66 BULLETIN 55, U. S. DEPARTMENT OF AGBICULTUBE. 
2 . The same ground should not be logged too often; say. not oftener 
than every 10 or 20 years. Frequent logging over the same area 
prevents the firm establishment of young growth. 
3. Keep out fires from the logged-over areas. 
This system of gradual cutting, which may be called a selection 
system in groups, is decidedly the most practical, simplest, and 
safest so far as securing natural reproduction of spruce and balsam 
is concerned. Under it, spruce reproduction is favored at the expense 
of balsam, since the openings are small and the light conditions 
more favorable to spruce than to balsam. The greatest advantage 
of the system, however, is the protection which it affords against 
windfall — a very important consideration in all spruce cuttings. 
The system differs from the method of logging practiced 25 to 30 
years ago only in that the trees are cut in small groups instead of 
singly. Many of the old cuttings, when fires were kept out, have been 
cut over for the second and third time. Experience shows that no 
forest has ever been ruined by such a method of cutting. It is the 
recent logging, which amounts to practically clear cutting, especially 
when followed by fires, which has reduced large areas of timberland 
to a state where artificial planting or sowing is the only means of 
bringing them back to forest. 
By clear cutting small groups, opportunity is afforded for utihzing 
all the merchantable timber, especially if the openings are made in 
the older and more mature stands. At the same time, forest con- 
ditions are preserved which are favorable for natural reproduction. 
The danger from windfall under this method is almost entirely 
avoided. 
Cutting to a diamder limit. — Cutting in strips or selection cutting 
in groups requires a careful selection of the logging areas and expert 
technical knowledge. Wherever such knowledge can not be had. 
fight cutting over the entire logging area may roughly answer the 
requirements of natural reproduction of both spruce and balsam fir. 
The higher the diameter limit for both species the more favorable 
will be the conditions for natural reproduction. The diameter limit 
should be raised in thin stands and lowered in dense ones, the main 
point being not to open the stand too heavily and destroy the con- 
ditions under which natural reproduction takes place. Although by 
cutting balsam fir to a lower diameter than spruce some advantage 
may be given spruce in reseeding the ground, yet under such a rough 
system it is difficult to control the conditions under winch one or 
the other species can best come up; the preponderance of spruce or 
balsam fir in the future stand must therefore be left largely to chance. 
