THE FOREST IN RELATION TO MAN 555 



forested, and this process is under way in many parts of the country. 

 There is a great deal of worn-out agricultural land and sand-dune land 

 that would be well suited to forests. In many cases all that is needed is 

 to protect the young growth from fires. Another method of extending 

 the area of growth is by fuller stocking of existing forest lands. Thus, 

 some trees are found growing so close together that they never become 

 thick enough to be of great value for timber ; but in other forests the 

 trees are so far apart that valuable space is allowed to go to waste. By 

 selecting trees suitable for a given region, and starting the young plants 

 rather close together and then thinning out carefully, the amount of 

 timber grown on a given area can be greatly increased. 



399. Increasing wood yield. It is likely that not more than from 

 70 to 100 of the nearly 1000 native species in this country are worth 

 growing from the economic point of view. The red cedar grows very 

 slowly; the white pine or the red oak could be grown in the same soil to 

 great advantage. We could replace the red spruce in New England by 

 the Norway spruce, just as many areas of France denuded by the World 

 War, as well as other European regions, are being restocked with Douglas 

 fir imported from this country. In some localities we may perhaps find 

 foreign trees better suited to our purposes than the native trees. In the 

 course of a number of years the rapid varieties will yield much more 

 timber than the others ; but rapid growth is not of itself a deciding fac- 

 tor, for it is necessary to consider the toughness of wood and other 

 quahties. The whitewood, or tulip tree, grows much faster than the 

 oak, but it can never be used as a substitute for the oak. 



400. Improving wood quality. Without increasing the actual 

 amount of growth, it is plain that the value of the growth can be in- 

 creased if the trees do not have curved or twisted trunks or branches. 

 By concentrating the growth in the best trees through thinning out the 

 crooked or twisted ones it is possible to increase the yield of a forest area. 



401. Avoiding wood waste. In the national forests the lum- 

 bermen are given a practical demonstration of the value of 

 scientific cutting, seeding, reforesting, etc., and also of the 

 economical handling of growth. Damage to trees often results 

 from careless lumbering. The tree that is being cut down is 

 sometimes damaged, and it is sometimes allowed to injure trees 

 that are left standing. When wood was cheap, a great deal from 

 each tree was left to rot on the ground. Now everything that 

 can possibly be used is saved, and the remaining brushwood is 



