CHOICE OF SPECIES IN ARTIFICIAL REGENERATION 19 



do well during their early life but gradually fall off in growth or 

 fail altogether after 20, 30 or more years, or before they reach 

 merchantable size. This is particularly true of species not climati- 

 cally adapted to the site, which is quite likely to be the case when 

 exotics or trees from remote regions are used in restocking. 



Photograph by U. S. Forest Service 



FIG. 9. Plantation of blue gum (Eucalyptus globulus) 28 years 

 old. California. 



4. FACTORS UPON WHICH THE CHOICE OF SPECIES DEPENDS 



The desirability of a given species for use in seeding and plant- 

 ing depends upon a large number of variable factors, the most 

 important of which are as follows: 



a. The closeness of the correlation between the site factors 

 and the silvical requirements of the species. 



6. The suitability for the particular object in view. 



c. The adaptability for management under the required silvi- 

 cultural system. 



d. The effect of the particular species upon the site. 



e. The cost of reproduction, rapidity of growth, and resistance 

 to injury. 



