144 PRACTICAL FORESTRY 
and a host of worthless species interfere with the 
better kinds. Aside from the great good accom- 
plished, the forest is improved in appearance by clean- 
ing, which in many instances is a factor worthy of 
much consideration. The removal of dead branches 
might also be classed under the head of cleaning. 
The value of the timber may be much increased in 
this way. A dead branch forms loose knots in boards 
and planks. 
The removal of green branches is called pruning. 
The fewer the branches, the better will be the quality 
of the wood. Trees should be grown in such a way 
that they will naturally shed their lower limbs. Trees 
grown in the open retain their branches close to the 
ground. The greater the power to endure shade, the 
larger will be the amount of limbage which a tree 
develops. On the whole, however, the pruning of 
green branches is not advisable in the forest except - 
for esthetic purposes, because it is expensive, and if 
the limbs are large the wound must be covered with 
antiseptic paint in order to prevent rot. The spores 
of fungi collect on the wounds and cause decay, which 
spreads throughout the whole stem of the tree. If the 
wound exceeds two or three inches in diameter, it 
should be covered with creosote, coal tar, or paint, 
which will prevent the entrance and growth of fungi. 
The cut should be smooth, and great care must he 
