52 THE SEED TREE METHOD 



groups will average longer than between single seed trees and 

 are apt to become so great as to prevent dissemination of the 

 seed over the entire area. This affects reproduction not only- 

 through a poorer distribution of the seed but also by reducing 

 the shght amount of protection to soil and seedlings afforded 

 by the scattered seed trees. (See Fig. 15.) 



In a mixed stand a windfirm species sometimes can be 

 included in a seed group for the purpose of furnishing sup- 

 port to a species easily windthrown which it is desired to 

 reproduce. There is danger of course that the windlirm 

 species may estabHsh its own reproduction. 



Reserve Seed Tree Method. — In certain cases the seed tree 

 method may be appHed not only with the idea of securing a 

 new crop of natural reproduction but also with the purpose 

 of reserving a portion of the mature stand for rapid increment 

 during a second rotation. In this modification of the method 

 the seed trees are selected not only for their capacity to fur- 

 nish seed but also to grow rapidly, and remain thrifty during 

 a second rotation. At the end of this second rotation the 

 new crop is ha'rvested together with the seed trees left at the 

 beginning of the rotation. Some timber of exceptional size is 

 produced. 



The reserve seed tree method cannot be used with every 

 stand. For its successful application the stand must be of 

 moderate age when reproduced with the individual trees still 

 thrifty and capable of withstanding the change in site condi- 

 tions, due to the cutting, and of responding with increased 

 growth. In stands past maturity this method cannot be 

 successfully applied. 



Dominant trees of as little present commercial value as 

 possible are chosen: but they must be dominant, thrifty trees. 

 As a rule healthier and better quahty trees are left as seed 

 trees than under the scattered seed tree method. The num- 



