ROLE OF FIRE IN CALIFORNIA PINE FORESTS 43 
on the slopes of Mount Shasta and Mount Lassen, that complete re- 
stocking will be a matter of several tree generations, or of planting. 
The very nature of brush fields, with their dense uninterrupted 
canopy of inflammable material and their heavy accumulation of 
ground .litter, makes them strikingly susceptible to crown fires. 
Although not all brush fires develop into crown fires, a high percentage 
of them do. A crown fire in brush will destroy the young coniferous 
trees that may be present. Many investigations of fire damage in re- 
stocking brush fields have been made and all show convincingly that 
the survival of any tree growth on the area burned is the rare exception. 
Brush fires, like those in timber, are frequently patchy and do not 
cover all the area within their boundaries. On most large fires islands 
and patches escape, but they represent only a small fraction of the 
total area. 
Fires in virgin forests may destroy valuable merchantable timber, 
the capital stock, and may indeed wipeit out on asmallarea. Unless, 
however, fire is repeated a number of times, which is becoming less 
and less likely as fire protection improves, the forest suffers merely 
a reduction in density and the area remains in the productive class. 
Fires in the brush fields, on the contrary, are of serious moment, not 
because they destroy merchantable timber, but because at one stroke 
they may sweep the new forest from thousands of acres and even 
destroy the scattered seed trees that are necessary to maintain the 
forest type. 
The amount of reproduction present in the brush fields to-day is 
very much greater than would seem on superficial examination, for 
in many places the young trees are just beginning to break through 
the brush canopy and to become easily visible. This condition is 
wholly the result of 15 to 20 or 25 years of fire exclusion. Fire in 
restocking brush fields now is little less than a calamity. (Pl. X.) 
Serious as are the tremendous losses where virgin stands have been 
converted by fire into brush fields, or where fire has swept the restock- 
ing brush fields, they can not be compared with the colossal difficulties 
the brush fields present in the management and protection of the 
_ remaining forests and in the reclamation of these waste areas them- 
selves. Nor, with our present protective system, is the problem even 
approaching solution. Table 20 shows for a period of years the 
comparative size of fires in timber and in brush and the relative area 
_ of each type burned compared to the total area ofeach class. Not only 
do fires in brush attain a greater average size than in timber, but for 
_ equal areas of timber land and brush land nearly seven times as many 
_ acres of brush land are being burned each year as of timber. 
TasBLE 20.—Relative size of timber and brush fires in California, 1916 to 1918, 
inclusive 
| Timber Brush 
LEE Dy SS 08 Se i le EE he ee Ee ee acres | 10, 000, 000 5, 000, 000 
Wier is eT coe ee oe ee Pe ee Ve Fe ee AT ee ae 1, 757 1,878 
acres. .-.- 66, 690 204 7 
OSS SEE SER SS ES. 1) os i, 2 nS aaa ae { per cent... 0.7 41 
NER ERATOR TICS a =e - n= a = es -- toe e+ === acres - 114 327 
/roperiion of fires Over 10 acres in size______ ___-_.-----_.-----.------ per cent_- 18.3 _ 42.4 
renner cement eveneriee lyre SUL iat Sed ce Bolo sere $25. 75 $98. 40 
i Estimated—no absolute figures available. 
