116 ELEMENTARY FORESTRY. 
they are unusually destructive, and leave very little humus in the 
top soil. For this reason land that has been burned over in this 
way is a long time in recovering from its injuries. Besides the 
injuries already cited, all forest fires kill or drive out much of 
the game in our forests. 
Spring Fires are very injurious to trees, and especially ten- 
der seedlings, for trees in the spring of the year are full of sap, 
and can endure but little heat. 
Summer and Autumn Fires generally run deep into the 
ground, and if the soil is very dry and of a peaty nature burn off 
» Mi 
Figure 30. A Fire Fall. Roots burned off and trees blown down in 
great confusion. 
the roots of the trees. The result of this is that the trees are 
blown down in great confusion, and form what are known as 
“fire falls.” Where a thick growth falls it forms an almost 
impassable barrier, which remains in this state until decay and 
repeated fires, extending over a long series of years, finally 
destroy the trees, and perhaps get the land into condition for a 
new growth, 
