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BULLETIN 544, U. S. DEPARTMENT OF AGRICULTURE. 



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and birch firewood, spools, novelties, and the like. A permanent 

 market for spruce of the quality produced would also be necessary. 



IMPROVEMENT CUTTINGS. 



With forests of the selection or many- 

 aged form, thinnings, strictly speaking, 

 merge to such an extent with the opera- 

 tions of harvesting the mature crops as 

 to lose their identity. Thinnings and 

 like operations, therefore, are applied 

 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- 

 nings. Pruning is also an improvement 

 operation, but in this country, and par- 

 ticularly in the case of spruce, will be 

 scantily employed. Pruning involves a 

 direct investment of money from which 

 only an indirect benefit is derived . With 

 a short rotation, pruning makes possible 

 the securing of a larger percentage of 

 clear logs capable of yielding upper 

 grades of lumber. Aside from so-called 

 " fiddle butts ' ' for piano board and violin 

 stock and clear logs for siding material, 

 the difference hi price at the present time 

 between the various grades of spruce will 

 not justify an investment for pruning. 

 Cleanings. — Cleanings are particu- 

 larly adapted to bring about favorable 

 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- 

 growing beech and sugar maple may be 

 removed from young stands, and the 

 birch and popple thinned. The most 

 advantageous time is about the fifth 

 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 



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