66 SEEDING AND PLANTING 



d. Intolerant species should not, as a rule, be seeded or planted 

 in mixture. It is sometimes advisable, however, to grow intoler- 

 ant trees in mixture on very good soil when there is no danger 

 from soil deterioration. 



e. Intolerant species should be introduced into tolerant species 

 individually and not in patches or groups except under special 

 conditions such as great variability in the soil, more rapid height 

 growth in the tolerant species, and when standards are retained 

 for the second rotation. 



8. Advantages from Mixed Regeneration when Correctly Made 



Although more difficult to attain, advantages result from 

 mixed crops when composed of suitable species in the proper pro- 

 portion. The more important of these advantages are as 

 follows : 



a. Where the mixture is suitably arranged the site is more 

 completely utilized, which results in an increased production of 

 wood. 



b. Shallow-rooted species when mixed with deep-rooted ones 

 produce stands which suffer less from high winds than is the case 

 where a single shallow-rooted species is used. 



c. Tender species suffer less from frost, snow, and excessive 

 drought when grown in mixture with more hardy species. 



d. Usually fungi and insects are less harmful in stands com- 

 posed of two or more species because the damage is usually con- 

 fined chiefly to but one of the species in the mixture. 



e. The fire danger is usually much greater in a stand composed 

 of a single species, particularly if it be a conifer. The danger is 

 much less if the conifer is mixed with broadleaved species. 



/. Mixed crops can be grown on sites too poor for pure stands, 

 particularly where the species forming the pure stand is an exact- 

 ing one. In the mixed stand, the different species draw upon 

 different depths of soil and make different demands upon the site. 



g. In cases where the early thinnings of a species in pure stand 

 are of little value, more valuable thinnings may be realized by 

 mixing with it one or more species which realize better prices in 

 small sizes. 



h. When serious mistakes have been made in artificial re- 

 stocking through poor judgment in the selection of species, they 



