18 BULLETIN 1496, U. S. DEPARTMENT OF AGRICULTURE _ 
to pine. These lines are located either along subdivision lines, high- 
ways, or old logging railroads, wherever they may be most needed. 
On the Michigan National Forest the fire lines are located largely 
along the main-traveled highways. They consist of two plowed 
strips of six furrows parallel with the highway on each side, each 
strip 7 feet wide and 30 feet from the center of the highway. A 
tractor with a heavy double-disk plow is used to turn over the sod. 
The tractor is also used for pulling stumps. The construction costs 
of such fire lines range from $50 to $75 per mile. The fire lines 
must be kept free of grass or other vegetation. They are, therefore, 
disked twice each year and the grass burned between the plowed 
strips. The width of the fire lines, as well as of the strips between 
them and the highway or subdivision lines, on which the brush or 
tree growth is cut or burned periodically, varies with the fire hazard 
of the locality. : : 
On the Michigan State forests only single fire lines are used 
along subdivision lines. Such lines cost from $80 to $160 per mile. 
The cost of maintaining fire lines ranges from $5 to $18 a mile, 
according to the width of the fire lines and the intervening strips 
and also the age of the lines. With each successive disking the 
maintenance costs are reduced. 
Standards of detection and suppression—The detection force 
should be so organized that it can detect forest fires before they cover 
0.1 acre. In the Lake States that means from 15 to 20 minutes 
after a fire has started. The outbreak of fire should be reported, 
and men should be actually on the fire before it has covered 10 acres. 
Under the conditions ordinarily prevailing in the Lake States that 
would mean within one or two hours after the fire has been detected. 
Of course there may be conditions where such speed would not be 
required, as, for instance, when a fire occurs in a type of forest where 
its spread must be slow or where it can be suppressed most easily 
during the night. The organization, however, should be such that, 
if necessary, a force of men could be put on any fire within one or 
two hours. 
The organization for suppression of fire should be such that on 
an average it would not allow any fire to cover more than 10 acres. 
This of course can not be an absolute requirement, because when con- 
ditions are right fire will spread too rapidly for any normal control 
to be effective. But throughout most of the Lake States the condi- 
tions are such that no fire should remain uncontrolled overnight. 
Generally speaking, fire protection may be considered highly effec- 
tive when the area burned over annually does not exceed five-tenths 
of 1 per cent of the total forest area, or 1 acre to each 200 acres of 
forest under protection. It is fairly effective even if 1 acre to each 
100 acres is burned over annually, a goal that may take yet a few 
years for the Lake States to attain. 
How near or how far the different States of the Lake States region 
are from adequate fire protection may be gathered from the figures 
in Table 4, based on a 10-year average (1916-1925), as ascertained 
in the fire-protection studies of the Lake States Forest Experiment 
Station. The figures for Wisconsin are estimated rather than actual, 
for in this State there are no reliable reports as to the number of 
fires and the area burned over. 
