Dense shade preserves soil moisture, the most essential element for
wood production; a close stand of suitable kinds of trees secures this
shading and prevents the surface evaporation of soil moisture, making
it available for wood production. But a close stand also cuts off side
light and confines the lateral growing space, and hence prevents the
development of side branches and forces the growth energy of the soil
to expend itself in height growth; the crown is carried up, and long,
cylindrical shafts, clear of branches, are developed; a close stand
thus secures desirable form and quality. Yet, since the quality of
wood production or accretion (other things being equal) is in direct
proportion to the amount of foliage and the available light, and since
an open position promotes the development of a larger crown and of
more foliage, an open stand tends to secure a larger amount of wood
accretion on each tree. On the other hand, a tree grown in the open,
besides producing more branches, deposits a larger proportion of wood
at The base, so that the shape of the bole becomes more conical, a
form which in sawing proves unprofitable; whereas a tree grown in the
dense forest both lengthens its shaft at the expense of branch growth
and makes a more even deposit of wood over the whole trunk, thus
attaining a more cylindrical form. While, then, the total amount of
wood production per acre may be as large in a close stand of trees as
in an open one (within limits), the distribution of this amount among
a larger or smaller number of individual trees produces different
results in the quality of the crop. And since the size of a tree or log
is important in determining its usefulness and value, the sooner the
individual trees reach useful size, without suffering in other points
of quality, the more profitable the whole crop.