FOREST FIRES. 115 
from insects and fungus diseases. This is most evident in the 
case of White Pine, Birch, Poplar and similar soft woods, but 
even hard woods are injured by insects if allowed to stand long 
alter being killed. 
The Killing of Half-Grown Trees by forest fires causes 
aloss that amounts not only to the value of the timber trees but 
to the value of the seeding and shading trees and the forest 
floor. The value of the trees alone in this case is not a fair 
standard by which to measure the loss, since at this stage of 
their growth they are making their most rapid increase, and 
their value should be computed as the amount upon which the 
increase is paying a good interest. For instance, the Division 
of Forestry of the Minnesota Experiment Station found land 
that was well stocked with young White Pine (six inches in 
diameter and fifty feet high) that could be bought for about one 
dollar per acre, and yet the annual increase on the trees would 
day five per cent on a valuation of $100,000 for the next twenty 
years. The reason why such a state of affairs exists is that there 
is such great danger from fire that the investment fails to com- 
mand the money of careful investors. 
The Destruction of the Forest Floor by fire greatly les- 
sens the probability of an immediate renewal of valuable tree 
growth upon the land, and therefore is one of the greatest 
injuries to forests. The valve of the forest floor can hardly be 
estimated, but the expense that would be necessary alter a fire 
to produce conditions as favorable to the seeding of our timber 
lands as those found in unburned forests would probably be not 
less than twenty-five dollars per acre. 
Light Fires, which repeatedly run over the ground, and 
which by the casual observer are thought to be of no impor- 
tance, often destroy the seeds in the surface soil and the young 
tree seedlings, besides injuring the forest floor, and unless such 
fires are prevented it is impossible to secure a good growth of 
timber on any land. The fires that burn over the land shortly 
alter it has been logged, and which feed on the tops and other 
waste parts of the trees, generally destroy a large number of 
young seedling trees, perhaps all of them, so that in order to 
secure a new growth seeds must be brought from a distance. 
Owing to the great heat developed by such fires in dry weather, 
