10 BULLETIN 1294, U. S. DEPARTMENT OF AGRICULTURE 
The latter part of Table 1 shows the manner in which this rela 
tively even loss occurs. On the Ham Station fire, for example, the 
trees burned down averaged one 42-inch 7-log yellow pine on every 
11 acres burned over; one 40-inch 7-log sugar pine to every 40 acres 
burned over; one 36-inch 5-log incense cedar to every 15 acres burned 
over; and an occasional Douglas fir and white fir tree. The loss on 
the other fires studied in detail was of the same general nature; that 
is, only an occasional large tree succumbed to the flames, and on only © 
one of these fires did this loss exceed one tree to the acre. 
Of certain conspicuous exceptions involving unusually heavy losses, 
the most outstanding in this table, both as regards actual board-foot 
loss and destruction of trees per acre, are the Moffitt Creek and the 
Pilot Creek fires. ‘These exceptional losses are traceable to the pre- 
vious fires in the stand. Jxamination on the ground made it quite - 
certain that fires have been more frequent on these two areas than 
on the other areas of virgin forest studied, or for that matter, more 
frequent than the average for the pine region of California. The 
Moffitt Creek area represents the maximum damage so far encoun- 
tered in number of trees down. The loss recorded amounts to more 
than one tree to the acre, or very nearly 10 per cent of the total mer- 
chantable stand. 
Once fire reaches the base of the trees the main factor which deter- 
mines the amount of loss from burning down is the prevalence of scars 
from previous fires. In the California pine forests, the amount of 
inflammable material, general intensity of the fire, season of burning, 
rate of spread, and similar factors are only secondarily important in 
the final outcome. 
This loss for any particular area, therefore, must be anticipated, 
whether the fire is light or heavy, and whether it burns in the spring, 
summer, or fall. Although the elimination of an occasional tree is 
ordinarily inconspicuous and a loss easily overlooked, nevertheless it 
averages 930 board feet per acre, a factor to be reckoned with. 
Furthermore, the process of attrition, which results in the burning 
down of an occasional tree, speeds up when fires on a particular area 
are frequent, for the scarred trees then have little opportunity to 
cover over the wounds with a new layer of wood, and each new fire 
capital in full the effects of previous fires. 
n any case, the resultant loss is peculiarly unfortunate because of 
the very large and high-grade trees that succumb. Stumpage apprais- 
als on the Ham Station fire, for example, show that while the average 
percentage of upper grades in the entire stand of yellow pine and 
sugar pine is 40 per cent, for the trees of these species burned down 
itis more than 60 per cent. Thus, aside from the loss of actual ma- 
terial, burning down results in a lowering of the quality of the stand. 
DIRECT LOSS OF WOOD AND REDUCTION IN GRADE 
So far fire scars in standmg, merchantable trees have been con- 
sidered only to the extent that they may ultimately result in the loss 
of the tree through burning down. In many cases, however, a single 
fire does not result in the loss of a tree but does burn out a certain 
amount of wood in the butt log, and, in the case of the two pines and 
Douglas fir, causes the wood surrounding the fire scar to become very 
pitchy. Although this direct loss of wood is not a high percentage 
