’s hostile rays. On the other
hand, its smooth bark facilitates the flow of rainwa-
ter towards the ground and roots that the dense
forest canopy and leaves could take up all summer.
One could find many more examples of this sort.
Trees being immobile have no choice but to adapt
every part of themselves to their environment.
Protection is also chemical. Bark is impregnated
with many components such as resins and tannins
and not only the bark of conifers. When part of the
bark is torn, exposing live tissue, these substances
play a part in defending the tree from fungi.
A haven of biodiversity
Thus, bark is far from being merely decorative,
even though, for the tree lovers that we are, this
is the aspect that most concerns us. Bark has
numerous functions essential to the survival of
trees and is the result of a slow adaptation to their
environment.
But bark means even more than this: it is nearly
always accompanied. One can find small organisms
such as lichens or moss, as well as climbing plants
or ferns. All these epiphytic plants take advantage
of irregular and rough textures of the bark to cling
to and benefit from a friendlier environment than
the one on the ground. So bark also plays the role
of host; so much so that tropical trees become a
veritable haven of biodiversity; which is also true,
to a lesser extent, of trees in our latitudes.
It is an interesting paradox to think that bark
protects the tree from some foreign organisms,
but at the same time will welcome others. Clearly,
trees cannot live alone. They are at the centre of
biodiversity and are its guarantors. Every tree is a
little world in itself. �