38 BULLETIN 1496, U. S. DEPARTMENT OF AGRICULTURE 
using industries is not secure. The pulp-and-paper industry in some 
localities is now learning this lesson through bitter experience, and 
the same is true of other industries dependent upon wood. 
Continuous forest production involves a plan of management for 
the property, an inventory of the stand by age classes, and a deter- 
mination of the annual growth and of methods of cutting that will 
insure regrowth on the cut-over land and continuous yields. This 
in turn involves employment of technical experts capable of making 
an intelligent inventory of the forest property, preparing plans for 
its management, and providing technical supervision of the actual 
operation. It means the employment in the lumber industry, as in 
mining and other industries, of men who have had professional 
training within this field. Only a technical personnel, trained for 
the work, can apply intensive methods for handling the forest as a 
crop 
What methods should be applied for the different forest types 
and under the different forest conditions is very difficult to specify. 
Under intensive forest management foresters may use different meth- 
ods of regrowth—for instance, natural reproduction or artificial 
planting—and yet attain the same results. Again, if an aspen stand 
is to be managed for the production of aspen ~pulpwood one method 
may be applied, whereas if the same type is managed with the aim- 
of converting it into a white pine or spruce stand another method is 
necessary. There is no universal method, even for the same type of 
forest, which will invariably produce the best results. Forest prac- 
tice must vary not only with the forest type but also — the pur- 
pose for which the owner may be growing timber. 
RELEASE CUTTINGS, THINNINGS, AND UNDERPLANTINGS 
To utilize fully the productive capacity of the forest soil for the 
best growth of the most desirable trees, it will not be enough merely 
to obtain natural reproduction. The young growth will require tend- 
ing and care. 
When northern hardwoods are cut under the “selective” system, 
the control of the most desirable species in the second growth is 
obtained at the time of cutting by favoring the more-desirable species 
and cutting out the less- valuable’ ones. The same is true in old stands 
of Norway and white pine. In both forests the removal of the 
remaining old stand and after young growth is established and the 
thinning of the young stand if it is too dense are all that may be 
required. 
However, in clean-cutting old stands of northern hardwoods, where 
the character of the second growth is determined largely by those 
species which sprout best either from the stump or from the roots 
or where the proportion of the less-desirable species is likely to 
increase, improvement cuttings are needed after 10 or 20 years. Also 
in dense young stands of jack pine on very poor soils where the 
growth is stagnating thinnings become essential. (Pl. 4.) Where 
aspen and paper birch stands are to be converted into more valuable 
forests underplanting is necessary. 
Second-growth hardwoods, that spring up after the clean cutting 
of the old ; stand, may have to be gone over at an early age and the 
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