11 



trees; because the trees left for a second cut do not have to be very 

 evenly distributed over the area. Thus, one quarter section may 

 contain an abundance of blackjack and yellow pine suitable to 

 leave for a second cut, whereas an adjoining quarter section may 

 contain mostly yellow pine which can be cut now, and very few 

 seed-bearing blackjacks. Trees below 16 inches in diameter breast- 

 high usually bear only small quantities of seed, and hence will not 

 figure materially in the seed crop for the next few years. Therefore, 

 if immediate reproduction is desired, wherever there are not enough 

 seed-bearing blackjacks the deficiency must be made up from the 

 youngest and best developed yellow pines available, even though 

 not needed for a second cut. The number of trees per acre needed 

 for seed purposes varies greatly with size and condition; on the 

 average, from 3 to 5 yellow pines and about twice as many black- 

 jacks (over 16 inches diameter breast-high) are required. 



Spike tops and burned or decayed trees should always be cut, 

 unless greatly needed for seed purposes. While such trees usually 

 have a high seed-bearing capacity, to leave them standing until a 

 second cut can be made involves merchantable deterioration or 

 total loss. The risk in the case of light burns is comparatively 

 small, but in the case of spike top and decay loss is certain. Since 

 in extreme cases, however, it becomes necessary to leave defective 

 trees for want of anything better, it is well to know that, unless too 

 far gone, such trees can be expected to produce large quantities of 

 superior seed for a number of years. 1 



Trees infested by mistletoe or bark beetles, even though not 

 killed, are of little value for seed, and should be cut as being a menace 

 to the forest. (Instructions in regard to the proper disposal of trees 

 attacked by bark beetles are given in Bulletin 83, Part I, U. S. 

 Department of Agriculture, Bureau of Entomology.) An exception 

 to this rule may be permissible in the case of mistletoe, when the 

 trees are isolated and when the attack is slight, but not in the case 

 of bark-beetle infestation. Further investigations in regard to the 

 effect of mistletoe and bark beetles are needed. 



Isolated trees are preferable to those in close stands; first, because 

 they usually have larger crowns; and second, because they are more 

 windfirm. 



For seed collecting, young trees are most desirable from a purely 

 technical standpoint on account of the high vitality of their seed; 

 but in practice, older trees are preferable on account of their heavier 

 yield, and because the seed from such trees can often be collected 

 cheaply in connection with logging operations. Such defects as 

 spike top, burns, or heart rot are not objectionable; but trees affected 

 by insects or mistletoe should be avoided. 



i Records have been established to determine how long such trees will persist. 

 (Cir. 196J 



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