A ]\I E R I C A N SYLVICULTURE 



IV. To reduce the danger ■ from forest fires, insect pests, fungi 

 plagues, wind, snow and sleet. 



V. To remove cripples and wolves. 



VI. Early financial returns. 



VII. Reduction of investment. 



VIII. Shortening of the rotation by feeding a lesser number of 

 mess-mates on a relatively larger amount of food (viz., moisture, 

 heat, light, mineral matter, etc.). 



IX. Regulation of the relative proportion of the species in 

 mixed pole Avoods. 



X. Reducing tlie friction, and the consequent loss of side shoots, 

 between crown and crown. 



B. The season for thinning depends upon local climate, 

 seasonable prices of labor, advisability of peeling and intensity of 

 thinning. The season usually selected for thinning in Europe is the 

 late winter when the main cuttings are completed. 



C. The time for thinning. Thinnings should begin in the 

 late thicket stage and sliould be repeated, to begin with, in five-year 

 intervals, say from the year thirty to sixty. Thereafter the 

 intervals are increased up to the year eighty or ninety. A prepara- 

 tory cutting, although conducted like a thinning, is no thinning, 

 since its purpose is regeneration. Thinnings stop at the end of the 

 pole stage. Where poles are non-salable, thinnings cannot be made. 



To raise homogenous timber, thinnings must be repeated at 

 intervals of four to eight years. 



D. The material obtained from a thinning may consist 

 of firewood, pulp wood, mine props, fence posts, telephone poles, 

 hop poles, hoop poles, tool handles, bolts for spokes, locust pins, 

 tannin wood, etc. 



Twigs and stumps and material almost worthless should be 

 left so as to prevent a deterioration of the soil and so as to stimu- 

 late the bacterial life in the soil. 



In European practice, the number of cubic feet obtained by 

 thinnings during the course of a rotation per acre exceeds frequently, 

 now-a-days, the number of cubic feet obtained by the final cut. 



The tool used for thinning is the axe invariably. 



E. Kinds of thinnings. The old doctrine was : " Thin early, 

 frequently, moderately! " 



This rule has been gradually abandoned during the past twenty 

 years. Tlie method of thinning depends on its purpose. William 

 Schlich distinguished between quality thinnings, made to improve 



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