forester cuts his mature trees, only, and generally leaves a sufficient
number on the ground to preserve the forest soil and to cast seed for
the production of a new crop. In this way, he secures an annual output
without hurting the forest itself. He studies the properties and values
of the different woods and places them where they will be most useful.
He lays down principles for so harvesting the timber and the
by-products of the forest that there will be the least waste and injury
to the trees which remain standing. He utilizes the forest, but does not
cut enough to interfere with the neighboring water-sheds, which the
forests protect.

[Illustration: 123.--A White Pine Plantation, in Rhode Island, Where the
Crowns of the Trees Have Met. The trees are fifteen years old and in
many cases every other tree had to be removed.]

Forestry, therefore, deals with a vast and varied mass of information,
comprising all the known facts relating to the life of a forest. It does
not deal with the individual tree and its planting and care,--that would
be arboriculture. Nor does it consider the grouping of trees for
aesthetic effect,--that would be landscape gardening. It concerns itself
with the forest as a community of trees and with the utilization of the
forest on an economic basis.

Each one of these activities in Forestry is a study in itself and
involves considerable detail, of which the reader may obtain a general
knowledge in the following pages. For a more complete discussion, the
reader is referred to any of the standard books on Forestry.

The life and nature of a forest: When we think of a forest we are apt to
think of a large number of individual trees having no special