34, 
brings out valuable indicators for the placing of fire guards and deter- 
mining the size of suppression crews. 
One of the salient indications of the data studied has been the 
necessity for far greater development of the present protection organ- 
izations, and other protection effort. This has appeared in the figures 
estimating the percentage of type area burned annually, when com- 
‘pared with the proposed acceptable maximum of 0.2 per cent of area 
per year. (Fig.11.) In the fir type alone has fire been kept below this 
maximum. ‘The most valuable timber type, the western yellow pine, 
stands an annual loss from fires of all sorts of more than five times this 
figure, a loss that need occur 
successively for only about 90 
years to burn over the entire 
area of the type. Restocking 
brush fields, where young growth 
BULLETIN 1495, U. S. DEPARTMENT OF AGRICULTURE 
| 
U4 
4500 
LMM 
—~ 
Md 
YELLOW 
PINE 
Uj). ..MIXED| CONIFER 
3000 
WM 
_~ BRUSH 
(A, 
YllMMo 
NUMBER OF ACRES-100 THOUSANDS 
& 
ie) 
1@) 
Wl 
Y\...- WOODLAND 
------.SUGAR PINE -FIR 
750 
WLM M@ IL 
LI. 
WY 
"NG 
fo) 
BERS NUMBER OF ACRES IN TYPE 
Gd TOTAL AREA BURNED-ALL CAUSES, 1911-1920 
FIGURE 11.—Area burned in decade, in relation to 
total area of type, all causes, 1911-1920 
fairly definitely to certain means by 
if protected will develop profit- 
able timber stands of pine and 
fir, are being burned over at a 
still higher annualrate. At this 
rate only 70 years would be re- 
quired to destroy utterly this 
promise of future timber forests. 
lf this study of forest cover 
as related to fire control did no 
more than poimt out these 
dangerous shortcomings in the 
present protection organization, 
the work would probably be 
fully justified. It is true that 
the investigations discussed 
here lead to no final mathemat- 
ical expression of the differences 
between types nor of the corre- 
sponding changes needed in fire 
control. They do, however, 
yield indications that are vital 
in the perfecting of the protec- 
tion organization. They point 
unmistakably to the types in 
which protective work must be 
immediately increased if forest 
values are to be preserved, and 
which this end may be attained. 
Type has been shown to be a factor in the number of man-caused 
fires and can well be taken into account in the application of any 
restrictive measures which are designed to prevent fires from starting, 
and which are directed against campers in general or against smoking 
in the woods. Where it appears desirable to close certain forest areas 
to all forms of use, a knowledge of type differences may be of con- 
siderable assistance in defining these areas. This knowledge may 
also be of value as a guide in the extension of such measures as that 
of removing fuels from along roads, trails, and railroads, or of building 
fire lines in areas of high hazard, breaking up brush area into blocks, or 
separating low-value chaparral from brush or commercial yellow pine. 
