PRUNING OF FOREST TREES. 69 



shoots spring from the cuts, and these are again cut when of 

 suitable size. What has been said in regard to the season and 

 manner of cutting in the previous paragraphs is practically true 

 here. This process is mostly used in the case of willows and 

 poplars to obtain material for basket work, small poles, fuel, etc. 



Time of Rotation is a term used to indicate the age to 

 which trees are grown. The length of this time will depend on 

 the species and on the conditions. For some species not less 

 than eighty years should be allowed for full maturity, while still 

 others may be successfully worked on a thirty-year rotation 

 period. It is not used in the same sense as in ordinary agri- 

 cultural operations, where it signifies frequent changes of the 

 crop for several years with a view to getting the most out of the 

 soil. Since trees do not impoverish the soil, but improve it, 

 there is no necessity for any such method of rotation in forestry 

 as there is in agriculture. 



Pruning of Forest Trees is generally an expensive opera- 

 tion and little is required if trees are properly crowded when 

 young, so that they take on an upright form free from side 

 branches. If they are not crowded when young, many side 

 branches are formed, which generally die out when the trees get 

 large enough to shade all the ground. In some cases these dead 

 branches drop quickly to the ground, and in others they remairf 

 for years, producing knots and irregularity in the wood formed 

 in the meantime and should be removed. Trees grown in the 

 open retain their lower branches more or less throughout life 

 and they produce in consequence timber of inferior value as 

 compared with trees grown in crowded woods. 



Large wounds made by cutting off green branches should be 

 covered. It is often desirable to remove dead branches and it 

 is the practice to do so in some of the plantings of Wnite Pine 

 that have been made in New England. It is said that the lum- 

 ber there is so greatly improved by so doing that the operation 

 is a paying one. But under ideal conditions for the develop- 

 ment of timber trees very little is gained by pruning. 



The Young Growth is Often Injured in ordinary lumber- 

 ing operations by the felling of the trees, which bend them to the 

 ground and often break them. Where special care is desired to 

 protect the young growth it may be desirable to lop off the 



