A primer of forestry by Pinchot Gifford 1865-1946

Author:Pinchot, Gifford, 1865-1946
Language: eng
Format: epub, pdf
Tags: Forests and forestry, Trees. [from old catalog]
Publisher: Washington, Gov't print. off.
Published: 1903-03-25T05:00:00+00:00

THE STRUGGLE CONTINUED.

Those tr('(\s wliicli luivc giiiued thi.s iidviintiigc over tlieir neighl)ors are called dominant trees, while the surviving laggai'ds in the race are said to he overtopped when the}' are hopelessly l)ehind, and retarded when less badlj' beaten. Enormous numbers of seedlings and small saplings are suppressed and killed during the early youth of the forest. In the v'oung crop which we are following man}' thousands perish upon every acre. Even the dominant trees, which are temporarily free when they rise above their neighbors, speedily come into conflict with each other as they spread, and in the end the greater portion is overcome. It is a very deadly struggle, but 3'ear by 3'ear the difl'erences between the trees become less marked. Each separate individual clings to life with greater tenacity, the strife is more protracted and severe, and the number of trees which pei'ish grows liipidly smaller. But so great is the pressure when dense groups of young trees are evenly matched in size and rate of growth that it is not very unusual to tind the progress of the young forest in its early stages almost stopped and the trees uniformly sickly and undersized, on account o,f the crowding.

The forest we have been following has now passed thi-ough the small-sapling stage, and is composed chiefly, but not exclusively, of large saplings. Among the overtopped and retarded trees, which often remain iu size classes which the dominant trees have long since outgrown, there are still many low saplings. Even between the dominant trees, in a healthy forest, there are alwaj'S great differences. Increase in height is now going on ra])idly among these high saplings, and either in this stage or the next a point is reached when the topmost branches make their longest yearly growth, which is one way of saying that the trees make their most rapid height growth as large saplings or smali poles. Later on, as we shall see, these upper branches lengthen much more slowly, until, in standards and veterans, the growth in height is small, and in \cry old trees finally ceases altogether.

NATURAL PRUNING.

While the trees ari' pushing u[) most rapidly, the side l)ranches are "most quickl}' overshaded, and the process of natural pruning goes on with the greatest vigor. Natural jiruning Is the reason why old trees in a dense forest have only a small crown high in the air, and why their tall, straight trunks are clear of branches to such a height above the ground. The trunks of trees grown in the open, where even the lower limbs have abundance of light, are branched either quite to the ground or to within a short distance of it (fig. 21). But in the forest not only are the lower side branches continually dying for want of light, but the tree rids itself of them after they are dead and so frees

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