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, 
