Wherever it is possible for them to grow,
trees form an important feature of the
landscape. They provide shelter, materials
and fuel for human use, and are a habitat
for countless birds, insects, animals and
micro-organisms. Together in a forest, trees
form the tallest and most impressive plant
community on Earth.
In terms of a brief human life, a forest may
seem to be permanent and unchanging. But
this apparent static quality is an illusion ;
a forest, like a single tree, - and indeed like
our own bodies and beings - is a flux, a
flowing, dynamic inter-relationship of
minerals, energy and time.
Trees and forests have been around for a
lot longer than humans have.
Today's forests are similar to those of
sixty million years ago - tropical rainforest,
jungle and temperate woodland, together
with herbaceous plants occuring wherever
there is sufficient light.
Every tree is a living watercourse ; its roots,
trunk, and branches conduct water up from
the soil to the leaves, from which the water
evaporates into the atmosphere, as a link in
the global cycle of clouds, rain, rivers and
oceans.
Microscopic organelles in the leaves of the
tree build up sugars and starches through
the transmutation of sunlight and water.
Water and minerals are absorbed from the
soil by fine hairs on the tree roots, passing
up the trunk and along the branches and
twigs to the leaves, where 99 percent of the
water is transpired into the air through tiny
pores in the leaf surface called stomata.
Thus, there is a continuous movement of
water through the tree.
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