CHOICE OF SPECIES IN ARTIFICIAL REGENERATION 37 



species vary greatly in the minimum of soil fertility under which 

 they can be profitably grown. Among indigenous species useful 

 in artificial regeneration the least exacting are pitch pine, red pine, 

 western yellow pine, jack pine, loblolly pine, paper and gray birch, 

 poplar, and locust. Among the most exacting species are walnut, 

 ash, cherry, tulip, and beech. Among intermediate species are 

 Douglas fir, most spruces, and white pine. 



In general, our useful broadleaved species are more exacting 

 than the inferior hardwoods and the conifers. Deviation from the 

 best forest soil toward a shallow, gravelly or sandy soil brings 

 about a dearth in soil moisture and soil nutrients. Deviation to- 

 ward stiff clays and other fine-textured soils brings about an excess 

 of moisture and imperfect aeration. On the whole, sandy and 

 gravelly soils are best suited to species which develop a deep root 

 system, as illustrated in red cedar, pitch pine, white pine, and up- 

 land oaks. Fine-textured soils like heavy clay are best suited 

 for shallow-rooted species such as beech, maple, and cherry. 



27. OTHER FACTORS OF THE SITE WHICH INFLUENCE THE 



CHOICE OF SPECIES 



Where the atmospheric and soil factors are favorable, other 

 factors of the site may inhibit the successful growth of a given 

 species. Species differ in their degree of resistance to injury from 

 external causes such as fire, insects, fungi, grazing, and inun- 

 dation. 



28. Fire. The fire hazard is one of the most important of 

 these factors. At present in most parts of the country it is 

 the greatest risk with which artificial regeneration is attended. 

 Wherever seeding and planting is done every precaution must be 

 taken to minimize this risk. When danger from fire is not under 

 reasonable control seeding and planting should not be attempted. 

 The choice of species is an important factor in reducing the risk. 

 The greatest danger from fire is to be apprehended with coniferous 

 species, particularly with the various species of pine. The least 

 danger usually occurs with dense-foliaged deciduous species in 

 which the bark is thick and the roots are deep in the soil. 



29. Insects. Some species are excluded from use in certain 

 localities due to danger of their total destruction or severe injury 

 by insects. Thus the planting of white pine in pure stand in 

 portions of New England cannot be recommended because of 



