ROLE OF FIRE IN CALIFORNIA PINE FORESTS 59 
two-thirds of the total area, which was the portion actually covered 
by the fire. 
That the insect epidemic was not lessened but actually accelerated 
was proved by the fact that the owner in the year following the fire 
concentrated insect-control operations on the burned area, practically 
following the methods used by the Bureau of Entomolgy. The trees 
burned down by the light-burning operation became a center of infesta- 
tion. The next year the insect-control crews of the company found 
it necessary to treat these very trees to protect the remaining stand- 
ing timber. In other words, the burning operation did not accomplish 
its major purpose, the control of the insect infestation. 
At the time of the 1921 examination a practically continuous layer 
of new litter had formed on the burned area and fire would again have 
covered essentially the same ground as before. The California For- 
estry Committee in an examination of the area at the time of burning 
(4) reached the unanimous conclusion that there had been only slight 
reduction of hazard, which, as a matter of fact, was originally low, 
as proved by the fact that the burning could be done during the 
summer months with only occasional flare-ups and without losing 
control of the fires. This operation demonstrates further that light 
burning, even when carried out on an extensive scale, under con- 
trolled methods, is an expensive practice. The burning done by 
160-acre blocks was reported by the California Forestry Committee 
as costing $1 per acre. Later, when burning was done by 640-acre 
units, the company reported that the cost was reduced to 374 cents 
per acre. | 
SUMMARY OF LIGHT-BURNING OBSERVATIONS 
In order for it to satisfactorily and economically accomplish the 
specific purpose of reducing the general hazard, which is its main 
purpose, light burning should meet these three conditions: 
1. The amount of inflammable material must be considerably 
reduced. 
2. The direct money cost of burning must be kept within reason- 
able limits, particularly if frequent burning of an area is found essen- 
tial to reduce the hazard. 
3. The indirect costs or damage, both in the form of merchantable 
timber and small trees, must be held to a low percentage of the total 
destructible values at stake. 
From the foregoing experiments and studies, the following main 
conclusions may be drawn. 
DIFFICULTIES OF OPERATION 
The difficulties of actually carrying out burning under any form of 
control are very great. In the spring, weather conditions may change 
so rapidly that, within a very few days after a period when fire will 
not spread at all, the danger of destructive fires may suddenly become 
formidable. 
If burning is done in spring or fall, the only time when fires can be 
handled easily and minimum damage can be expected, it is impossible 
to burn the more moist slopes. ‘Even at these seasons a sudden 
rainstorm or a sudden hot, dry period may make it impossible either 
to burn at all or to handle fires except with high expenditures and the 
likelihood of heavy damage. 
