All trees reproduce themselves naturally from seed. Man can secure
their reproduction also from cuttings or layers; and some kinds can
reproduce themselves by shoots from the stump when the parent tree has
been cut. This latter capacity is possessed in a varying degree by
different species; chestnuts, oaks, elms, maples, poplars, and willows
are most excellent sprouters; most conifers do not sprout at all, and
the shoots of those that do sprout soon die (Sequoia or California
redwood seems to be an exception). Sprouts of broad-leaved trees
develop differently from seedlings, growing very rapidly at first, but
soon lessening in the rate of growth and never attaining the height and
perhaps not the diameter of trees grown from the seed; they are also
shorter lived. With age the stumps lose their capacity for sprouting.
To secure best results, the parent tree should be cut close to the
ground in early spring, avoiding severe frost, and a sharp cut should
be made which will not sever the bark from the trunk.
Not all trees bear seed every year, and plentiful seed production,
especially in a forest, occurs, as a rule, periodically. The periods
differ with species, climate, and season.
Not all seeds can germinate, and in some species the number of seeds
that can germinate is very small, and they lose their power of
germination when kept a few hours, like the willows. Others, if kept
till they have become dry, will "lie over" in the soil a year or more
before germinating. The same thing will occur if they are covered too
deep in the soil, provided they germinate at all under such conditions.
In order to germinate, seeds must have warmth, air, and moisture.
The preparation of a seed bed is, therefore, necessary in order to
supply these conditions in most favorable combination. In the natural
forest millions of seeds rot or dry without sprouting, and millions
of seedlings sprout, but soon perish under the too dense shade of the
mother trees.
Man, desiring to reproduce a valuable wood crop, cannot afford to be
as lavish as nature, and must therefore improve upon nature's methods,
making more careful preparation for the production of his crop, either
by growing the seedlings in nurseries and transplanting them, or else
by cutting away the old growth in such a manner as to secure to the
young self-grown crop better chances for life and development.