52 
BULLETIN 541, U. S. DEPARTMENT OF AGRICULTURE. 
and birch, firewood, spools, novelties, and the like. A permanent 
market for spruce of the quality produced would also be necessary. 
IMPROVEMENT CUTTINGS. 
-f^! 
| With forests of the selection or many- 
| aged form, thinnings, strictly speaking, 
M merge to such an extent with the opera- 
Is tions of harvesting the mature crops as 
•| to lose their identity. Thinnings and 
| like operations, therefore, are applied 
g to such forests only as are even-aged 
| throughout or are made up of even- 
| aged groups. 
| Improvement cuttings are divided 
| successively into the following classes: 
| cleanings, liberation cuttings, and thin- 
a nings. Pruning is also an improvement 
| operation, but in this country, and par- 
>> ticularly in the case of spruce, will be 
go scantily employed. Pruning involves a 
s direct investment of money from which 
| only an indirect benefit is derived. With 
| a short rotation, pruning makes possible 
■s the securing of a larger percentage of 
g clear logs capable of yielding upper 
m grades of lumber. Aside from so-called 
.| l ' fiddle butts ' ' for piano board and violin 
| stock and clear logs for siding material, 
| the difference in price at the present time 
| between the various grades of spruce will 
I* not justify an investment for priming. 
1 Cleanings. — Cleanings are particu- 
| larly adapted to bring about favorable 
■g results in the mixed spruce and hard- 
| wood growths which come in after clean 
■§ cutting and burning. Such worthless 
| material as fire cherry and the slow- 
, g growing beech and sugar maple may be 
t removed from young stands, and the 
| birch and popple thinned. The most 
i advantageous time is about the fifth 
g year after the spruce has come in under 
the hardwood cover, since at that age 
spruce has fully established its roots in the mineral soil and is ready to 
grow rapidly in height. Cleanings may also be resorted to in old-field 
