THE STEM 127 



spreading. A single match, or the glowing stump of a cigar, 

 carelessly thrown among dry leaves or grass, may start a 

 conflagration that will destroy millions of dollars' worth of 

 standing timber. 



To prevent the spread of fungi, dead trees should be re- 

 moved, and broken or decayed branches trimmed off and the 

 cut surfaces painted. Birds which destroy insects should be 

 protected ; sheep and hogs should be kept out, and dead 

 leaves left on the ground to cover the roots and fertilize the 

 soil with the humus created by their decay. Finally, none 

 but mature trees should be cut for industrial purposes, and 

 the cutting ought to be done in such a way that the young 

 surrounding growth will not be injured by the falling 

 trunks. 



142. The usefulness of forests. — Aside from the value 

 of their products, forests are useful in many other ways. 

 They influence climate beneficially by acting as windbreaks, 

 by giving off moisture (Exp. 58), by shading the soil, and 

 thus preventing too rapid evaporation. Their roots also 

 help to retain the water in the soil, and by this means tend 

 to prevent the washing of the land by heavy rains and to 

 restrain the violence of freshets. 



143. Forests and water supply. — It is especially im- 

 portant that the watershed of any region should be well 

 protected by forests, to prevent contamination of the streams 

 and to insure an unfailing supply of water by checking the 

 escape of the rainfall from the soil. 



Practical Questions 



1. Explain the difference between a forest, grove, copse, wood, wood- 

 land. 



2. In pruning a tree why ought the branch to be cut as close to the stock 

 as possible? (137.) 



3. Name the principal timber trees of your neighborhood. What gives 

 to each its special value ? 



4. Name six trees that produce timber valuable for ornament ; for 

 toughness and strength. 



