2 BULLETIN 1294, U. S. DEPARTMENT OF AGRICULTURE 
of the ultimate work of fire; but the connecting links between these 
conditions and the “‘harmless’’ forest fire are usually not known or 
are overlooked, so gradual is the cumulative effect. 
Fire scars and heat killing begin the destructive work and lead 
directly to burning down oi trees or susceptibility to wind throw, to 
insect infestation, to decay from fungous diseases. Each fire accel- 
erates the progress and effects of the next; each successive fire adds 
its often imperceptible weight to the force of attrition that thins the 
stand, weeds out the finest individual trees, and gradually reduces 
the forest in quality and quantity to the point where the returns will 
not justify the cost of logging. Where logging has been in progress, 
the broadcast slash fire sweeps over with perhaps little apparent 
permanent damage; but in its path reproduction, the basis of the 
new forest,is gone and will return only after many decades. The 
few seed trees left are weakened and are prey to the first strong wind. 
Brush sprouts from the unburned roots and gains the mastery. The 
next fire will blaze as fiercely as the slash burn. If any tree seed- 
lings are still striving to regain the land for timber, they will be wiped 
out completely. At the borders of the brush field, the skirmish find 
of timber and brush, the fire will attack the vanguard of the forest 
with all the strength of a crown fire, and the forest will give way 
" again before it. 
These are the links in the chain. Once they are seen and under- 
stood, fire in the California pine region can no longer be regarded as 
the friend of man or a negligible foe. Its réle of destroyer is as 
unmistakable here as elsewhere. 
The habit of thinking of the forest as an inexhaustible source of 
material, to be mined rather than grown as a crop, has been an ob- 
stacle to a general appreciation of the destructiveness of fire. 
Another obstacle has been the difficulty of obtaining the facts 
regarding damage, and the consequent ease with which the case 
could be overstated or understated. Although the importance of fire 
damage was recognized by the earliest administrative and investiga- 
tive officers of the Forest Service working in California, and although 
estimates of fire damage have been made a part of each report ever 
since systematic fire protection was begun in that State, the figures 
compiled have proved to be in general very much below the actual 
damage (23) .? | : 
How seriously misleading these figures may be is shown by a cruise 
of five large fires made after a considerable lapse of time. ‘This criti- 
cal survey disclosed a direct loss of 2,000 board feet to the acre, in 
contrast with the orginal estimates, made directly after the fire, of 
only 525 board feet to the acre. Thus with few definite facts to work 
with, much misstatement of the situation, and in some cases unreli- 
able data, it has in the past been difficult to bring out any reliable 
and convincing estimate of fire damage. 
The object of this bulletin is to present the available facts of fire 
damage. ‘This is attempted by means of a careful examination of 
the various forms of damage, both direct and secondary; by an esti- 
mate of the seriousness of each form of injury, of the immediate loss 
and also of the indirect cost; and by a survey of the effect of such 
41 Numbers in italics in parentheses refer to ‘Literature citied’’ on p. 80. 
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fatty 
