126 
PRACTICAL COURSE IN BOTANY 
ones, or the reforestation of tracts from which the timber has 
been destroyed. Forests may be either pure, that is, com- 
posed mainly of one 
Fig. 145.— After the forest fire. 
kind of tree, as a pine 
or a fir wood ; or mixed, 
being made up of a vari- 
ety of different growths, 
as are most of our com- 
mon hardwood forests. 
140. Enemies of the 
forest.— The first step 
in the preservation of 
our forests is to know 
the dangers to be 
guarded against. The 
chief of these are: 
(1) fires; (2) the igno- 
rance or recklessness of 
man in cutting for 
commercial purposes; 
(3) fungi; (4) injurious insects; (5) sheep, hogs, and other 
animals that eat the seeds and the young, tender growth. 
141. How to protect the 
forests.— The annual de- 
struction of forests by fires 
probably exceeds that from 
all other causes combined. 
The only effectual safeguard 
against this danger is watch- 
fulness on the part of every- 
body. We can each one of 
us help in this work by at 
least being careful ourselves 
never to kindle a fire in the 
woods without taking every 
precaution against its 
Fig. 146, — Oyster fungus on linden. 
