Ever see a limb just drop from the tree for no
apparent reason? If you live in a wooded lot with
old growth trees, this is probably a common
occurrence. Have you wondered why certain old trees
don't have any branches for the first 20 to 40 feet
of the trunk height?
Well, as trees such
as mighty oaks grow over decades and decades, the
higher branches soon cast a heavy shade on those
below. Eventually, if a branch is denied light, it
cannot support leaves. Without leaves, it cannot
pull water up from the roots so it must die. At this
point, the tree forms a partition zone at the trunk
and, in effect, cuts off the branch. It will soon
begin to rot and eventually drops to the ground
under its own weight.
Fortunately, although
the branch may hurt something as it falls, it does
not hurt the tree. To avoid smashed fences, flower
beds...or worse, keep an eye on the lower branches
of big old trees and have them removed once they no
longer bear any leaves.