Apr. 15,1925 Use of Liability Ratings in Forest Fire Protection 
741 
Table X .—Average value of timber and young growth destroyed per acre burned 
over 
Forest type 
Region 
Western 
yellow 
pine and 
sugar 
pine 
Douglas 
fir and 
larch 
Lodge- 
pole pine 
Spruce 
and firs 
White 
pine 
Sub- 
alpine 
Wood¬ 
land 
Brush 
Grass 
Dollars 
Dollars 
Dollars 
Dollars 
Dollars 
Dollars 
Dollars 
Dollars 
Dollars 
1_ 
5.92 
4.95 
10.40 
«0.29 
0. 29 
2_ 
4. 75 
4.45 
4.63 
14. 97 
14.20 
2. 24 
.29 
.29 
3_ 
4. 36 
8.03 
4.79 
14. 65 
14. 20 
2. 24 
.29 
.29 
4_ 
5.13 
9.44 
5. 54 
13. 97 
2.80 
.47 
.47 
5... 
6. 61 
8.12 
3.86 
6_ 
6.15 
4. 82 
2. 97 
4. 72 
1.40 
1. 22 
. 78 
.04 
7_ 
5. 27 
3.18 
3. 76 
1.40 
.33 
. 78 
.04 
8_ 
8.23 
5.12 
3.10 
S. 12 
5. 28 
.94 
.47 
9_ 
6.12 
4. 77 
2. 90 
10. 40 
®. 30 
°. 30 
10- __ 
6.31 
5.24 
4. 25 
12. 39 
°. 30 
«. 30 
11 _ 
2. 95 
.65 
. 65 
12 ... 
3. 37 
3.16 
7. 98 
6. 29 
3. 01 
.28 
13_ 
3. 20 
8. 50 
5. 97 
_ 
.28 
.28 
. 15 
14_ 
4. 20 
4. 68 
12.10 
6.10 
1. 68 
.53 
.53 
15_ 
8. 22 
8.83 
5.24 
5. 97 
5. 97 
.48 
.68 
1.18 
16--.,_, 
4. 59 
2. 68 
4.64 
1. 40 
. 82 
.99 
. 05 
17_ 
7.12 
6. 75 
1.40 
b . 09 
. 51 
. 51 
18_ 
4.74 
3. 62 
4. 71 
4. 71 
1. 68 
.34 
.40 
19_ 
4.74 
3.62 
8. 50 
4. 71 
4. 71 
1. 68 
.34 
.40 
20_ 
9.18 
3. 62 
4. 71 
4. 71 
1.68 
.34 
.40 
21_ 
«1. 85 
d l. 20 
1.20 
*1.20 
. 10 
<*. 10 
° Estimated, data unsatisfactory. 
b Hardwood bottoms. 
c Jack pine. 
d Spruce, balsam, tamarack, value estimated same as eastern white pine. 
* Hardwoods, value estimated same as eastern white pine. 
RATING THE LIABILITY 
Rating of the liability of a given 
individual unit involves two different 
processes. One is the rating of the 
general liability, or the liability due to 
general risk fires, which may be con¬ 
sidered as an average figure generally 
applicable to the entire area of a given 
type within one region. The other 
process is the rating of the special 
liability due to special risk fires, which 
can not be applied generally but will be 
different for each specific unit. In 
each of these cases the rating should 
include the total liability of each sort, 
i. e., the liability of loss, plus the sup¬ 
pression liability. 
General liability —Since the gene¬ 
ral risk has been assumed to be spread 
fairly evenly over the whole extension 
of a given type within one region, the 
general liability will be uniform for 
equal areas of the type, provided they 
are subject to the same “hour control,” 
no matter which individual forest unit 
within that region may be under 
consideration. This liability will be the 
product of the sum of probable average 
loss plus probable average suppression 
cost per fire for the given hour control, 
multiplied by the average number of 
fires per year per unit of area of the 
given type, and can be computed as 
follows: 
1. Average sizes of fires for different 
hour-control periods are shown in 
Figures 4—18. 
2. Average damage per acre burned 
over is found in Table X. The prod¬ 
ucts of these two sets of figures give 
average damage per fire. 
3. Average suppression costs per fire 
for different hour control periods are 
given in Table VI. 
4. The average numbers of general 
risk fires per 1,000 acres of each type 
and region are given in Table XI. 
5. The sums of damages and costs, 
found as outlined above, multiplied by 
number of fires, gives the general 
liability per 1,000 acres for each type 
and region according to different hour 
controls. These values are given in 
Table XII.* 
4 Tables were also prepared for regions 1, 5? 7, 9,10,11,13, 14, 15, 18, and 20, but are omitted because 
of the rather inadequate data on which they are based. 
