. The leaves, twigs, branches and trunks of the
trees also soak up considerable moisture. The amount of rainfall
that directly strikes the ground is relatively small. The upper
layer of the forested ground consists of a network of shrubs, and
dead leaves, branches, and moss. This forest carpet acts like an
enormous sponge. It soaks up the moisture which drops from the
trees during a storm. It can absorb and hold for a time a
rainfall of four or five inches. The water that finally reaches
the ground sinks into the soil and is evaporated or runs off
slowly. The portion that is absorbed by the soil is taken up by
the roots of the trees and plants or goes to supply springs and
watercourses.

The power of the trees and forest soil to absorb water regulates
the rate at which the rainfall is fed to the streams and rivers.
Frequently it takes weeks and even months for all the waters of a
certain rain to reach these streams. This gradual supplying of
water to the streams regulates their flow. It prevents floods and
freshets. Careful observation and measurements have shown that
unforested regions will discharge rain water at least twice as
fast as will forested districts.

The stealing of soil by erosion occurs where run-off waters are
not obstructed by forest growth. Silt, sand, and every other kind
of soil are swept from their natural positions and spritted away
by the foaming waters as they surge down the steep slopes. The
stream or river which is flooded by these rushing waters roars
down its narrow channel, tearing loose and undermining the
jutting banks. In some cases, it will break from its ordinary
course to flood exposed fields and to carry away more soil. As
the speed of the stream increases its power to steal soil and
carry it off is increased. Engineers report that the carrying
power of a stream is increased 64 times when its rate of flow is
doubled. If the flow of a river is speeded up ten times, this
raging torrent will be able to carry one million times as much
foreign material as it did when it was flowing at a normal rate
of speed, causing inexpressible damage and destruction of life
and property.

The protection afforded by forests on the water-sheds of streams
furnishing the domestic water supply for cities and towns is
becoming more fully realized. A large number of cities and towns
have purchased and are maintaining municipal or communal forests
for this very reason.

CHAPTER IV

WILD LIFE OF