38 BULLETIN - 418, U. S. DEPARTMENT OF AGRICULTURE. 
Yellow pine in its middle life and old age demands so much 
light and ground space that the soil is put to the most intensive use 
only when the forests are uneven-aged, so that the younger trees mav 
pass their slow-growing sapling stage in the gaps between the big trees. 
The system of cutting which seems to be ideal for this type of 
forest is a form of selection cutting. Periodic cuttings are made, 
in each of which all the overmature and thoroughly ripe trees in the 
stand and all the defective ones are removed; and the saplings, 
poles, and young, thrifty trees are left standing to form the basis 
for the next crop. No tree is removed until it has reached its major- 
ity, so to speak, and no old, slow-growing tree is allowed to stand 
and occupy space which should be devoted to young and rapid- 
growing trees. In this way the forest is kept at its maximum pro- 
ductivity and the continuity of the forest cover is not interrupted. 
In each cutting, under the practice of the Forest Service in Oregon, 
from 10 to 30 per cent of the volume of the stand (above 12 inches 
in diameter) is left. This is equivalent to 55 per cent of the trees 
over 12 inches in diameter by number. It is anticipated that a 
cutting of this character may be made at intervals of from 40 to 60 
years, and that there will be a yield sufficient to justify logging. 
Each tree which is to be cut is marked or ''blazed'" with an ax 
by a woodsman who has experience, a trained eye, and good judg- 
ment. He decides for every tree as he passes through the forest 
whether it shall be cut or reserved. A woodsman may effectually 
mark in a day 40 acres, or hah a million feet. It is customary to 
set an approximate diameter limit of from 16 to 22 inches, the 
majority of the trees above which limit are cut, and those below 
left; in actual practice this diameter limit must be very elastic, it 
often being wise silviculturally to reserve a tree 30 or more inches 
in diameter while one of 14 inches must be cut. 
The following classes of trees should be cut. They are arranged 
according to the desirability of their removal: 
(a) All spike-topped, seriously fire-scarred, lightning-struck, or 
otherwise defective, yet merchantable, trees. 
(b) All insect-infested and conky trees. 
(c) All suppressed trees which apparently would not thrive and 
make good growth even if released. 
(d) All thoroughly mature trees of all species which apparently will 
not survive until the next cutting. (In this class should be included all 
trees liable to windthrow, which is a serious menace on certain sites.) 
(e) Enough of the younger trees which would probably survive 
until the next cutting to give the remaining trees plenty of room for 
optimum growth and allow the saplings and seedlings to receive over- 
head light. 1 The cutting, therefore, should be in the nature of an 
improvement cutting. Though the trees that are left are not 
reserved as seed trees, but rather as the basis for the next cut, many 
1 Manuscript report by Forest Supervisor M. L. Merritt. 
