IMPROVEMENT CUTTINGS 79 



of reproduction. In Fig. 29 a middle-aged stand is shown with 

 older trees interfering. Here the crowns of the main stand have 

 reached the crowns of the interfering trees and are already some- 

 what deformed. If the cutting were delayed much longer the 

 stand would be seriously injured. 



The material removed in liberation cuttings is of merchantable 

 size either for timber or cordwood, but is usually of poor quality, 

 being knotty and frequently extremely limby. From the size 

 of the trees to be cut it often appears that a handsome profit can 

 be made, but owing to the scattered location of the trees singly 

 among younger trees, the logging is usually expensive and the 

 trees, on account of their widespreading crowns and large limbs, 

 are hard to cut up. In most cases the trees can be disposed 

 of for enough to at least pay the costs of the operation; so 

 that no financial loss is ordinarily required in making hberation 

 cuttings. 



Liberation cuttings are needed especially in abandoned fields 

 which have gradually reverted to forest, or on cut-over lands 

 where in previous cuttings poor individuals had been allowed to 

 stand. 



As liberation cuttings pay for themselves they have a wider 

 range of application in practical work than do cleanings, but at 

 the same time, since the material removed is of a low grade, it 

 cannot readily be sold where the markets are poor. A good rule 

 is to make liberation cuttings wherever the material will at least 

 cover the cost of removal. 



3. Thinnings. — As a young stand of trees grows older, indi- 

 viduals which at first had ample space for development become 

 crowded. There commences a struggle between them, which 

 becomes more intense year by year, for Hght, growing space, 

 moisture, and nourishment. As the struggle goes on certain 

 trees obtain a slight advantage over their neighbors and may 

 finally succeed in completely overtopping and kilhng them. In 

 accompKshing this, however, the leading trees, as well as those 

 overtopped, are inevitably restricted in crown development, and 

 therefore are retarded in rate of growth and prevented from 



