BUDS AND STEMS 117 



I*ark, with over 1,000,000 acres of timber land, and other states are fol- 

 lowing her example. 



Methods for keeping and protecting the Forests. — Forests should 

 be kept thinned. Too many trees are as bad as too few. They struggle 

 with one another for foothold and light, which only a few can enjoy. Several 

 methods of renewing the forest are in use in this country. (1) Trees may be 

 cut down and young ones allowed to sprout from cut stumps. This is 

 called coppice growth. This growth is well seen in parts of New Jersey. 

 (2) Areas or strips may be cut out so that seeds from neighboring trees 

 are carried there to start new growth. (3) Forests may be artificially planted. 

 Two seedings planted for every tree cut is a rule followed in Europe. The 

 greatest dangers are from fire, which often devastates large areas, and 

 from careless cutting. 



The Economic Value of Trees. — Trees form a protective cover- 

 ing for the earth's surface. They prevent soil from being washed 

 away and they hold moisture in the ground. This they do because 

 the evaporation of moisture through the stomata of the leaves cools 

 the atmosphere, thus tending to precipitate the moisture in the 

 air. Without trees many of our rivers might go dry in summer, 

 while in the rainy season sudden floods would result. This has 

 occurred in parts of Switzerland, France, and in Pennsylvania, 

 where the forest covering has been removed. In some localities 

 forests are used as wind-breaks and to protect mountain towns 

 against avalanches. Thus in winter they moderate the cold, and 

 in summer reduce the heat and lessen the danger from storms. 

 The nesting of birds in woods protects many plants valuable to 

 man which otherwise might be destroyed by insects. 



Wood has great commercial importance as well. Even in this 

 day of coal, wood is still by far the most-used fuel. It is useful in 

 building. It outlasts iron under water, in addition to being dura- 

 ble and light. It is cheap and, with care of the forests, inex- 

 haustible, while our mineral wealth will some day be used up. 

 Hard woods are chiefly used in house building and furniture manu- 

 facture; the soft woods, reduced to pulp, are made into paper. 

 Distilled wood gives alcohol. Partially burned wood is charcoal. 

 Vinegar and other acids are obtained from trees, as are tar, creo- 

 sote, resin, turpentine, and other useful oils. 



Modified Stems. — Stems, as well as roots, may be modified or changed 

 to adapt these parts of the body to their surroundings. As we have learned 



