70 SEEDING AND PLANTING 



pine is acceptable over most parts of the natural range of both 

 species. These two species naturally grow together, and when 

 planted in mixture the plantation suffers less from weevil damage 

 than when white pine is planted pure. 



12. Temporary Mixtures 



In some instances it is more advantageous for the mixture to 

 be temporary, all but one species being removed before the ma- 

 turity of the crop. Such mixtures are useful in the following 

 cases : 



a. When the rapid growth and high value of one or more of 

 the species make it economically advantageous to remove them 

 as thinnings, letting the remaining species form the final crop. 



b. When the original cost of the seeding or planting can be 

 materially reduced by the use of so-called fillers, i.e., inexpensive 

 species which serve to occupy a portion of the area, but which 

 are removed in the early thinnings. 



c. Where a nurse must be provided to protect a tender species 

 during its early life. 



13. THE USE OF FILLERS 



The only reason for the use of fillers in planting operations is 

 the relative cheapness of the stock. In the use of fillers the ex- 

 pectation is that they will be suppressed and crowded out by the 

 crop trees, taken out in the early thinnings, or form a second story 

 under the crop trees. Even when the expense is somewhat re- 

 duced the use of fillers is seldom justifiable. Certainly the use 

 of hardwoods as fillers in planting white pine should be dis- 

 couraged. 



14. THE USE OF NURSE TREES 



Much discussion has been given to the use of nurse trees in 

 seeding and planting in this country. In most instances where 

 nurse trees have been used the resulting stand has not been im- 

 proved, but in many cases, due to their rapid growth, shade- 

 producing qualities, or their abundance in the stand, the crop 

 trees have been dwarfed, suppressed or killed by them. Gray and 

 paper birch, aspen and similar light-foliaged species, which make 

 rapid juvenile growth but which do not attain large size, are the 

 most acceptable as nurse trees. 



