148 PRACTICAL FORESTRY 
be unable to stand alone were it deprived of support 
from its neighbors. 
Man may introduce an underwood just as has 
often occurred in nature. Let us have an overwood 
of white pine, for instance, a tree which does not 
clean itself well even in dense stand, because it is 
a semi-shade-endurer; and after it is well under way, 
let us plant in its shade maple or beech as an under- 
wood. Let us give to each pine plenty of room, so 
that its crown will fully develop, and produce a large 
quantity of wood. The young maples and beeches 
growing beneath will shade its lower branches so that 
they will die and fall. In that way the underwood 
will clean the boles of the pine and will protect the 
ground, and shed at the same time a rich cover of 
leaves which will fertilize the soil, and stimulate the 
height growth of the pine. In this way a good qual- 
ity of white pine may be produced in a compara- 
tively short time. The soil will improve in quality, 
and there will be yielded besides a large quantity of 
hardwood which may be used in the manufacture of 
barrel staves, wood alcohol, and for fuel. 
Much depends upon the species, however. Some 
trees love a close canopy. Thinning, at best, is a 
delicate operation. It is work which requires con- 
stant supervision on the part of the forester, and the 
work above all others which tests his skill. Good 
