552 RELATION TO ENVIRONMENT. 



time will yield the state a revenue sufficient to more than pay 

 for the cost of management, and also will tend to keep within 

 reasonable bounds the price of building materials. 



1038. Forest planting in unforested areas. Successful at- 

 tempts have been made to grow forests in the prairie regions of 

 the West (the "plains" east of the looth meridian) by trans- 

 planting seedlings and cultivating them and protecting them until 

 they are large enough to shade the ground and hold their litter. 

 These forests provide their owner shelter for orchards, provide 

 fire-wood, fence-posts, and some lumber for building material. 

 In Gascony (France) an arid, sandy area was planted with pines 

 to hold the sand. The swamp regions here were also reclaimed 

 by planting forests. What was once an unhealthful area is now 

 a health-resort. Certain species of eucalyptus which grow in 

 wet ground have been planted in swampy lands to drain them. 

 This tree requires a great amount of water and transpires large 

 amounts. 



1039. Enemies of the forest. Outside of the destructive 

 injury of fires, wind, or the careless operations of man, as well 

 as climatic and soil factors which are inimical to forest develop- 

 ment, mention should be made of biotic factors. Many forms of 

 life interfere with the perfect development of trees or act as de- 

 structive agents. Insects feed upon and destroy leaves, branches, 

 and trunks; herbivorous animals feed upon foliage, buds, and 

 twigs. We are concerned here chiefly, however, with plant 

 enemies. These are parasites and wood-destroying fungi. The 

 most important parasites are among the fungi, though some 

 seed plants, like the mistletoe, "beech drops," "pine sap," arceu- 

 thobium, etc., do slight injury to some trees. The parasitic 

 fungi injurious to trees are found among the rusts, mildews, 

 molds, and a few among the mushrooms, black fungi, and cup 

 fungi. The fungi, however, which are more destructive to 

 timber trees are chiefly found among the mushrooms and their 

 near relatives. They are known as "wound" parasites and 

 wood-destroying fungi. It is quite easy in many cases for one 

 possessing no technical knowledge of the subject to read the 



